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1.  Effect of Intensive Diabetes Treatment on Carotid Artery Wall Thickness in the Epidemiology of Diabetes Interventions and Complications 
Diabetes  1999;48(2):383-390.
The Epidemiology of Diabetes Interventions and Complications (EDIC) is a multicenter longitudinal observational study of the Diabetes Control and Complications Trial (DCCT) cohort. One of the major objectives of EDIC is to study the development and progression of atherosclerotic cardiovascular disease in type 1 diabetes. In this study, we evaluated the role of cardiovascular risk factors and antecedent therapy in the DCCT on carotid intima-media wall thickness (IMT) in type 1 diabetes. At ~18 months after the end of the DCCT, high-resolution B-mode ultrasonography was used to assess the carotid arteries of 1,325 patients with type 1 diabetes, 19–51 years of age, with duration of diabetes ranging from 6.3 to 26.1 years. An age- and sex-matched nondiabetic population (n = 153) was studied with the same protocol. The ultrasound protocol was carried out in 28 EDIC clinics by centrally trained and certified sonographers using one of three scanning systems. Determination of IMT from videotaped images was performed by a single reader at the Central Ultrasound Reading Unit. Univariate associations with greater IMT were strongest for older age and longer diabetes duration, greater waist-to-hip ratio (men only), higher blood pressure, higher LDL cholesterol, and smoking. The DCCT therapy group (intensive versus conventional) and HbA1c, measured at the time of the ultrasound or the mean HbA1c during the DCCT, were not significantly related to IMT. Multivariate analyses suggest that age, height, smoking, and BMI were the major predictors of common carotid IMT, whereas age, smoking, and LDL cholesterol predicted internal carotid IMT. There were significant differences between the IMT values of the internal carotid artery in the EDIC male cohort and similarly aged male nondiabetic control subjects. There were no significant differences between the IMT values in the EDIC female cohort and similarly aged female nondiabetic control subjects. At this point in the planned 10-year follow-up of the DCCT cohort, neither intensive therapy nor HbA1c level appears to influence the early signs of atherosclerosis. Traditional risk factors, including age, smoking, and LDL cholesterol, were related to IMT. As the cohort is only now entering the age interval during which rapid progression and clinical expression of atherosclerosis are expected, further follow-up will help to determine the role of hyperglycemia, and its interaction with other risk factors, on the development of atherosclerosis.
PMCID: PMC2622732  PMID: 10334318
2.  Update on Cardiovascular Outcomes at 30 Years of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study 
Diabetes Care  2013;37(1):39-43.
OBJECTIVE
To describe the beneficial long-term effects of an average of 6.5 years of intensive diabetes therapy (INT) in type 1 diabetes on measures of atherosclerosis, cardiac structure and function, and clinical cardiovascular events observed in the Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) study.
RESEARCH DESIGN AND METHODS
The DCCT was a randomized clinical trial of 1,441 participants assigned to receive INT or conventional therapy (CON). It was conducted between 1983–1993 with an average follow-up of 6.5 years. EDIC (1994–present) is an observational follow-up of the DCCT cohort. Cardiovascular events have been recorded throughout. During EDIC common carotid intima-media thickness (IMT) was measured with ultrasound, coronary artery calcification with computed tomography, and cardiac structure and function with cardiac magnetic resonance imaging.
RESULTS
DCCT INT and lower levels of HbA1c during DCCT/EDIC were associated with thinner carotid IMT, less coronary calcification, and a lower incidence of clinical cardiovascular events including myocardial infarction, stroke, and cardiac death. While there were no significant differences in cardiac structure and function between the former INT and CON groups, they were significantly associated with higher HbA1c during DCCT/EDIC.
CONCLUSIONS
DCCT INT and the attendant 6.5 years of lower HbA1c had long-term salutary effects on the development and progression of atherosclerosis and cardiovascular disease during the subsequent follow-up during EDIC.
doi:10.2337/dc13-2116
PMCID: PMC3868002  PMID: 24356596
3.  The effect of excess weight gain with intensive diabetes treatment on cardiovascular disease risk factors and atherosclerosis in type 1 diabetes: Results from the Diabetes Control and Complications Trial / Epidemiology of Diabetes Interventions and Complications Study (DCCT/EDIC) study 
Circulation  2012;127(2):10.1161/CIRCULATIONAHA.111.077487.
Rationale
Intensive diabetes therapy of type 1 diabetes (T1DM) reduces diabetes complications but can be associated with excess weight gain, central obesity, and dyslipidemia.
Objective
The purpose of this study was to determine if excessive weight gain with diabetes therapy of T1DM is prospectively associated with atherosclerotic disease.
Methods and Results
Subjects with T1DM (97% Caucasian, 45% female, mean age 35 years) randomly assigned to intensive (INT) or conventional (CONV) diabetes treatment during the Diabetes Control and Complications Trial (DCCT) underwent intima-media thickness (IMT) (n=1015) and coronary artery calcium (CAC) score (n=925) measurements during follow-up in the Epidemiology of Diabetes Interventions and Complications (EDIC) Study. INT subjects were classified by quartile of BMI change during the DCCT. Excess gainers (4th quartile, including CONV subjects meeting this threshold) maintained greater BMI and waist circumference (WC), needed more insulin, had greater IMT (+5%, P<0.001 EDIC year 1, P=0.003 EDIC year 6), and trended towards greater CAC scores (OR 1.55, CI 0.97 – 2.49, P=0.07) than minimal gainers. DCCT subjects meeting metabolic syndrome criteria for WC and blood pressure had greater IMT in both EDIC years (P =0.02 to <0.001); those meeting HDL criteria had greater CAC scores (OR 1.6 and CI 1.1 – 2.4, P=0.01) during follow-up. Increasing frequency of a family history of diabetes, hypertension, and hyperlipidemia was associated with greater IMT thickness with INT but not CONV.
