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1.  Characteristics of Insured Patients with Persistent Gaps in Diabetes Care Services: The Translating Research into Action for Diabetes (TRIAD) Study 
Medical care  2010;48(1):31-37.
Although prevention of complications in diabetes requires careful control over many years, little is known about which patients persistently fail to get recommended care.
To determine the frequency and correlates of persistent long-term gaps in diabetes care.
Patient surveys and reviews of medical records were used to assess preventive care services for diabetes among 8392 patients who were continuously enrolled in 10 US managed care plans from 1999 to 2002. Demographic and socioeconomic characteristics, access to care, social support, and mental and physical health were determined by interview. Five preventive care services of diabetes care (testing of hemoglobin A1c, cholesterol, and albuminuria, dilated eye exams, and foot exams) were assessed by survey and chart abstraction for a 3-year period (1999–2002). We defined a “persistent lapse” as a participant’s missing a preventive care service for the entire 3 years.
In all, 70% of patients had no persistent lapses, 22% had 1, 6% had 2, and 2% had ≥ 3. Persistent lapses occurred most often for lipid testing (11.6%), microalbuminuria testing (9.7%), and eye exams (9.0%), but less frequently for foot exams (6.9%) and A1c tests (4.2%). In multivariate analyses, the odds of a persistent lapse in care was 42% higher for young (age 18–44) than middle aged persons and 26% higher among lean than very obese persons. In addition, the odds of a persistent lapse was 26% higher for those of low income, 29% higher among employed persons, 18% higher for smokers, 27% higher in those with fewer than 5 years of diabetes than those with > 15 years, and 42% higher for persons with zero or 1 comorbid conditions (compared to ≥ 3). In addition, non-Hispanic blacks were particularly likely to miss lipid tests (15.3%) and those not taking medications were especially likely to miss foot exams (7.1%), A1c tests (10.6%), and proteinuria tests (10.8%). Sex, education, marital status, family demands, transportation, trust in physicians, and mental health were not associated with lapses in care.
Even in an insured cohort, 3 in 10 participants had 1 or more persistent lapses in diabetes care. Patients with lower income, younger age, having fewer co-morbidities, taking fewer medications and poor health behaviors are particularly vulnerable to persistent lapses in care and a group who warrant targeted interventions to improve preventive diabetes care.
PMCID: PMC4269465  PMID: 20009778
2.  Trends in Death Rates Among U.S. Adults With and Without Diabetes Between 1997 and 2006 
Diabetes Care  2012;35(6):1252-1257.
To determine whether all-cause and cardiovascular disease (CVD) death rates declined between 1997 and 2006, a period of continued advances in treatment approaches and risk factor control, among U.S. adults with and without diabetes.
We compared 3-year death rates of four consecutive nationally representative samples (1997–1998, 1999–2000, 2001–2002, and 2003–2004) of U.S. adults aged 18 years and older using data from the National Health Interview Surveys linked to National Death Index.
Among diabetic adults, the CVD death rate declined by 40% (95% CI 23–54) and all-cause mortality declined by 23% (10–35) between the earliest and latest samples. There was no difference in the rates of decline in mortality between diabetic men and women. The excess CVD mortality rate associated with diabetes (i.e., compared with nondiabetic adults) decreased by 60% (from 5.8 to 2.3 CVD deaths per 1,000) while the excess all-cause mortality rate declined by 44% (from 10.8 to 6.1 deaths per 1,000).
Death rates among both U.S. men and women with diabetes declined substantially between 1997 and 2006, reducing the absolute difference between adults with and without diabetes. These encouraging findings, however, suggest that diabetes prevalence is likely to rise in the future if diabetes incidence is not curtailed.
PMCID: PMC3357247  PMID: 22619288
4.  Cost-Effectiveness of Alternative Thresholds of the Fasting Plasma Glucose Test to Identify the Target Population for Type 2 Diabetes Prevention in Adults Aged ≥45 Years 
Diabetes Care  2013;36(12):3992-3998.
The study objective was to evaluate the cost-effectiveness of alternative fasting plasma glucose (FPG) thresholds to identify adults at high risk for type 2 diabetes for diabetes preventive intervention.
We used a validated simulation model to examine the change in lifetime quality-adjusted life years (QALYs) and medical costs when the FPG threshold was progressively lowered in 5-mg/dL decrements from 120 to 90 mg/dL. The study sample includes nondiabetic adults aged ≥45 years in the United States using 2006–2010 data from the National Health and Nutrition Examination Survey. High-risk individuals were assumed to receive a lifestyle intervention, as that used in the Diabetes Prevention Program. We calculated cost per QALY by dividing the incremental cost by incremental QALY when lowering the threshold to the next consecutive level. Medical costs were assessed from a health care system perspective. We conducted univariate and probabilistic sensitivity analyses to assess the robustness of the results using different simulation scenarios and parameters.
Progressively lowering the FPG threshold would monotonically increase QALYs, cost, and cost per QALY. Reducing (in 5-mg/dL decrements) the threshold from 120 to 90 mg/dL cost $30,100, $32,900, $42,300, $60,700, $81,800, and $115,800 per QALY gained, respectively. The costs per QALY gained were lower for all thresholds under a lower-cost and less-effective intervention scenario.
