We tested the hypothesis that altered Toll-like receptor (TLR) signaling may be involved in early stages of type 1 diabetes (T1D). To do so, we analyzed TLR-induced interleukin (IL)-1β and IL-6 responses in freshly isolated peripheral blood mononuclear cells (PBMNCs) from seropositive compared with seronegative subjects. Similar frequencies of myeloid dendritic cells (mDCs), plasmacytoid DCs (pDCs), and monocytes were observed in seropositive and seronegative subjects. Subjects with autoantibodies had increased proportions of monocytes expressing IL-1β ex vivo. Activating PBMNCs with TLR3, TLR4, or TLR7/8 agonists in vitro led to increased percentages of IL-1β–expressing monocytes and mDCs from seropositive versus seronegative subjects. TLR ligation also resulted in a diminished IL-6 response in seropositive individuals as lower frequencies of IL-6–expressing monocytes and mDCs were induced. The dysregulated TLR-induced IL-1β and IL-6 pathways were more readily detectable in children aged <11 years and from 11 to <21 years, respectively, and did not involve altered HbA1c or the presence of one or more autoantibodies. Finally, subjects with autoantibodies had lower amounts of serum chemokine (C-X-C motif) ligand 10 compared with autoantibody-negative subjects. Our data may imply that alterations in innate immune pathways are detectable in genetically susceptible individuals and could be linked with the early course of T1D.
The aim of this study was to evaluate HbA1c as an alternative criterion for impaired glucose tolerance (IGT) or type 1 diabetes (T1D) in high-risk subjects <21 years of age.
RESEARCH DESIGN AND METHODS
Subjects <21 years of age who participated in the prospective DPT-1, TEDDY, TRIGR, and Type 1 Diabetes TrialNet Natural History (TrialNet) studies and had an HbA1c within 90 days of an OGTT with a 2-h plasma glucose (2-hPG) measure were included. An OGTT of 140–199 mg/dL defined IGT, and an OGTT with 2-hPG ≥200 mg/dL or fasting plasma glucose ≥126 mg/dL defined diabetes. HbA1c ≥5.7% defined IGT, and HbA1c ≥ 6.5% defined diabetes. Receiver-operating characteristic curve analysis was used to assess diagnostic accuracy of HbA1c compared with OGTT.
There were 587 subjects from DPT-1, 884 from TrialNet, 91 from TEDDY, and 420 from TRIGR. As an indicator for IGT, HbA1c sensitivity was very low across the studies (8–42%), and specificity was variable (64–95%). With HbA1c ≥6.5% threshold used for T1D diagnosis, the sensitivity was very low and specificity was high (sensitivity and specificity: DPT-1 24 and 98%, TrialNet 28 and 99%, TEDDY 34 and 98%, and TRIGR 33 and 99%, respectively). The positive predictive value of HbA1c ≥6.5% for the development of T1D was variable (50–94%) across the four studies.
HbA1c ≥6.5% is a specific but not sensitive early indicator for T1D in high-risk subjects <21 years of age diagnosed by OGTT or asymptomatic hyperglycemia. Redefining the HbA1c threshold is recommended if used as an alternative criterion in diagnosing T1D.
Haptoglobin (Hp) is an abundant serum protein which binds extracorpuscular hemoglobin (Hb). Two alleles exist in humans for the Hp gene, denoted 1 and 2. Diabetic individuals with the Hp 2-2 genotype are at increased risk of developing vascular complications including heart attack, stroke, and kidney disease. Recent evidence shows that treatment with vitamin E can reduce the risk of diabetic vascular complications by as much as 50% in Hp 2-2 individuals. We sought to develop a rapid and accurate test for Hp phenotype (which is 100% concordant with the three major Hp genotypes) to facilitate widespread diagnostic testing as well as prospective clinical trials.
A monoclonal antibody raised against human Hp was shown to distinguish between the three Hp phenotypes in an enzyme linked immunosorbent assay (ELISA). Hp phenotypes obtained in over 8000 patient samples using this ELISA method were compared with those obtained by polyacrylamide gel electrophoresis or the TaqMan PCR method.