Conclusions
Excess weight gain in DCCT is associated with sustained increases in central obesity, insulin resistance, dyslipidemia and blood pressure, as well as more extensive atherosclerosis during EDIC.
doi:10.1161/CIRCULATIONAHA.111.077487
PMCID: PMC3819101  PMID: 23212717
diabetes mellitus; carotid intima media thickness; coronary artery calcium; imaging; obesity
4.  Intensive Diabetes Therapy and Carotid Intima–Media Thickness in Type 1 Diabetes Mellitus 
The New England journal of medicine  2003;348(23):2294-2303.
BACKGROUND
Cardiovascular disease causes severe morbidity and mortality in type 1 diabetes, although the specific risk factors and whether chronic hyperglycemia has a role are unknown. We examined the progression of carotid intima–media thickness, a measure of atherosclerosis, in a population with type 1 diabetes.
METHODS
As part of the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the long-term follow-up of the Diabetes Control and Complications Trial (DCCT), 1229 patients with type 1 diabetes underwent B-mode ultrasonography of the internal and common carotid arteries in 1994–1996 and again in 1998–2000. We assessed the intima–media thickness in 611 subjects who had been randomly assigned to receive conventional diabetes treatment during the DCCT and in 618 who had been assigned to receive intensive diabetes treatment.
RESULTS
At year 1 of the EDIC study, the carotid intima–media thickness was similar to that in an age- and sex-matched nondiabetic population. After six years, the intima–media thickness was significantly greater in the diabetic patients than in the controls. The mean progression of the intima–media thickness was significantly less in the group that had received intensive therapy during the DCCT than in the group that had received conventional therapy (progression of the intima–media thickness of the common carotid artery, 0.032 vs. 0.046 mm; P=0.01; and progression of the combined intima–media thickness of the common and internal carotid arteries, −0.155 vs. 0.007; P=0.02) after adjustment for other risk factors. Progression of carotid intima–media thickness was associated with age, and the EDIC base-line systolic blood pressure, smoking, the ratio of low-density lipoprotein to high-density lipoprotein cholesterol, and urinary albumin excretion rate and with the mean glycosylated hemoglobin value during the mean duration (6.5 years) of the DCCT.
CONCLUSIONS
Intensive therapy during the DCCT resulted in decreased progression of intima–media thickness six years after the end of the trial.
doi:10.1056/NEJMoa022314
PMCID: PMC2701300  PMID: 12788993
5.  Epidemiology of Diabetes Interventions and Complications (EDIC) 
Diabetes care  1999;22(1):99-111.
OBJECTIVE
The Diabetes Control and Complications Trial (DCCT) demonstrated the powerful impact of glycemic control on the early manifestations of microvascular complications. Contemporary prospective data on the evolution of macrovascular and late microvascular complications of type 1 diabetes are limited. The Epidemiology of Diabetes Interventions and Complications (EDIC) study is a multicenter, longitudinal, observational study designed to use the well-characterized DCCT cohort of >1,400 patients to determine the long-term effects of prior separation of glycemic levels on micro- and macrovascular outcomes.
RESEARCH DESIGN AND METHODS
Using a standardized annual history and physical examination, 28 EDIC clinical centers that were DCCT clinics will follow the EDIC cohort for 10 years. Annual evaluation also includes resting electrocardiogram, Doppler ultrasound measurements of ankle/arm blood pressure, and screening for nephropathy. At regular intervals, a timed 4-h urine is collected, lipid profiles are obtained, and stereoscopic fundus photographs are taken. In addition, dual B-mode Doppler ultrasound scans of the common and internal carotid arteries will be performed at years 1 and 6 and at study end.
RESULTS
Written informed consent was obtained from 96% of the DCCT subjects. The participants, compared with nonparticipants, tended to have better glycemic control at the completion of the DCCT and were more likely to have their diabetes care provided by DCCT personnel. The EDIC baseline measurement stratified by sex delineates multiple cardiovascular disease risk factor differences such as age (older in men), waist-to-hip ratio (higher in men), HDL cholesterol (lower in men), hypertension (more prevalent in men), and maximum intimal-medial thickness of common and internal carotid arteries (thicker in men). Of the original conventional treatment group, 69% have changed to continuous subcutaneous insulin infusion or multiple daily injections. Although the mean HbA1c difference between the intensive and conventional treatment groups narrowed at EDIC years 1 and 2, HbA1c remained significantly lower in the intensive group. Of all expected clinic visits, 95% were completed, and the quality of EDIC data is very similar to that observed in the DCCT.
CONCLUSIONS
Although obvious problems exist in extended follow-up studies of completed clinical trials, these are balanced by the value of continued systematic observation of the DCCT cohort. In contrast to other epidemiologic studies, EDIC will provide 1) definitive data on type 1 as distinct from type 2 diabetes; 2) reliance on prospective rather than on cross-sectional analysis; 3) long-term follow-up in a large population; 4) consistent use of objective, reliable measures of outcomes and glycemia; and 5) observation of patients from before the onset of complications.
PMCID: PMC2745938  PMID: 10333910
6.  Levels of Oxidized LDL and Advanced Glycation End Products–Modified LDL in Circulating Immune Complexes Are Strongly Associated With Increased Levels of Carotid Intima-Media Thickness and Its Progression in Type 1 Diabetes 
Diabetes  2011;60(2):582-589.
OBJECTIVE
High cholesterol levels in circulating immune complexes (IC), surrogate markers of modified LDL, are associated with increased carotid intima-media thickness (IMT) and cardiovascular events in type 1 diabetes. Different modifications of LDL are involved in IC formation, but which of these are predictive of vascular events is not known. Therefore, we measured oxidized LDL (oxLDL), advanced glycation end products–modified LDL (AGE-LDL), and malondialdehyde-modified LDL (MDA-LDL) in IC and determined their relationship with increased carotid IMT and compared the strength of the association with that observed with conventional risk factors.
RESEARCH DESIGN AND METHODS
Levels of oxLDL, AGE-LDL, and MDA-LDL were measured in circulating IC isolated from sera of 479 patients of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort, collected at baseline. Internal and common carotid IMT were measured 8 and 14 years later by DCCT/EDIC.