Lowering the FPG threshold leads to a greater health benefit of diabetes prevention but reduces the cost-effectiveness. Using the conventional benchmark of $50,000 per QALY, a threshold of 105 mg/dL or higher would be cost effective. A lower threshold could be selected if the intervention cost could be lowered.
PMCID: PMC3836092  PMID: 24135386
5.  Secular Changes in the Age-Specific Prevalence of Diabetes Among U.S. Adults: 1988–2010 
Diabetes Care  2013;36(9):2690-2696.
To examine the age-specific changes of prevalence of diabetes among U.S. adults during the past 2 decades.
This study included 22,586 adults sampled in three periods of the National Health and Nutrition Examination Survey (1988–1994, 1999–2004, and 2005–2010). Diabetes was defined as having self-reported diagnosed diabetes or having a fasting plasma glucose level ≥126 mg/dL or HbA1c ≥6.5% (48 mmol/mol).
The number of adults with diabetes increased by 75% from 1988–1994 to 2005–2010. After adjusting for sex, race/ethnicity, and education level, the prevalence of diabetes increased over the two decades across all age-groups. Younger adults (20–34 years of age) had the lowest absolute increase in diabetes prevalence of 1.0%, followed by middle-aged adults (35–64) at 2.7% and older adults (≥65) at 10.0% (all P < 0.001). Comparing 2005–2010 with 1988–1994, the adjusted prevalence ratios (PRs) by age-group were 2.3, 1.3, and 1.5 for younger, middle-aged, and older adults, respectively (all P < 0.05). After additional adjustment for body mass index (BMI), waist-to-height ratio (WHtR), or waist circumference (WC), the adjusted PR remained statistically significant only for adults ≥65 years of age.
During the past two decades, the prevalence of diabetes increased across all age-groups, but adults ≥65 years of age experienced the largest increase in absolute change. Obesity, as measured by BMI, WHtR, or WC, was strongly associated with the increase in diabetes prevalence, especially in adults <65.
PMCID: PMC3747941  PMID: 23637354
6.  A Novel Use of Structural Equation Models to Examine Factors Associated With Prediabetes Among Adults Aged 50 Years and Older 
Diabetes Care  2013;36(9):2655-2662.
To use structural modeling to test a hypothesized model of causal pathways related with prediabetes among older adults in the U.S.
Cross-sectional study of 2,230 older adults (≥50 years) without diabetes included in the morning fasting sample of the 2001–2006 National Health and Nutrition Examination Surveys. Demographic data included age, income, marital status, race/ethnicity, and education. Behavioral data included physical activity (metabolic equivalent hours per week for vigorous or moderate muscle strengthening, walking/biking, and house/yard work), and poor diet (refined grains, red meat, added sugars, solid fats, and high-fat dairy). Structural-equation modeling was performed to examine the interrelationships among these variables with family history of diabetes, high blood pressure, BMI, large waist (waist circumference: women, ≥35 inches; men, ≥40 inches), triglycerides ≥200 mg/dL, and total and HDL (≥60 mg/dL) cholesterol.
After dropping BMI and total cholesterol, our best-fit model included three single factors: socioeconomic position (SEP), physical activity, and poor diet. Large waist had the strongest direct effect on prediabetes (0.279), followed by male sex (0.270), SEP (−0.157), high blood pressure (0.122), family history of diabetes (0.070), and age (0.033). Physical activity had direct effects on HDL (0.137), triglycerides (−0.136), high blood pressure (−0.132), and large waist (−0.067); poor diet had direct effects on large waist (0.146) and triglycerides (0.148).
Our results confirmed that, while including factors known to be associated with high risk of developing prediabetes, large waist circumference had the strongest direct effect. The direct effect of SEP on prediabetes suggests mediation by some unmeasured factor(s).
PMCID: PMC3747946  PMID: 23649617
7.  Socioeconomic and demographic predictors of selected cardiovascular risk factors among adults living in Pohnpei, Federated States of Micronesia 
BMC Public Health  2014;14(1):895.
The burden of cardiovascular disease (CVD) is increasing in low-to-middle income countries (LMIC). Although strong evidence for inverse associations between socioeconomic position and health outcomes in high-income countries exists, less is known about LMIC. Understanding country-level differences is critical to tailoring effective population health policy and interventions. We examined the association of socioeconomic position and demographic characteristics in determining CVD risk factors among adults living in Pohnpei, Federated States of Micronesia.
We used data from the cross-sectional World Health Organization’s STEPwise approach to surveillance 2002 Pohnpei dataset and logistic regression analyses to examine the association of socioeconomic position (education, income, employment) and demographics (age, sex) with selected behavioral and anthropometric CVD risk factors. The study sample consisted of 1638 adults (642 men, 996 women; 25–64 years).