Our analysis showed that the sensitivity and specificity of the ELISA test for Hp 2-2 phenotype is 99.0% and 98.1%, respectively. The positive predictive value and the negative predictive value for Hp 2-2 phenotype is 97.5% and 99.3%, respectively. Similar results were obtained for Hp 2-1 and Hp 1-1 phenotypes. In addition, the ELISA was determined to be more sensitive and specific than the TaqMan method.
The Hp ELISA represents a user-friendly, rapid and highly accurate diagnostic tool for determining Hp phenotypes. This test will greatly facilitate the typing of thousands of samples in ongoing clinical studies.
diabetes; ELISA; haptoglobin phenotype; pharmacogenomics; vitamin E
Proteomics analysis identifies human serum proteins involved with innate immune responses, complement activation, and blood coagulation that are diagnostic for type 1 diabetes.
Using global liquid chromatography-mass spectrometry (LC-MS)–based proteomics analyses, we identified 24 serum proteins that were significantly variant between those with type 1 diabetes (T1D) and healthy controls. Functionally, these proteins represent innate immune responses, the activation cascade of complement, inflammatory responses, and blood coagulation. Targeted verification analyses were performed on 52 surrogate peptides representing these proteins, with serum samples from an antibody standardization program cohort of 100 healthy control and 50 type 1 diabetic subjects. 16 peptides were verified as having very good discriminating power, with areas under the receiver operating characteristic curve ≥0.8. Further validation with blinded serum samples from an independent cohort (10 healthy control and 10 type 1 diabetics) demonstrated that peptides from platelet basic protein and C1 inhibitor achieved both 100% sensitivity and 100% specificity for classification of samples. The disease specificity of these proteins was assessed using sera from 50 age-matched type 2 diabetic individuals, and a subset of proteins, C1 inhibitor in particular, were exceptionally good discriminators between these two forms of diabetes. The panel of biomarkers distinguishing those with T1D from healthy controls and those with type 2 diabetes suggests that dysregulated innate immune responses may be associated with the development of this disorder.
We recently reported an association with type 1 diabetes of a telomeric MHC SNP rs1233478. As further families have been analyzed in the Type 1 Diabetes Genetics Consortium (T1DGC), we sought to test replication of the association and with more data analyze haplotypic associations.
Research Design and Methods
We have since analyzed an additional 2,717 case and 1,315 control chromosomes from the T1DGC, with HLA-typing and data for 2,837 SNPs across the MHC region.
We confirmed the association of rs1233478 [new data only: p=2.2E-5, OR=1.4]. We also found two additional SNPs nearby which were significantly associated with type 1 diabetes (new data only rs3131020: p=8.3E-9, OR=0.65; rs1592410 p=2.2E-8, OR=1.5). For studies of type 1 diabetes in the MHC region it is critical to account for linkage disequilibrium with the HLA genes. Logistic regression analysis of this new data indicated that the effects of rs3131020 and rs1592410 on type 1 diabetes risk are independent of HLA alleles (rs3131020: p=2.3E-3, OR=0.73; rs1592410: p=2.1E-3, OR=1.4). Haplotypes of 12 SNPs (including the three highly significant SNPs) stratify diabetes risk (high risk, protective, and neutral), with high risk haplotypes limited to approximately 20,000 base pairs in length. The 20,000 base pair region is telomeric of the UBD gene and contains LOC729653, a hypothetical gene.
We believe that polymorphisms of the telomeric MHC locus LOC729653 may confer risk for type 1 diabetes.
genetic association studies; major histocompatibility complex; type 1 diabetes
The Environmental Determinants of Diabetes in the Young (TEDDY), a multinational epidemiological study, is designed to identify environmental exposures triggering autoimmunity and type 1 diabetes (T1D) in children at increased genetic risk. The objective of this analysis was to evaluate the use of an informational video in the enrollment and retention of eligible participants at the Colorado TEDDY clinical center.
Study Design and Setting
Eligible participants were divided into two groups based on the inclusion of the video in the enrollment materials: the No-Video Group (n=449) did not receive the video and were contacted between 7/1/07 and 6/30/08. The Video Group (n=494) received the video and were contacted between 7/1/08 and 6/30/09. Multiple logistic regression compared the enrollment rates (percent of eligible subjects deciding to enroll) of those who received the video compared to those who did not. Kaplan-Meier survival analysis and a multivariate Cox proportional hazards model compared the differences in study retention, as defined by active participation fifteen months after the baseline visit at three months of age.