RESULTS
OxLDL, AGE-LDL, and MDA-LDL levels in circulating IC were significantly correlated with diabetes duration, BMI, and lipid and blood pressure, but not with age. Multivariate logistic regression models indicated that individuals in the highest versus lowest quartile of oxLDL and AGE-LDL in IC had a 6.11-fold [confidence interval (CI) 2.51–14.8] and a 6.4-fold (CI 2.53–16.2) increase in the odds of having high carotid IMT, respectively, after adjusting for conventional risk factors. Parallel analyses resulted in odds ratios of 2.62 (CI 1.24, 5.55) for LDL-C, 1.45 (CI 0.69, 3.03) for diastolic blood pressure, and 2.33 (CI 1.09, 4.99) for A1C.
CONCLUSIONS
OxLDL and AGE-LDL in circulating IC were significantly associated with progression and increased levels of carotid IMT in type 1 diabetes.
doi:10.2337/db10-0915
PMCID: PMC3028359  PMID: 20980456
7.  Risk Factors Related to Inflammation and Endothelial Dysfunction in the DCCT/EDIC Cohort and Their Relationship With Nephropathy and Macrovascular Complications  
Diabetes Care  2008;31(10):2006-2012.
OBJECTIVE—Because endothelial cell dysfunction and inflammation are key contributors to the development of complications in type 1 diabetes, we studied risk factors related to endothelial dysfunction and inflammation (C-reactive protein and fibrinogen, soluble vascular cell adhesion molecule-1, intracellular adhesion molecule-1, and E-selectin, and fibrinolytic markers) in a subgroup of patients from the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Intervention and Complications (EDIC) study cohort.
RESEARCH DESIGN AND METHODS—We determined which of these risk factors or clusters thereof are associated with the presence of and subsequent development of nephropathy and macrovascular complications (reflected by carotid intima-media thickness [IMT]).
RESULTS—After adjustment for conventional risk factors (age, sex, DCCT treatment group, diabetes duration, A1C, systolic blood pressure, waist-to-hip ratio, total and HDL cholesterol, and smoking status), fibrinogen remained strongly associated with progression of internal and common carotid IMT (P < 0.01) and soluble E-selectin had a strong association with nephropathy (P < 0.01).
CONCLUSIONS—The best predictor for IMT progression in the DCCT/EDIC cohort was plasma fibrinogen, and the levels of soluble E-selectin discriminate patients with albuminuria better than conventional risk factors.
doi:10.2337/dc08-0659
PMCID: PMC2551645  PMID: 18628568
8.  Sustained Effect of Intensive Treatment of Type 1 Diabetes Mellitus on Development and Progression of Diabetic Nephropathy 
Context
The Diabetes Control and Complications Trial (DCCT) demonstrated the benefits of intensive treatment of diabetes in reducing glycemic levels and slowing the progression of diabetic nephropathy. The DCCT cohort has been examined annually for another 8 years as part of the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study, During the EDIC study, glycemic levels no longer differed substantially between the 2 original treatment groups.
Objective
To determine the long-term effects of intensive vs conventional diabetes treatment during the DCCT on kidney function during the EDIC study.
Design, Setting, and Participants
Observational study begun in 1993 (following DCCT closeout) in 28 medical centers in the United States and Canada. Participants were 1349 (of 1375) EDIC volunteers who had kidney evaluation at years 7 or 8.
Main Outcome Measures
Development of microalbuminuria, clinical-grade albuminuria, hypertension, or increase in serum creatinine level.
Results
Results were analyzed by intention-to-treat analyses, comparing the 2 original DCCT treatment groups. New cases of microalbuminuria occurred during the EDIC study in 39 (6.8%) of the participants originally assigned to the intensive-treatment group vs 87 (15.8%) of those assigned to the conventional-treatment group, for a 59% (95% confidence interval [CI], 39% -73%) reduction in odds, adjusted for baseline values, compared with a 59% (95% CI, 36%-74%) reduction at the end of the DCCT (P<.001 for both comparisons). New cases of clinical albuminuria occurred in 9 (1.4%) of the participants in the original intensive-treatment group vs 59 (9.4%) of those in the original conventional-treatment group, representing an 84% reduction in odds (95% Cl, 67%-92%), compared with a reduction of 57% (95% CI, -1 % to +81%) at the end of the DCCT. Fewer cases of hypertension (prevalence at year 8, 29.9% vs 40.3%; P<.001) developed in the original intensive-treatment group. Significantly fewer participants reached a serum creatinine level of 2 mg/dL or greater in the intensive-treatment vs the conventional-treatment group (5 vs 19, P=.004), but there were no differences in mean log clearance values. Although small numbers of patients required dialysis and/or transplantation, fewer patients experienced either of these outcomes in the intensive group (4 vs 7, P=.36).
Conclusions
The persistent beneficial effects on albumin excretion and the reduced incidence of hypertension 7 to 8 years after the end of the DCCT suggest that previous intensive treatment of diabetes with near-normal glycemia during the DCCT has an extended benefit in delaying progression of diabetic nephropathy.
doi:10.1001/jama.290.16.2159
PMCID: PMC2622725  PMID: 14570951
9.  Oxidized LDL and AGE-LDL in Circulating Immune Complexes Strongly Predict Progression of Carotid Artery IMT in Type 1 Diabetes 
Atherosclerosis  2013;231(2):315-322.
Objective
Over 90% of modified LDL in circulation is associated to specific antibodies circulating as part of immune complexes (IC); however, few studies have examined their relationship with cardiovascular disease.
Methods
We report the relationship between circulating concentrations of IC of oxidized LDL (oxLDL-IC), malondialdehyde-LDL (MDA-LDL-IC) and advanced glycation end products-LDL (AGE-LDL-IC) and progression of atherosclerosis over a 12 year period in 467 individuals with type 1 diabetes who participated in the Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) study. OxLDL-IC, AGE-LDL-IC and MDA-LDL-IC levels were measured at DCCT closeout. Internal carotid intima-medial thickness (IMT) was measured at EDIC follow-up years 1, 6 and 12.