In general, we found that higher education (≥13 years) was associated with lower odds for daily tobacco use (odds ratio [OR]: 0.46, confidence interval [CI]: 0.29–0.75, p = 0.004) and low physical activity (OR: 0.55, CI: 0.34–0.87, p = 0.027). Men had over three times the odds of daily tobacco use than women (OR: 3.18, CI: 2.29–4.43, p < 0.001). Among women, paid employment nearly doubled the odds of daily tobacco use (OR: 1.72, CI: 1.08–2.73, p = 0.006) than unemployment. For all participants, income > $10,000 was associated with over twice the odds of high blood pressure (BP) (OR: 2.24, CI: 1.43–3.51, p = 0.003), versus lower-income (<$5,000). Men had over twice the odds of high BP (OR: 2.01, CI: 1.43–2.83, p < 0.001) than women. Paid employment nearly doubled the odds of central obesity with the magnitude of association increasing by more than 20% adjusted for sex and age. Men reporting paid employment had three times the odds of central obesity (OR: 3.00, CI: 1.56–5.78, p < 0.001) than those unemployed.
Our analysis revealed associations between socioeconomic position and selected CVD risk factors, which varied by risk-factor, sex and age characteristics, and direction of association. The 2002 Pohnpei dataset provides country-level baseline information; further population health surveillance might define trends. Stronger country-level data might help decision-makers tailor population-based prevention strategies.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2458-14-895) contains supplementary material, which is available to authorized users.
PMCID: PMC4158138  PMID: 25175388
Micronesia; Health disparities; Chronic disease; Cardiovascular disease risk factors; Health determinants
8.  Secular Changes in U.S. Prediabetes Prevalence Defined by Hemoglobin A1c and Fasting Plasma Glucose 
Diabetes Care  2013;36(8):2286-2293.
Using a nationally representative sample of the civilian noninstitutionalized U.S. population, we estimated prediabetes prevalence and its changes during 1999–2010.
Data were from 19,182 nonpregnant individuals aged ≥12 years who participated in the 1999–2010 National Health and Nutrition Examination Surveys. We defined prediabetes as hemoglobin A1c (A1C) 5.7 to <6.5% (39 to <48 mmol/mol, A1C5.7) or fasting plasma glucose (FPG) 100 to <126 mg/dL (impaired fasting glucose [IFG]). We estimated the prevalence of prediabetes, A1C5.7, and IFG for 1999–2002, 2003–2006, and 2007–2010. We calculated estimates age-standardized to the 2000 U.S. census population and used logistic regression to compute estimates adjusted for age, sex, race/ethnicity, poverty-to-income ratio, and BMI. Participants with self-reported diabetes, A1C ≥6.5% (≥48 mmol/mol), or FPG ≥126 mg/dL were included.
Among those aged ≥12 years, age-adjusted prediabetes prevalence increased from 27.4% (95% CI 25.1–29.7) in 1999–2002 to 34.1% (32.5–35.8) in 2007–2010. Among adults aged ≥18 years, the prevalence increased from 29.2% (26.8–31.8) to 36.2% (34.5–38.0). As single measures among individuals aged ≥12 years, A1C5.7 prevalence increased from 9.5% (8.4–10.8) to 17.8% (16.6–19.0), a relative increase of 87%, whereas IFG remained stable. These prevalence changes were similar among the total population, across subgroups, and after controlling for covariates.
During 1999–2010, U.S. prediabetes prevalence increased because of increases in A1C5.7. Continuous monitoring of prediabetes is needed to identify, quantify, and characterize the population of high-risk individuals targeted for ongoing diabetes primary prevention efforts.
PMCID: PMC3714534  PMID: 23603918
9.  Modeling the impact of prevention policies on future diabetes prevalence in the United States: 2010–2030 
Although diabetes is one of the most costly and rapidly increasing serious chronic diseases worldwide, the optimal mix of strategies to reduce diabetes prevalence has not been determined.
Using a dynamic model that incorporates national data on diabetes prevalence and incidence, migration, mortality rates, and intervention effectiveness, we project the effect of five hypothetical prevention policies on future US diabetes rates through 2030: 1) no diabetes prevention strategy; 2) a “high-risk” strategy, wherein adults with both impaired fasting glucose (IFG) (fasting plasma glucose of 100–124 mg/dl) and impaired glucose tolerance (IGT) (2-hour post-load glucose of 141–199 mg/dl) receive structured lifestyle intervention; 3) a “moderate-risk” strategy, wherein only adults with IFG are offered structured lifestyle intervention; 4) a “population-wide” strategy, in which the entire population is exposed to broad risk reduction policies; and 5) a “combined” strategy, involving both the moderate-risk and population-wide strategies. We assumed that the moderate- and high-risk strategies reduce the annual diabetes incidence rate in the targeted subpopulations by 12.5% through 2030 and that the population-wide approach would reduce the projected annual diabetes incidence rate by 2% in the entire US population.
We project that by the year 2030, the combined strategy would prevent 4.6 million incident cases and 3.6 million prevalent cases, attenuating the increase in diabetes prevalence by 14%. The moderate-risk approach is projected to prevent 4.0 million incident cases, 3.1 million prevalent cases, attenuating the increase in prevalence by 12%. The high-risk and population approaches attenuate the projected prevalence increases by 5% and 3%, respectively. Even if the most effective strategy is implemented (the combined strategy), our projections indicate that the diabetes prevalence rate would increase by about 65% over the 23 years (i.e., from 12.9% in 2010 to 21.3% in 2030).