Both groups were demographically similar. The enrollment rate was significantly higher for the Video Group (56.9%) compared to the No-Video Group (49.9%). Differences remained significant with adjustment for other known factors. A difference in retention between the two groups was not observed.
Methods and materials increasing understanding and more accurately informing participants of what is involved in participation may increase enrollment in a prospective observational study.
pediatric observational study; enrollment; informed consent; video methods; type 1 diabetes mellitus
We assessed the effects of non-HLA gene polymorphisms on the risk of islet autoimmunity (IA) and progression to type 1 diabetes in the Diabetes Autoimmunity Study in the Young. A total of 1,743 non-Hispanic, white children were included: 861 first-degree relatives and 882 general population children identified as having high-risk HLA-DR/DQ genotypes for type 1 diabetes. Of those, 109 developed IA and 61 progressed to diabetes. Study participants were genotyped for 20 non-HLA polymorphisms, previously confirmed as type 1 diabetes susceptibility loci. PTPN22 and UBASH3A predicted both IA and diabetes in regression models controlling for family history of type 1 diabetes and presence of HLA-DR3/4-DQB1*0302 genotype. In addition, PTPN2 predicted IA whereas INS predicted type 1 diabetes. The final multivariate regression models for both IA and type 1 diabetes included PTPN22, UBASH3A, and INS, in addition to family history of type 1 diabetes and HLA-DR3/4. In general population children, the most frequent combinations including these five significant predictors conferred hazard ratio of up to 13 for IA and >40 for type 1 diabetes. Non-HLA susceptibility alleles may help estimate risk for development of type 1 diabetes in the general population. These findings require replication in different populations.
To define a panel of novel protein biomarkers of renal disease.
RESEARCH DESIGN AND METHODS
Adults with type 1 diabetes in the Coronary Artery Calcification in Type 1 Diabetes study who were initially free of renal complications (n = 465) were followed for development of micro- or macroalbuminuria (MA) and early renal function decline (ERFD, annual decline in estimated glomerular filtration rate of ≥3.3%). The label-free proteomic discovery phase was conducted in 13 patients who progressed to MA by the 6-year visit and 11 control subjects, and four proteins (Tamm-Horsfall glycoprotein, α-1 acid glycoprotein, clusterin, and progranulin) identified in the discovery phase were measured by enzyme-linked immunosorbent assay in 74 subjects: group A, normal renal function (n = 35); group B, ERFD without MA (n = 15); group C, MA without ERFD (n = 16); and group D, both ERFD and MA (n = 8).
In the label-free analysis, a model of progression to MA was built using 252 peptides, yielding an area under the curve (AUC) of 84.7 ± 5.3%. In the validation study, ordinal logistic regression was used to predict development of ERFD, MA, or both. A panel including Tamm-Horsfall glycoprotein (odds ratio 2.9, 95% CI 1.3–6.2, P = 0.008), progranulin (1.9, 0.8–4.5, P = 0.16), clusterin (0.6, 0.3–1.1, P = 0.09), and α-1 acid glycoprotein (1.6, 0.7–3.7, P = 0.27) improved the AUC from 0.841 to 0.889.
A panel of four novel protein biomarkers predicted early renal damage in type 1 diabetes. These findings require further validation in other populations for prediction of renal complications and treatment monitoring.
Infant dietary exposures have been linked to type 1 diabetes (T1D) development. IgG4 antibody responses to food antigens are associated with food intolerances but have not been explored prospectively in the period preceding T1D.
Using a case-cohort design, IgG4 antibodies to ß-lactoglobulin, gluten, and ovalbumin were measured in plasma collected annually from 260 DAISY participants. Of those, 77 developed islet autoimmunity (IA), defined as positive for either insulin, GAD65 or IA-2 autoantibodies on two consecutive visits, and 22 developed T1D.