Results
OxLDL-IC, AGE-LDL-IC and MDA-LDL-IC levels were significantly correlated with age, lipid levels, blood pressure levels and albumin excretion rates. Levels of oxLDL, AGE-LDL and MDA-LDL in isolated LDL-IC were highly inter-correlated (r=0.66 to 0.84, p<0.0001). After adjusting for cardiovascular risk factors individuals in the upper quartile of oxLDL-IC had a 2.98fold increased odds (CI: 1.34, 6.62) of having IMT ≥ 1.00 mm and had a 5.13-fold increased odds (CI: 1.98, 13.3) of having significant IMT progression, relative to those in the lowest quartile. Parallel odds ratios for AGE-LDL-IC were 2.95 (CI: 1.37, 6.34) and 3.50 (CI: 1.38, 8.86), while results for MDA-LDL-IC were 1.76 (0.87, 3.56) and 2.86 (1.20, 6.81).
Conclusion
Our study indicates that high levels of oxLDL-IC and AGE-LDL-IC are important predictors of carotid intima-medial thickening in patients with type 1 diabetes.
doi:10.1016/j.atherosclerosis.2013.09.027
PMCID: PMC3924569  PMID: 24267245
modified LDL; subclinical atherosclerosis; carotid artery intima-media thickness; type 1 diabetes
10.  Effects of Prior Intensive Versus Conventional Therapy and History of Glycemia on Cardiac Function in Type 1 Diabetes in the DCCT/EDIC 
Diabetes  2013;62(10):3561-3569.
Intensive diabetes therapy reduces the prevalence of coronary calcification and progression of atherosclerosis and the risk of cardiovascular disease (CVD) events in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study. The effects of intensive therapy on measures of cardiac function and structure and their association with glycemia have not been explored in type 1 diabetes (T1DM). We assess whether intensive treatment compared with conventional treatment during the DCCT led to differences in these parameters during EDIC. After 6.5 years of intensive versus conventional therapy in the DCCT, and 15 years of additional follow-up in EDIC, left ventricular (LV) indices were measured by cardiac magnetic resonance (CMR) imaging in 1,017 of the 1,371 members of the DCCT cohort. There were no differences between the DCCT intensive versus conventional treatment in end diastolic volume (EDV), end systolic volume, stroke volume (SV), cardiac output (CO), LV mass, ejection fraction, LV mass/EDV, or aortic distensibility (AD). Mean DCCT/EDIC HbA1c over time was associated with EDV, SV, CO, LV mass, LV mass/EDV, and AD. These associations persisted after adjustment for CVD risk factors. Cardiac function and remodeling in T1DM assessed by CMR in the EDIC cohort was associated with prior glycemic exposure, but there was no effect of intensive versus conventional treatment during the DCCT on cardiac parameters.
doi:10.2337/db12-0546
PMCID: PMC3781466  PMID: 23520132
11.  Effects of Prior Intensive Insulin Therapy on Cardiac Autonomic Nervous System Function in Type 1 Diabetes: The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study (DCCT/EDIC) 
Circulation  2009;119(22):2886-2893.
Background
The Epidemiology of Diabetes Interventions and Complications (EDIC) study, a prospective observational follow-up of the Diabetes Control and Complications Trial (DCCT) cohort, reported persistent benefit of prior intensive therapy on retinopathy and nephropathy in type 1 diabetes. We evaluated the effects of prior intensive insulin therapy on the prevalence and incidence of cardiac autonomic neuropathy (CAN) in former DCCT intensive (INT) and conventional (CONV) therapy subjects13-to-14 (13/14) years after DCCT closeout.
Methods and Results
DCCT autonomic measures (R-R variation with paced breathing, Valsalva ratio, postural blood pressure changes, and autonomic symptoms) were repeated in 1,226 EDIC subjects in EDIC year 13/14. Logistic regression models were used to calculate the odds of incident CAN by DCCT treatment group after adjusting for DCCT baseline covariates, duration in the DCCT, and quantitative autonomic measures at DCCT closeout. In EDIC year 13/14, the prevalence of CAN using the DCCT composite definition was significantly lower in former INT group vs. former CONV group (28.9 vs. 35.2%; P = 0.018). Adjusted R-R variation was significantly greater in former DCCT INT vs. former CONV group (29.9 vs.25.9, P < 0.001). Prior DCCT intensive therapy reduced the risks of incident CAN by 31% [odds ratio(95% CI) 0.69 (0.51–0.93)] and of incident abnormal R-R variation by 30% [odds ratio(95%CI) 0.70 (0.51–0.96)] in EDIC year 13/14.
Conclusions
Although CAN prevalence increased in both groups, the incidence was significantly lower in former INT group compared to former CONV group. The benefits of former intensive therapy extend to measures of CAN up to 14 years after DCCT closeout.
doi:10.1161/CIRCULATIONAHA.108.837369
PMCID: PMC2757005  PMID: 19470886
type 1 diabetes mellitus; cardiac autonomic neuropathy; nervous system autonomic; intensive glucose control; metabolic memory
12.  Neuropathy and Related Findings in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study 
Diabetes Care  2013;37(1):31-38.
OBJECTIVE
To describe the development and progression of neuropathy and related findings among patients with type 1 diabetes who participated in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study.
RESEARCH DESIGN AND METHODS
The main diabetic peripheral neuropathy (DPN) outcome was assessed using clinical symptoms, signs, and nerve conduction study results during DCCT and repeated in EDIC year 13/14. Cardiovascular autonomic neuropathy (CAN) was assessed by R-R response to paced breathing, Valsalva ratio, and blood pressure response to standing during DCCT and in EDIC years 13/14 and 16/17. Additionally, symptoms reflecting neuropathic pain and autonomic function (including hypoglycemia awareness) were collected yearly in EDIC using standardized questionnaires; peripheral neuropathy was also assessed annually using the Michigan Neuropathy Screening Instrument. Assessments of genitourinary function were collected at EDIC year 10.
RESULTS
Intensive therapy during the DCCT significantly reduced the risk of DPN and CAN at DCCT closeout (64% and 45%, respectively, P < 0.01). The prevalence and incidence of DPN and CAN remained significantly lower in the DCCT intensive therapy group compared with the DCCT conventional therapy group through EDIC year 13/14.