While implementation of appropriate diabetes prevention strategies may slow the rate of increase of the prevalence of diabetes among US adults through 2030, the US diabetes prevalence rate is likely to increase dramatically over the next 20 years. Demand for health care services for people with diabetes complications and diabetes-related disability will continue to grow, and these services will need to be strengthened along with primary diabetes prevention efforts.
PMCID: PMC3853008  PMID: 24047329
10.  Prevalence of Diagnosed Arthritis and Arthritis-Attributable Activity Limitation Among Adults With and Without Diagnosed Diabetes: United States, 2008–2010 
Diabetes Care  2012;35(8):1686-1691.
To estimate the prevalence of diagnosed arthritis among U.S. adults and the proportion of arthritis-attributable activity limitation (AAAL) among those with arthritis by diagnosed diabetes mellitus (DM) status.
We estimated prevalences and their ratios using 2008–2010 U.S. National Health Interview Survey of noninstitutionalized U.S. adults aged ≥18 years. Respondents’ arthritis and DM status were both based on whether they reported a diagnosis of these diseases. Other characteristics used for stratification or adjustment included age, sex, race/ethnicity, education level, BMI, and physical activity level.
Among adults with DM, the unadjusted prevalences of arthritis and proportion of AAAL among adults with arthritis (national estimated cases in parentheses) were 48.1% (9.6 million) and 55.0% (5.3 million), respectively. After adjusting for other characteristics, the prevalence ratios of arthritis and of AAAL among arthritic adults with versus without DM (95% CI) were 1.44 (1.35–1.52) and 1.21 (1.15–1.28), respectively. The prevalence of arthritis increased with age and BMI and was higher for women, non-Hispanic whites, and inactive adults compared with their counterparts both among adults with and without DM (all P values < 0.05). Among adults with diagnosed DM and arthritis, the proportion of AAAL was associated with being obese, but was not significantly associated with age, sex, and race/ethnicity.
Among U.S. adults with diagnosed DM, nearly half also have diagnosed arthritis; moreover, more than half of those with both diseases had AAAL. Arthritis can be a barrier to physical activity among adults with diagnosed DM.
PMCID: PMC3402271  PMID: 22688544
11.  Access to Health Care and Control of ABCs of Diabetes 
Diabetes Care  2012;35(7):1566-1571.
To examine the relationship between access to health care and diabetes control.
Using data from the National Health and Nutrition Examination Survey, 1999–2008, we identified 1,221 U.S. adults (age 18–64 years) with self-reported diabetes. Access was measured by current health insurance coverage, number of times health care was received over the past year, and routine place to go for health care. Diabetes control measures included the proportion of people with A1C >9%, blood pressure ≥140/90 mmHg, and non-HDL cholesterol ≥130 mg/dL.
An estimated 16.0% of known diabetic adults were uninsured. Diabetes control profiles were worse among uninsured than among insured persons (A1C >9% [34.1 vs. 16.5%, P = 0.002], blood pressure ≥140/90 mmHg [31.8 vs. 22.8%, P < 0.05], and non-HDL cholesterol ≥130 mg/dL [67.1 vs. 65.4%, P = 0.7]). Compared with insured persons, uninsured persons were more likely to have A1C >9% (multivariate-adjusted odds ratio 2.4 [95% CI 1.2–4.7]). Compared with those who reported four or more health care visits in the past year, those who reported no health care visits were more likely to have A1C >9% (5.5 [1.2–26.3]) and blood pressure ≥140/90 mmHg (1.9 [1.1–3.4]).
In people with diabetes, lack of health care coverage is associated with poor glycemic control. In addition, low use of health care service is associated with poor glucose and blood pressure control.
PMCID: PMC3379598  PMID: 22522664
12.  Prevalence of Diabetes and Intermediate Hyperglycemia Among Adults From the First Multinational Study of Noncommunicable Diseases in Six Central American Countries 
Diabetes Care  2012;35(4):738-740.
The increasing burdens of obesity and diabetes are two of the most prominent threats to the health of populations of developed and developing countries alike. The Central America Diabetes Initiative (CAMDI) is the first study to examine the prevalence of diabetes in Central America.
The CAMDI survey was a cross-sectional survey based on a probabilistic sample of the noninstitutionalized population of five Central American populations conducted between 2003 and 2006. The total sample population was 10,822, of whom 7,234 (67%) underwent anthropometry measurement and a fasting blood glucose or 2-h oral glucose tolerance test.
The total prevalence of diabetes was 8.5%, but was higher in Belize (12.9%) and lower in Honduras (5.4%). Of the screened population, 18.6% had impaired glucose tolerance/impaired fasting glucose.
As this population ages, the prevalence of diabetes is likely to continue to rise in a dramatic and devastating manner. Preventive strategies must be quickly introduced.