In mixed model analysis adjusting for HLA-DR status, T1D family history, age and ethnicity, higher ß-lactoglobulin IgG4 concentrations were associated with shorter breastfeeding duration (beta = −0.03, 95% Confidence Interval: −0.05, −0.006) and earlier first cow’s milk exposure (beta = −0.04, 95% Confidence Interval: −0.08, 0.00). Higher gluten IgG4 was associated with older age at gluten introduction (beta = 0.06, 95% Confidence Interval: 0.00, 0.13). In proportional hazards analysis adjusting for HLA-DR status, T1D family history and ethnicity, IgG4 against individual or multiple dietary antigens throughout childhood were not associated with IA. In addition, mean antigen-specific IgG4 concentrations in infancy (age <2 years) were not associated with risk of IA nor progression to T1D. Higher ovalbumin IgG4 at first IA positive visit was marginally associated with progression to T1D (Hazard Ratio: 1.39, 95% Confidence Interval: 1.00, 1.92).
We found no association between the IgG4 response to β-lactoglobulin, gluten, and the development of either IA or T1D. The association between higher ovalbumin and progression to T1D in children with IA should be explored in other populations.
A subset of children develops persistent insulin autoantibodies (IAA; almost always as the only islet autoantibody) without evidence of progression to diabetes. The aim of the current study was the development and characterization of the performance of a nonradioactive fluid phase IAA assay in relation to standard IAA radioassay. We developed a nonradioactive IAA assay where bivalent IAA cross-link two insulin moieties in a fluid phase. The serum samples positive for anti-islet autoantibodies from 150 newly diagnosed patients with diabetes (Barbara Davis Center plus Diabetes Autoantibody Standardization Program [DASP] workshop) and 70 prediabetic subjects who were followed to diabetes were studied. In addition, sequential samples from 64 nondiabetic subjects who were persistently IAA+ were analyzed. With 99th percentile of specificity, the new assay with the technology from Meso Scale Discovery Company (MSD-IAA) detects as positive 61% (61 of 100) of new-onset patients and 80% (56 of 70) of prediabetic patients compared with our current fluid phase micro-IAA radioassay (mIAA; 44 and 74%, respectively). In addition, MSD-IAA demonstrated better sensitivity than our mIAA from blinded DASP workshop (68 vs. 56% with the same 99% specificity). Of 64 IAA+ nondiabetic subjects, 25% (8 of 32) who had only IAA and thus the low risk for progression to diabetes were positive with MSD-IAA assay. In contrast, 100% (32 of 32) high-risk children (IAA plus other islet autoantibodies) were positive with MSD-IAA. The IAA detectable by radioassay, but not MSD-IAA, were usually of lower affinity compared with the IAA of the high-risk children. These data suggest that a subset of IAA with current radioassay (not MSD-IAA) represents biologic false positives in terms of autoimmunity leading to diabetes. We hypothesize that factors related to the mechanism of loss of tolerance leading to diabetes determine high affinity and MSD-IAA reactivity.
The TEDDY study seeks to identify environmental factors influencing the development of type 1 diabetes (T1D) using intensive follow-up of children at elevated genetic risk. The study requires a cost-effective yet accurate screening strategy to identify the high-risk cohort.
The TEDDY cohort was identified through newborn screening using HLA class II genes based on criteria established with pre-TEDDY data. HLA typing was completed at six international centers using different genotyping methods that can achieve >98% accuracy.
TEDDY developed separate inclusion criteria for the general population (GP) and first degree relatives (FDR) of T1D patients. The FDR eligibility includes nine haplogenotypes (DR3/4, DR4/4, DR4/8, DR3/3, DR4/4b, DR4/1, DR4/13, DR4/9 and DR3/9) for broad HLA diversity, while the GP eligibility includes only the first four haplogenotypes with DRB1*0403 as an exclusion allele. TEDDY has screened 414,714 GP infants, of which 19,906 (4.8%) were eligible, while 1,415 of the 6,333 screened FDR infants (22.2%) were eligible. High resolution confirmation testing of the eligible subjects indicated that the low-cost and low-resolution genotyping techniques employed at the screening centers yielded an accuracy of 99%. There were considerable variations in eligibility rates among the centers for GP (3.5% – 7.4%) and FDR (19% – 32%) subjects. The eligibility rates among US ethnic groups were 0.9%, 1.3%, 5.0% and 6.9% for Asians, Black, Caucasians and Hispanics, respectively.