CONCLUSIONS
The persistent effects of prior intensive therapy on neuropathy measures through 14 years of EDIC largely mirror those observed for other diabetes complications. DCCT/EDIC provides important information on the influence of glycemic control, and the clinical course of diabetic neuropathy, and, most important, on how to prevent neuropathy in type 1 diabetes.
doi:10.2337/dc13-2114
PMCID: PMC3868000  PMID: 24356595
13.  Relationship between Carotid Intima-Media Thickness and Left Ventricular Mass in Type 1 Diabetes: results from the Epidemiology of Diabetes Interventions and Complications (EDIC) Study 
The American journal of cardiology  2012;110(10):1534-1540.
Introduction
Type 1 diabetes mellitus is associated with early atherosclerosis and enhanced cardiovascular mortality. The relationship between carotid IMT (cIMT), a marker of subclinical atherosclerosis and left ventricular (LV) mass, an independent predictor of cardiovascular morbidity has not been previously studied in type 1 diabetics.
Methods
The Epidemiology of Diabetes Interventions and Complications (EDIC) study is a multicenter observational study designed to follow up the Diabetes Control and Complications Trial (DCCT) cohort. LV mass was measured with cardiac MRI at EDIC year 15 and common cIMT was assessed using B-mode ultrasound at EDIC year 12. Multivariable linear regression models were used to assess the relationship between cIMT at year 12 and LV mass at year 15.
Results
A total of 889 participants had both cardiac MRI and cIMT measures available for these analyses. At EDIC year 15, the mean age of the participants was 49 (±7) years; mean diabetes duration was 28 (±5) years and 52% were males. Spearman correlation coefficient (r) between LV mass and cIMT was 0.33 (p<0.0001). After adjusting for basic covariates (machine, reader, age and gender), a significant association between LV mass and cIMT (estimate 2.0 g/m2 per 0.1 mm cIMT increment, p < 0.0001) was observed. This association was diminished by the addition of systolic blood pressure in particular 1.15 g/m2 per 0.1 mm cIMT increment, p<0.0001) and to a lessor extent other cardiovascular disease (CVD) risk factors. The relationship observed between LV mass and cIMT was stronger (HOW MUCH) in patients with shorter diabetes duration.
Conclusion
In a well characterized population with type 1 diabetes, cIMT was an independent predictor of higher LV mass. These findings suggest a common pathway, possibly mediated by blood pressure dependent mechanisms, for vascular and myocardial structural change in T1DM.
doi:10.1016/j.amjcard.2012.07.014
PMCID: PMC3488435  PMID: 22884107
14.  The Effect of Intensive Glycemic Treatment on Coronary Artery Calcification in Type 1 Diabetic Participants of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study 
Diabetes  2006;55(12):3556-3565.
The Epidemiology of Diabetes Interventions and Complications (EDIC) study, an observational follow-up of the Diabetes Control and Complications Trial (DCCT) type 1 diabetes cohort, measured coronary artery calcification (CAC), an index of atherosclerosis, with computed tomography (CT) in 1,205 EDIC patients at ~7–9 years after the end of the DCCT. We examined the influence of the 6.5 years of prior conventional versus intensive diabetes treatment during the DCCT, as well as the effects of cardiovascular disease risk factors, on CAC. The prevalences of CAC >0 and >200 Agatston units were 31.0 and 8.5%, respectively. Compared with the conventional treatment group, the intensive group had significantly lower geometric mean CAC scores and a lower prevalence of CAC >0 in the primary retinopathy prevention cohort, but not in the secondary intervention cohort, and a lower prevalence of CAC >200 in the combined cohorts. Waist-to-hip ratio, smoking, hypertension, and hypercholesterolemia, before or at the time of CT, were significantly associated with CAC in univariate and multivariate analyses. CAC was associated with mean HbA1c (A1C) levels before enrollment, during the DCCT, and during the EDIC study. Prior intensive diabetes treatment during the DCCT was associated with less atherosclerosis, largely because of reduced levels of A1C during the DCCT.
doi:10.2337/db06-0653
PMCID: PMC2701297  PMID: 17130504
15.  Prolonged Effect of Intensive Therapy on the Risk of Retinopathy Complications in Patients With Type 1 Diabetes Mellitus 
Archives of ophthalmology  2008;126(12):1707-1715.
Objective
To examine the persistence of the original treatment effects 10 years after the Diabetes Control and Complications Trial (DCCT) in the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study. In the DCCT, intensive therapy aimed at near-normal glycemia reduced the risk of microvascular complications of type 1 diabetes mellitus compared with conventional therapy.
Methods
Retinopathy was evaluated by fundus photography in 1211 subjects at EDIC year 10. Further 3-step progression on the Early Treatment Diabetic Retinopathy Study scale from DCCT closeout was the primary outcome.
Results
After 10 years of EDIC follow-up, there was no significant difference in mean glycated hemoglobin levels (8.07% vs 7.98%) between the original treatment groups. Nevertheless, compared with the former conventional treatment group, the former intensive group had significantly lower incidences from DCCT close of further retinopathy progression and proliferative retinopathy or worse (hazard reductions, 53%-56%; P<.001). The risk (hazard) reductions at 10 years of EDIC were attenuated compared with the 70% to 71% over the first 4 years of EDIC (P<.001). The persistent beneficial effects of former intensive therapy were largely explained by the difference in glycated hemoglobin levels during DCCT.
Conclusion
The persistent difference in diabetic retinopathy between former intensive and conventional therapy (“metabolic memory”) continues for at least 10 years but may be waning.
doi:10.1001/archopht.126.12.1707
PMCID: PMC2663518  PMID: 19064853
16.  Kidney Disease and Related Findings in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study 
Diabetes Care  2013;37(1):24-30.
OBJECTIVE
Kidney disease manifests clinically as elevated albumin excretion rate (AER), impaired glomerular filtration rate (GFR), or both, and is a cause of substantial morbidity and mortality in type 1 diabetes (T1D). The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study tested whether intensive diabetes therapy (INT) aimed at lowering glucose concentrations as close as safely possible to the normal range reduces the risks of kidney disease and other diabetes complications.