PMCID: PMC3308278  PMID: 22323417
13.  Declining Rates of Hospitalization for Nontraumatic Lower-Extremity Amputation in the Diabetic Population Aged 40 Years or Older: U.S., 1988–2008 
Diabetes Care  2012;35(2):273-277.
To assess trends in rates of hospitalization for nontraumatic lower-extremity amputation (NLEA) in U.S. diabetic and nondiabetic populations and disparities in NLEA rates within the diabetic population.
We calculated NLEA hospitalization rates, by diabetes status, among persons aged ≥40 years on the basis of National Hospital Discharge Survey data on NLEA procedures and National Health Interview Survey data on diabetes prevalence. We used joinpoint regression to calculate the annual percentage change (APC) and to assess trends in rates from 1988 to 2008.
The age-adjusted NLEA discharge rate per 1,000 persons among those diagnosed with diabetes and aged ≥40 years decreased from 11.2 in 1996 to 3.9 in 2008 (APC −8.6%; P < 0.01), while rates among persons without diagnosed diabetes changed little. NLEA rates in the diabetic population decreased significantly from 1996 to 2008 in all demographic groups examined (all P < 0.05). Throughout the entire study period, rates of diabetes-related NLEA were higher among persons aged ≥75 years than among those who were younger, higher among men than women, and higher among blacks than whites.
From 1996 to 2008, NLEA discharge rates declined significantly in the U.S. diabetic population. Nevertheless, NLEA continues to be substantially higher in the diabetic population than in the nondiabetic population and disproportionately affects people aged ≥75 years, blacks, and men. Continued efforts are needed to decrease the prevalence of NLEA risk factors and to improve foot care among certain subgroups within the U.S. diabetic population that are at higher risk.
PMCID: PMC3263875  PMID: 22275440
14.  Lifestyle Change and Mobility in Obese Adults with Type 2 Diabetes 
The New England Journal of Medicine  2012;366(13):1209-1217.
Adults with type 2 diabetes mellitus often have limitations in mobility that increase with age. An intensive lifestyle intervention that produces weight loss and improves fitness could slow the loss of mobility in such patients.
We randomly assigned 5145 overweight or obese adults between the ages of 45 and 74 years with type 2 diabetes to either an intensive lifestyle intervention or a diabetes support-and-education program; 5016 participants contributed data. We used hidden Markov models to characterize disability states and mixed-effects ordinal logistic regression to estimate the probability of functional decline. The primary outcome was self-reported limitation in mobility, with annual assessments for 4 years.
At year 4, among 2514 adults in the lifestyle-intervention group, 517 (20.6%) had severe disability and 969 (38.5%) had good mobility; the numbers among 2502 participants in the support group were 656 (26.2%) and 798 (31.9%), respectively. The lifestyle-intervention group had a relative reduction of 48% in the risk of loss of mobility, as compared with the support group (odds ratio, 0.52; 95% confidence interval, 0.44 to 0.63; P<0.001). Both weight loss and improved fitness (as assessed on treadmill testing) were significant mediators of this effect (P<0.001 for both variables). Adverse events that were related to the lifestyle intervention included a slightly higher frequency of musculoskeletal symptoms at year 1.
Weight loss and improved fitness slowed the decline in mobility in overweight adults with type 2 diabetes. (Funded by the Department of Health and Human Services and others; number, NCT00017953.)
PMCID: PMC3339039  PMID: 22455415
15.  Long-Term and Recent Progress in Blood Pressure Levels Among U.S. Adults With Diagnosed Diabetes, 1988–2008 
Diabetes Care  2011;34(7):1579-1581.
To examine whether there were long-term (between 1988–1994 and 2001–2008) and recent (between 2001–2004 and 2005–2008) changes in blood pressure (BP) levels among U.S. adults with diagnosed diabetes.
Using data from National Health and Nutrition Examination Surveys (NHANES), we examined changes in BP distributions, mean BPs, and proportion with BP <140/90 mmHg.
Between 1988–1994 and 2001–2008, for adults with diabetes, mean BPs decreased from 135/72 mmHg to 131/69 mmHg (P < 0.01) and the proportion with BP <140/90 mmHg increased from 64 to 69% (P = 0.01). Although hypertension prevalence increased, hypertension awareness, treatment, and control improved. However, there was no evidence of improvement for adults 20–44 years old. Between 2001–2004 and 2005–2008, there were no significant changes in BP levels.
BP levels among adults with diabetes improved between 1988–1994 and 2001–2008, but the progress stalled between 2001–2004 and 2005–2008. The lack of improvement among young adults is concerning.
PMCID: PMC3120172  PMID: 21602427
16.  Implications of Alternative Definitions of Prediabetes for Prevalence in U.S. Adults 
Diabetes Care  2011;34(2):387-391.
To compare the prevalence of prediabetes using A1C, fasting plasma glucose (FPG), and oral glucose tolerance test (OGTT) criteria, and to examine the degree of agreement between the measures.
We used the 2005–2008 National Health and Nutrition Examination Surveys to classify 3,627 adults aged ≥18 years without diabetes according to their prediabetes status using A1C, FPG, and OGTT. We compared the prevalence of prediabetes according to different measures and used conditional probabilities to examine agreement between measures.