RESEARCH DESIGN AND METHODS
In the DCCT, 1,441 participants with T1D were randomly assigned to INT or conventional diabetes therapy (CON) for a mean duration of 6.5 years. Subsequently, participants have been followed for 18 years in the ongoing observational EDIC. Standardized longitudinal measurements of AER, estimated GFR, and blood pressure were made throughout the DCCT/EDIC.
RESULTS
During the DCCT, INT reduced the risks of incident microalbuminuria (AER ≥40 mg/24 h) and macroalbuminuria (AER ≥300 mg/24 h) by 39% (95% CI 21–52%) and 54% (29–74%), respectively. During EDIC years 1–8, participants previously assigned to DCCT INT continued to experience lower rates of incident microalbuminuria and macroalbuminuria, with risk reductions of 59% (39–73%) and 84% (67–92%), respectively. Beneficial effects of INT on the development of impaired GFR (sustained estimated GFR <60 mL/min/1.73 m2) and hypertension became evident during combined DCCT/EDIC follow-up, with risk reductions of 50% (18–69%) and 20% (6–21%), respectively, compared with CON.
CONCLUSIONS
In the DCCT/EDIC, INT resulted in clinically important, durable reductions in the risks of microalbuminuria, macroalbuminuria, impaired GFR, and hypertension.
doi:10.2337/dc13-2113
PMCID: PMC3867994  PMID: 24356594
17.  The Long-Term Effects of Type 1 Diabetes Treatment and Complications on Health-Related Quality of Life 
Diabetes Care  2013;36(10):3131-3138.
OBJECTIVE
To examine the long-term effects of type 1 diabetes treatment, metabolic control, and complications on health-related quality of life (HRQOL).
RESEARCH DESIGN AND METHODS
A total of 1,441 participants, initially 13–39 years of age, were followed for an average of 23.5 years as part of the Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) follow-up study. The Diabetes Quality-of-Life questionnaire (DQOL) was administered annually during DCCT and every other year during EDIC. Biomedical data, including HbA1c levels, exposure to severe hypoglycemia, intercurrent psychiatric events, and development of diabetes complications were collected at regular intervals throughout the follow-up.
RESULTS
Mean total DQOL scores were not significantly different between the former DCCT intensive and conventional treatment groups (DCCT baseline, 78 ± 8 vs. 78 ± 9; EDIC year 17, 75 ± 11 vs. 74 ± 11). Over the course of the study, a drop of ≥5 points in DQOL score from DCCT baseline maintained on two successive visits occurred in 755 individuals and was associated with increased HbA1c, albumin excretion rate, mean blood pressure, BMI, and occurrence of hypoglycemic events requiring assistance. Lower DQOL scores after 23.5 years of follow-up were associated with prior development of retinopathy (P = 0.0196), nephropathy (P = 0.0019), and neuropathy (P < 0.0001) as well as self-reported chest pain (P = 0.0004), decreased vision in both eyes (P = 0.0005), painful paresthesias (P < 0.0001), recurrent urinary incontinence (P = 0.0001), erectile dysfunction (P < 0.0001), and history of psychiatric events (P < 0.0001).
CONCLUSIONS
Among DCCT/EDIC participants, worsening metabolic control, serious diabetes complications and their associated symptoms, and development of psychiatric conditions led to decreased HRQOL.
doi:10.2337/dc12-2109
PMCID: PMC3781542  PMID: 23835693
18.  Effect of Intensive Therapy on the Microvascular Complications of Type 1 Diabetes Mellitus 
The purpose of this report is to summarize and integrate the findings of the Diabetes Control and Complications Trial (DCCT), a randomized controlled clinical trial, and the succeeding observational follow-up of the DCCT cohort in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, regarding the effects of intensive treatment on the microvascular complications of type 1 diabetes mellitus. The DCCT proved that intensive treatment reduced the risks of retinopathy, nephropathy, and neuropathy by 35% to 90% compared with conventional treatment. The absolute risks of retinopathy and nephropathy were proportional to the mean glycosylated hemoglobin (HbA1c) level over the follow-up period preceding each event Intensive treatment was most effective when begun early, before complications were detectable. These risk reductions, achieved at a median HbA1c level difference of 9.1 % for conventional treatment vs 7.3% for intensive treatment have been maintained through 7 years of EDIC, even though the difference in mean HbA1c levels of the 2 former randomized treatment groups was only 0.4% at 1 year (P<.001) (8.3% in the former conventional treatment group vs 7.9% in the former intensive treatment group), continued to narrow, and became statistically nonsignificant by 5 years (8.1 % vs 8.2%, P=.09). The further rate of progression of complications from their levels at the end of the DCCT remains less in the former intensive treatment group. Thus, the benefits of 6.5 years of intensive treatment extend well beyond the period of its most intensive implementation. Intensive treatment should be started as soon as is safely possible after the onset of type 1 diabetes mellitus and maintained thereafter, aiming for a practicable target HbA1c level of 7.0% or less.
PMCID: PMC2622728  PMID: 12020338
19.  Effect of Intensive Glycemic Control and Diabetes Complications on Lower Urinary Tract Symptoms in Men With Type 1 Diabetes 
Diabetes Care  2009;32(4):664-670.
OBJECTIVE
Although diabetes is known to result in lower urinary tract symptoms (LUTS) in men, it remains unclear if glycemic control can mitigate urinary symptoms. We studied how diabetic characteristics are related to LUTS in the men who completed the urological assessment component (UroEDIC) of the Epidemiology of Diabetes Interventions and Complications (EDIC) follow-up study of the Diabetes Control and Complications Trial (DCCT) participants.
RESEARCH DESIGN AND METHODS
Study participants were men who completed the UroEDIC questionnaire at the year 10 DCCT/EDIC follow-up examination, which included data on genitourinary tract function and the American Urological Association Symptom Index (AUASI). Analyses were conducted to assess how treatment arm and diabetes characteristics were associated with LUTS using logistic regression.