In 2005–2008, the crude prevalence of prediabetes in adults aged ≥18 years was 14.2% for A1C 5.7–6.4% (A1C5.7), 26.2% for FPG 100–125 mg/dL (IFG100), 7.0% for FPG 110–125 mg/dL (IFG110), and 13.7% for OGTT 140–199 mg/dL (IGT). Prediabetes prevalence varied by age, sex, and race/ethnicity, and there was considerable discordance between measures of prediabetes. Among those with IGT, 58.2, 23.4, and 32.3% had IFG100, IFG110, and A1C5.7, respectively, and 67.1% had the combination of either A1C5.7 or IFG100.
The prevalence of prediabetes varied by the indicator used to measure risk; there was considerable discordance between indicators and the characteristics of individuals with prediabetes. Programs to prevent diabetes may need to consider issues of equity, resources, need, and efficiency in targeting their efforts.
PMCID: PMC3024354  PMID: 21270196
18.  Prevalence of Diabetic Retinopathy in the United States, 2005–2008 
The prevalence of diabetes in the United States has increased. People with diabetes are at risk for diabetic retinopathy. No recent national population-based estimate of the prevalence and severity of diabetic retinopathy exists.
To describe the prevalence and risk factors of diabetic retinopathy among US adults with diabetes aged 40 years and older.
Design, Setting, and Participants
Analysis of a cross-sectional, nationally representative sample of the National Health and Nutrition Examination Survey 2005–2008 (N=1006). Diabetes was defined as a self-report of a previous diagnosis of the disease (excluding gestational diabetes mellitus) or glycated hemoglobin A1c of 6.5% or greater. Two fundus photographs were taken of each eye with a digital nonmydriatic camera and were graded using the Airlie House classification scheme and the Early Treatment Diabetic Retinopathy Study severity scale. Prevalence estimates were weighted to represent the civilian, noninstitutionalized US population aged 40 years and older.
Main Outcome Measurements
Diabetic retinopathy and vision-threatening diabetic retinopathy.
The estimated prevalence of diabetic retinopathy and vision-threatening diabetic retinopathy was 28.5% (95% confidence interval [CI], 24.9%–32.5%) and 4.4% (95% CI, 3.5%–5.7%) among US adults with diabetes, respectively. Diabetic retinopathy was slightly more prevalent among men than women with diabetes (31.6%; 95% CI, 26.8%–36.8%; vs 25.7%; 95% CI, 21.7%–30.1%; P=.04). Non-Hispanic black individuals had a higher crude prevalence than non-Hispanic white individuals of diabetic retinopathy (38.8%; 95% CI, 31.9%–46.1%; vs 26.4%; 95% CI, 21.4%–32.2%; P=.01) and vision-threatening diabetic retinopathy (9.3%; 95% CI, 5.9%–14.4%; vs 3.2%; 95% CI, 2.0%–5.1%; P=.01). Male sex was independently associated with the presence of diabetic retinopathy (odds ratio [OR], 2.07; 95% CI, 1.39–3.10), as well as higher hemoglobin A1c level (OR, 1.45; 95% CI, 1.20–1.75), longer duration of diabetes (OR, 1.06 per year duration; 95% CI, 1.03–1.10), insulin use (OR, 3.23; 95% CI, 1.99–5.26), and higher systolic blood pressure (OR, 1.03 per mm Hg; 95% CI, 1.02–1.03).
In a nationally representative sample of US adults with diabetes aged 40 years and older, the prevalence of diabetic retinopathy and vision-threatening diabetic retinopathy was high, especially among Non-Hispanic black individuals.
PMCID: PMC2945293  PMID: 20699456
20.  Prevalence and Predictors of Abnormal Cardiovascular Responses to Exercise Testing Among Individuals With Type 2 Diabetes 
Diabetes Care  2010;33(4):901-907.
We examined maximal graded exercise test (GXT) results in 5,783 overweight/obese men and women, aged 45–76 years, with type 2 diabetes, who were entering the Look AHEAD (Action for Health in Diabetes) study, to determine the prevalence and correlates of exercise-induced cardiac abnormalities.
Participants underwent symptom-limited maximal GXTs. Questionnaires and physical examinations were used to determine demographic, anthropometric, metabolic, and health status predictors of abnormal GXT results, which were defined as an ST segment depression ≥1.0 mm, ventricular arrhythmia, angina pectoris, poor postexercise heart rate recovery (<22 bpm reduction 2 min after exercise), or maximal exercise capacity less than 5.0 METs. Systolic blood pressure response to exercise was examined as a continuous variable, without a threshold to define abnormality.
Exercise-induced abnormalities were present in 1,303 (22.5%) participants, of which 693 (12.0%) consisted of impaired exercise capacity. ST segment depression occurred in 440 (7.6%), abnormal heart rate recovery in 206 (5.0%), angina in 63 (1.1%), and arrhythmia in 41 (0.7%). Of potential predictors, only greater age was associated with increased prevalence of all abnormalities. Other predictors were associated with some, but not all, abnormalities. Systolic blood pressure response decreased with greater age, duration of diabetes, and history of cardiovascular disease.