RESULTS
Of the 591 men who completed the AUASI questions, nearly 20% (n = 115) had AUASI scores in the moderate to severe category for LUTS (AUASI score ≥8). No associations were observed between LUTS and treatment arm, or A1C levels at the DCCT baseline or end-of-study or at the year 10 EDIC (UroEDIC) examination. Of the diabetes complications studied, only erectile dysfunction at the UroEDIC examination was associated with LUTS.
CONCLUSIONS
These data from the UroEDIC cohort do not support the assumption that intensive glycemic control results in decreased lower urinary tract symptom severity in men with type 1 diabetes. This result may be due to a true lack of effect, or it may be due to other factors, for example, the relatively young age of the cohort.
doi:10.2337/dc07-2375
PMCID: PMC2660483  PMID: 19171725
20.  Circulating Vitamin D Metabolites and Subclinical Atherosclerosis in Type 1 Diabetes 
Diabetes Care  2013;36(8):2423-2429.
OBJECTIVE
People with type 1 diabetes are at high risk of premature atherosclerosis. Existing evidence suggests that impaired vitamin D metabolism may contribute to the development of atherosclerosis. We tested associations of circulating vitamin D metabolite concentrations with subclinical atherosclerosis among 1,193 participants with type 1 diabetes in the DCCT/EDIC study.
RESEARCH DESIGN AND METHODS
We measured plasma concentrations of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D by mass spectrometry at the end of the DCCT. In a staggered cross-sectional design, we tested associations with coronary artery calcium (CAC), measured by computed tomography a median of 10 years later, and with common and internal carotid intima-media thickness (IMT), measured by B-mode ultrasonography on two occasions a median of 4 years later and a median of 10 years later. We hypothesized that lower concentrations of each vitamin D metabolite would be associated with increased risk of CAC and greater carotid IMT.
RESULTS
At the time metabolites were measured, mean age was 32.4 years and mean duration of diabetes was 7.5 years. The prevalence and severity of CAC tended to be lower—not higher—with lower concentrations of each vitamin D metabolite. For instance, in a fully adjusted multinomial logistic model, a 25 nmol/L lower 25-hydroxyvitamin D was associated with a 0.8-fold decrease in the odds of having higher CAC (95% CI 0.68–0.96, P = 0.01). No vitamin D metabolite was associated with either common or internal mean IMT.
CONCLUSIONS
We did not find evidence linking impaired vitamin D metabolism with increased subclinical atherosclerosis in type 1 diabetes.
doi:10.2337/dc12-2020
PMCID: PMC3714470  PMID: 23530012
21.  The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study at 30 Years: Summary and Future Directions 
Diabetes Care  2013;37(1):44-49.
OBJECTIVE
The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study continues to address knowledge gaps in our understanding of type 1 diabetes and the effects of intensive therapy on its long-term complications.
RESEARCH DESIGN AND METHODS
During the DCCT (1982–1993), a controlled clinical trial of 1,441 subjects with type 1 diabetes, and the EDIC (1994–present), an observational study of the DCCT cohort, core data collection has included medical history questionnaires, surveillance health exams, and frequent laboratory and other evaluations for microvascular and macrovascular disease. Numerous collaborations have expanded the outcome data with more detailed investigations of cardiovascular disease, cognitive function, neuropathy, genetics, and potential biological pathways involved in the development of complications.
RESULTS
The longitudinal follow-up of the DCCT/EDIC cohort provides the opportunity to continue monitoring the durability of intensive treatment as well as to address lingering questions in type 1 diabetes research. Future planned analyses will address the onset and progression of microvascular triopathy, evidence-based screening for retinopathy and nephropathy, effects of glycemic variability and nonglycemic risk factors on outcomes, long-term impact of intensive therapy on cognitive decline, and health economics. Three new proposed investigations include an examination of residual C-peptide secretion and its impact, prevalence of hearing impairment, and evaluation of gastrointestinal dysfunction.
CONCLUSIONS
With the comprehensive data collection and the remarkable participant retention over 30 years, the DCCT/EDIC continues as an irreplaceable resource for understanding type 1 diabetes and its long-term complications.
doi:10.2337/dc13-2148
PMCID: PMC3867991  PMID: 24356597
22.  Effect of Prior Intensive Therapy in Type 1 Diabetes on 10-Year Progression of Retinopathy in the DCCT/EDIC: Comparison of Adults and Adolescents 
Diabetes  2010;59(5):1244-1253.
OBJECTIVE
The aim of this study was to examine differences between adolescents and adults in persistence of the benefits of intensive therapy 10 years after completion of the Diabetes Control and Complications Trial (DCCT).
RESEARCH DESIGN AND METHODS
During the Epidemiology of Diabetes Interventions and Complications (EDIC) study, progression of retinopathy from DCCT closeout to EDIC year 10 was evaluated in 1,055 adults and 156 adolescents.
RESULTS
During 10 years of follow-up, HbA1c (A1C) was similar between original intensive (INT) and conventional (CON) groups and between former adolescents and adults. At EDIC year 10, adults in the former INT group continued to show slower progression of diabetic retinopathy than those in the CON group (adjusted hazard reduction 56%, P < 0.0001), whereas in adolescents this beneficial effect had disappeared (32%, P = 0.13). Seventy-nine percent of observed differences in the prolonged treatment effect between adults and adolescents at year 10 were explained by differences in mean A1C during DCCT between adolescents and adults (8.9 vs. 8.1%), particularly between INT adolescents and adults (8.1 vs. 7.2%).
CONCLUSIONS
Prior glycemic control during DCCT is vital for the persistence of the beneficial effects of INT therapy 10 years later. Lowering A1C to as close to normal as safely possible without severe hypoglycemia and starting as early as possible should be attempted for all subjects with type 1 diabetes. These results underscore the importance of maintaining A1C at target values for as long as possible because the benefits of former INT treatment wane over time if A1C levels rise.
doi:10.2337/db09-1216
PMCID: PMC2857905  PMID: 20150283
23.  The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study at 30 Years: Overview 
Diabetes Care  2013;37(1):9-16.
OBJECTIVE
The Diabetes Control and Complications Trial (DCCT) was designed to test the glucose hypothesis and determine whether the complications of type 1 diabetes (T1DM) could be prevented or delayed. The Epidemiology of Diabetes Interventions and Complications (EDIC) observational follow-up determined the durability of the DCCT effects on the more-advanced stages of diabetes complications including cardiovascular disease (CVD).
RESEARCH DESIGN AND METHODS
The DCCT (1982–1993) was a controlled clinical trial in 1,441 subjects with T1DM comparing intensive therapy (INT), aimed at achieving levels of glycemia as close to the nondiabetic range as safely possible, with conventional therapy (CON), which aimed to maintain safe asymptomatic glucose control. INT utilized three or more daily insulin injections or insulin pump therapy guided by self-monitored glucose. EDIC (1994–present) is an observational study of the DCCT cohort.
RESULTS
The DCCT followed >99% of the cohort for a mean of 6.5 years and demonstrated a 35–76% reduction in the early stages of microvascular disease with INT, with a median HbA1c of 7%, compared with CONV, with a median HbA1c of 9%. The major adverse effect of INT was a threefold increased risk of hypoglycemia, which was not associated with a decline in cognitive function or quality of life. EDIC showed a durable effect of initial assigned therapies despite a loss of the glycemic separation (metabolic memory) and demonstrated that the reduction in early-stage complications during the DCCT translated into substantial reductions in severe complications and CVD.
CONCLUSIONS
DCCT/EDIC has demonstrated the effectiveness of INT in reducing the long-term complications of T1DM and improving the prospects for a healthy life span.
doi:10.2337/dc13-2112
PMCID: PMC3867999  PMID: 24356592
24.  Neuropathy Among the Diabetes Control and Complications Trial Cohort 8 Years After Trial Completion 
Diabetes care  2006;29(2):340-344.
OBJECTIVE
To evaluate the impact of prior intensive diabetes therapy on neuropathy among former Diabetes Control and Complications Trial (DCCT) participants.
RESEARCH DESIGN AND METHODS
At the conclusion of the DCCT, subjects in the intensive group were encouraged to maintain intensive therapy, and subjects in the conventional group were encouraged to begin intensive therapy. Thereafter, we annually assessed neuropathy as part of the Epidemiology of Diabetes Intervention and Complications (EDIC) study. Neuropathy was defined using the Michigan Neuropathy Screening Instrument (MNSI). We recorded potential adverse consequences of neuropathy.
RESULTS
At the first EDIC examination, 1,257 subjects participated in the neuropathy assessment. Consistent with DCCT results, the former intensive group showed a lower prevalence of neuropathy than the conventional group based on positive questionnaire (1.8 vs. 4.7%; P = 0.003) or examination (17.8 vs. 28.0%; P < 0.0001) results. Despite similar levels of glycemic control, symptoms and signs of neuropathy remained less prevalent among the former intensive group compared with the conventional group. At the beginning of the EDIC study, prior intensive therapy reduced the odds of having symptoms and signs of neuropathy using MNSI criteria by 64% (P = 0.0044) and 45% (P < 0.0001), respectively, with similar odds reductions observed for both neuropathic symptoms (51%, P < 0.0001) and neuropathic signs (43%, P < 0.0001) across 8 years of EDIC follow-up.
CONCLUSIONS
The benefits of 6.5 years of intensive therapy on neuropathy status extended for at least 8 years beyond the end of the DCCT, similar to the findings described for diabetic retinopathy and nephropathy.
PMCID: PMC2622720  PMID: 16443884
25.  Association between seven years of intensive treatment of type 1 diabetes and long term mortality 
JAMA  2015;313(1):45-53.
Importance
Whether mortality in type 1 diabetes mellitus is affected following intensive glycemic therapy has not been established.
Objective
To determine whether mortality differed between the original intensive and conventional treatment groups in the long-term follow-up of the Diabetes Control and Complications Trial (DCCT) cohort.
Design, Setting, and Participants
After the DCCT (1983–1993) ended, participants were followed up in a multisite (27 US and Canadian academic clinical centers) observational study (Epidemiology of Diabetes Control and Complications [EDIC]) until December 31, 2012. Participants were 1441 healthy volunteers with diabetes mellitus who, at baseline, were 13 to 39 years of age with 1 to 15 years of diabetes duration and no or early microvascular complications, and without hypertension, preexisting cardiovascular disease, or other potentially life-threatening disease.
Intervention/Exposure
During the clinical trial, participants were randomly assigned to receive intensive therapy (n = 711) aimed at achieving glycemia as close to the nondiabetic range as safely possible, or conventional therapy (n = 730) with the goal of avoiding symptomatic hypoglycemia and hyperglycemia. At the end of the DCCT, after a mean of 6.5 years, intensive therapy was taught and recommended to all participants and diabetes care was returned to personal physicians.
Main Outcomes
Total and cause-specific mortality was assessed through annual contact with family and friends and through records over 27 years mean follow-up.
Results
Vital status was ascertained for 1429 (99.2%) participants. There were 107 deaths, 64 in the conventional and 43 in the intensive group. The absolute risk difference was −109 per 100 000 patient-years (95%CI, −218 to −1), with lower all-cause mortality risk in the intensive therapy group (hazard ratio [HR] = 0.67 [95%CI, 0.46–0.99]; P = .045). Primary causes of death were cardiovascular disease (24 deaths; 22.4%), cancer (21 deaths; 19.6%), acute diabetes complications (19 deaths; 17.8%), and accidents or suicide (18 deaths; 16.8%). Higher levels of glycated hemoglobin (HbA1c) were associated with all-cause mortality (HR = 1.56 [95%CI, 1.35–1.81 per 10% relative increase in HbA1c]; P < .001), as well as the development of albuminuria (HR = 2.20 [95%CI, 1.46–3.31]; P < .001).
Conclusions and Relevance
After a mean of 27 years’ follow-up of patients with type 1 diabetes, 6.5 years of initial intensive diabetes therapy was associated with a modestly lower all-cause mortality compared with conventional therapy.
doi:10.1001/jama.2014.16107
PMCID: PMC4306335  PMID: 25562265

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