We found a high rate of abnormal GXT results despite careful screening for cardiovascular disease symptoms. In this cohort of overweight and obese individuals with type 2 diabetes, greater age most consistently predicted abnormal GXT. Long-term follow-up of these participants will show whether these abnormalities are clinically significant.
PMCID: PMC2845049  PMID: 20056948
21.  Prevalence of Diabetes and High Risk for Diabetes Using A1C Criteria in the U.S. Population in 1988–2006 
Diabetes Care  2010;33(3):562-568.
We examined prevalences of previously diagnosed diabetes and undiagnosed diabetes and high risk for diabetes using recently suggested A1C criteria in the U.S. during 2003–2006. We compared these prevalences to those in earlier surveys and those using glucose criteria.
In 2003–2006, the National Health and Nutrition Examination Survey included a probability sample of 14,611 individuals aged ≥12 years. Participants were classified on glycemic status by interview for diagnosed diabetes and by A1C, fasting, and 2-h glucose challenge values measured in subsamples.
Using A1C criteria, the crude prevalence of total diabetes in adults aged ≥20 years was 9.6% (20.4 million), of which 19.0% was undiagnosed (7.8% diagnosed, 1.8% undiagnosed using A1C ≥6.5%). Another 3.5% of adults (7.4 million) were at high risk for diabetes (A1C 6.0 to <6.5%). Prevalences were disproportionately high in the elderly. Age-/sex-standardized prevalence was more than two times higher in non-Hispanic blacks and Mexican Americans versus non-Hispanic whites for diagnosed, undiagnosed, and total diabetes (P < 0.003); standardized prevalence at high risk for diabetes was more than two times higher in non-Hispanic blacks versus non-Hispanic whites and Mexican Americans (P < 0.00001). Since 1988–1994, diagnosed diabetes generally increased, while the percent of diabetes that was undiagnosed and the percent at high risk of diabetes generally decreased. Using A1C criteria, prevalences of undiagnosed diabetes and high risk of diabetes were one-third that and one-tenth that, respectively, using glucose criteria.
Although A1C detects much lower prevalences than glucose criteria, hyperglycemic conditions remain high in the U.S., and elderly and minority groups are disproportionately affected.
PMCID: PMC2827508  PMID: 20067953
22.  Association of A1C and Fasting Plasma Glucose Levels With Diabetic Retinopathy Prevalence in the U.S. Population 
Diabetes Care  2009;32(11):2027-2032.
To examine the association of A1C levels and fasting plasma glucose (FPG) with diabetic retinopathy in the U.S. population and to compare the ability of the two glycemic measures to discriminate between people with and without retinopathy.
This study included 1,066 individuals aged ≥40 years from the 2005–2006 National Health and Nutrition Examination Survey. A1C, FPG, and 45° color digital retinal images were assessed. Retinopathy was defined as a level ≥14 on the Early Treatment Diabetic Retinopathy Study severity scale. We used joinpoint regression to identify linear inflections of prevalence of retinopathy in the association between A1C and FPG.
The overall prevalence of retinopathy was 11%, which is appreciably lower than the prevalence in people with diagnosed diabetes (36%). There was a sharp increase in retinopathy prevalence in those with A1C ≥5.5% or FPG ≥5.8 mmol/l. After excluding 144 people using hypoglycemic medication, the change points for the greatest increase in retinopathy prevalence were A1C 5.5% and FPG 7.0 mmol/l. The coefficients of variation were 15.6 for A1C and 28.8 for FPG. Based on the areas under the receiver operating characteristic curves, A1C was a stronger discriminator of retinopathy (0.71 [95% CI 0.66–0.76]) than FPG (0.65 [0.60 – 0.70], P for difference = 0.009).
The steepest increase in retinopathy prevalence occurs among individuals with A1C ≥5.5% and FPG ≥5.8 mmol/l. A1C discriminates prevalence of retinopathy better than FPG.
PMCID: PMC2768189  PMID: 19875604
23.  Projection of the year 2050 burden of diabetes in the US adult population: dynamic modeling of incidence, mortality, and prediabetes prevalence 
People with diabetes can suffer from diverse complications that seriously erode quality of life. Diabetes, costing the United States more than $174 billion per year in 2007, is expected to take an increasingly large financial toll in subsequent years. Accurate projections of diabetes burden are essential to policymakers planning for future health care needs and costs.
Using data on prediabetes and diabetes prevalence in the United States, forecasted incidence, and current US Census projections of mortality and migration, the authors constructed a series of dynamic models employing systems of difference equations to project the future burden of diabetes among US adults. A three-state model partitions the US population into no diabetes, undiagnosed diabetes, and diagnosed diabetes. A four-state model divides the state of "no diabetes" into high-risk (prediabetes) and low-risk (normal glucose) states. A five-state model incorporates an intervention designed to prevent or delay diabetes in adults at high risk.
The authors project that annual diagnosed diabetes incidence (new cases) will increase from about 8 cases per 1,000 in 2008 to about 15 in 2050. Assuming low incidence and relatively high diabetes mortality, total diabetes prevalence (diagnosed and undiagnosed cases) is projected to increase from 14% in 2010 to 21% of the US adult population by 2050. However, if recent increases in diabetes incidence continue and diabetes mortality is relatively low, prevalence will increase to 33% by 2050. A middle-ground scenario projects a prevalence of 25% to 28% by 2050. Intervention can reduce, but not eliminate, increases in diabetes prevalence.
These projected increases are largely attributable to the aging of the US population, increasing numbers of members of higher-risk minority groups in the population, and people with diabetes living longer. Effective strategies will need to be undertaken to moderate the impact of these factors on national diabetes burden. Our analysis suggests that widespread implementation of reasonably effective preventive interventions focused on high-risk subgroups of the population can considerably reduce, but not eliminate, future increases in diabetes prevalence.
PMCID: PMC2984379  PMID: 20969750
24.  Full Accounting of Diabetes and Pre-Diabetes in the U.S. Population in 1988–1994 and 2005–2006  
Diabetes Care  2009;32(2):287-294.
OBJECTIVE—We examined the prevalences of diagnosed diabetes, and undiagnosed diabetes and pre-diabetes using fasting and 2-h oral glucose tolerance test values, in the U.S. during 2005–2006. We then compared the prevalences of these conditions with those in 1988–1994.
RESEARCH DESIGN AND METHODS—In 2005–2006, the National Health and Nutrition Examination Survey included a probability sample of 7,267 people aged ≥12 years. Participants were classified according to glycemic status by interview for diagnosed diabetes and by fasting and 2-h glucoses measured in subsamples.
RESULTS—In 2005–2006, the crude prevalence of total diabetes in people aged ≥20 years was 12.9%, of which ∼40% was undiagnosed. In people aged ≥20 years, the crude prevalence of impaired fasting glucose was 25.7% and of impaired glucose tolerance was 13.8%, with almost 30% having either. Over 40% of individuals had diabetes or pre-diabetes. Almost one-third of the elderly had diabetes, and three-quarters had diabetes or pre-diabetes. Compared with non-Hispanic whites, age- and sex-standardized prevalence of diagnosed diabetes was approximately twice as high in non-Hispanic blacks (P < 0.0001) and Mexican Americans (P = 0.0001), whereas undiagnosed diabetes was not higher. Crude prevalence of diagnosed diabetes in people aged ≥20 years rose from 5.1% in 1988–1994 to 7.7% in 2005–2006 (P = 0.0001); this was significant after accounting for differences in age and sex, particularly in non-Hispanic blacks. Prevalences of undiagnosed diabetes and pre-diabetes were generally stable, although the proportion of total diabetes that was undiagnosed decreased in Mexican Americans.
CONCLUSIONS—Over 40% of people aged ≥20 years have hyperglycemic conditions, and prevalence is higher in minorities. Diagnosed diabetes has increased over time, but other conditions have been relatively stable.
PMCID: PMC2628695  PMID: 19017771
25.  Control of Risk Factors Among People With Diagnosed Diabetes, by Lower Extremity Disease Status 
Preventing Chronic Disease  2009;6(4):A114.
We examined the control of modifiable risk factors among a national sample of diabetic people with and without lower extremity disease (LED).
The sample from the 1999-2004 National Health and Nutrition Examination Survey consisted of 948 adults aged 40 years or older with diagnosed diabetes and who had been assessed for LED. LED was defined as peripheral arterial disease (ankle-brachial index <0.9), peripheral neuropathy (≥1 insensate area), or presence of foot ulcer. Good control of modifiable risk factors, based on American Diabetes Association recommendations, included being a nonsmoker and having the following measurements: HbA1c less than 7%, systolic blood pressure less than or equal to 130 mm Hg, diastolic blood pressure less than or equal to 80 mm Hg, high density lipoprotein (HDL) cholesterol greater than 50 mg/dL, and body mass index (BMI) between 18.5 kg/m2 and 24.9 kg/m2.
Diabetic people with LED were less likely than were people without LED to have recommended levels of HbA1c (39.3% vs 53.5%) and HDL cholesterol (29.7% vs 41.1%), but there were no differences in systolic or diastolic blood pressure, BMI classification, or smoking status between people with and without LED. Control of some risk factors differed among population subgroups. Notably, among diabetic people with LED, non-Hispanic blacks were more likely to have improper control of HbA1c (adjusted odds ratio [AOR] = 2.0; 95% confidence interval [CI], 1.1-3.9), systolic blood pressure (AOR = 1.9; 95% CI, 1.1-3.2), and diastolic blood pressure (AOR = 2.6; 95% CI, 1.1-5.8), compared with non-Hispanic whites.
Control of 2 of 6 modifiable risk factors was worse in diabetic adults with LED compared with diabetic adults without LED. Among diabetic people with LED, non-Hispanic blacks had worse control of 3 of 6 risk factors compared with non-Hispanic whites.
PMCID: PMC2774628  PMID: 19754990

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