Different low-cost and low-resolution genotyping methods are useful for the efficient and accurate identification of a high-risk cohort for follow-up based on the TEDDY HLA inclusion criteria (ClinicalTrials.gov NCT00279318).
genetic screening; prediction; autoimmunity; type 1 diabetes; population-based
We investigated whether omega-3 fatty acid intake and erythrocyte membrane omega-3 fatty acid levels are associated with conversion to type 1 diabetes in children with islet autoimmunity (IA).
The Diabetes Autoimmunity Study in the Young is following children at increased genetic risk for type 1 diabetes for the development of persistent IA, as defined as being positive for glutamic acid decarboxylase 65, i, or insulin autoantibodies on two consecutive visits, and then for the development of type 1 diabetes, as diagnosed by a physician. One hundred and sixty-seven children with persistent IA were followed for a mean of 4.8 yr, and 45 of these developed type 1 diabetes at a mean age of 8.7 yr. Erythrocyte membrane fatty acids (as a percent of total lipid) and dietary fatty acid intake (estimated via food frequency questionnaire) were analyzed as time-varying covariates in proportional hazards survival analysis, with follow-up time starting at detection of the first autoantibody.
Neither dietary intake of omega-3 fatty acids nor omega-6 fatty acids were associated with conversion to type 1 diabetes, adjusting for human leukocyte antigen (HLA)-DR, family history of type 1 diabetes, age at first IA positivity, maternal age, maternal education, and maternal ethnicity. Adjusting for HLA-DR, family history of type 1 diabetes and age at first IA positivity, omega-3 and omega-6 fatty acid levels of erythrocyte membranes were not associated with conversion to type 1 diabetes.
In this observational study, omega-3 fatty acid intake and status are not associated with conversion to type 1 diabetes in children with IA.
dietary intake; IA; omega-3 fatty acids; type 1 diabetes mellitus
The aim was to examine whether excess weight is associated with coronary artery calcium (CAC), independent of metabolic parameters in adults with type 1 diabetes (T1D).
Subjects between 19 and 56 years of age with T1D (n=621) from the Coronary Artery Calcification in Type 1 Diabetes study were classified as abnormal on four metabolic parameters: blood pressure ≥130/85 mm Hg or on antihypertensive treatment; high-density lipoprotein-cholesterol of <40 mg/dL for men or <50 mg/dL for women; triglycerides of ≥150 mg/dL; or C-reactive protein of ≥3 μg/mL. Study participants with two or more abnormal parameters were classified as metabolically abnormal. Weight categories by body mass index were normal (<25 kg/m2), overweight (25 to <30 kg/m2), and obese (≥30 kg/m2). CAC was measured at two visits 6.0±0.5 years apart. Progression of CAC was defined as an increase in square root transformed CAC volume of ≥2.5 mm3 or development of clinical coronary artery disease.
Among subjects with T1D, 48% of normal, 61% of overweight, and 73% of obese participants were classified as metabolically abnormal (P<0.0001). Overweight and obesity were independently associated with presence of CAC, independent of presence of metabolically abnormal. Obesity but not overweight was associated with CAC progression, independent of the other cardiovascular risk factors.
Although obesity is known to increase cardiovascular disease risk through inducing metabolic abnormalities such as dyslipidemia, hypertension, and inflammation, it is also a strong predictor of subclinical atherosclerosis progression in adults with T1D independent of these factors.
Type I diabetes (T1D) is an autoimmune disease characterized by destruction of insulin-producing β-cells in the pancreas. Although several islet cell autoantigens are known, the breadth and spectrum of autoantibody targets has not been fully explored. Here the luciferase immunoprecipitation systems (LIPS) antibody profiling technology was used to study islet and other organ-specific autoantibody responses in parallel. Examination of an initial cohort of 93 controls and 50 T1D subjects revealed that 16% of the diabetic subjects showed anti-gastric ATPase autoantibodies which did not correlate with autoantibodies against GAD65, IA2, or IA2-β. A more detailed study of a second cohort with 18 potential autoantibody targets revealed marked heterogeneity in autoantibody responses against islet cell autoantigens including two polymorphic variants of ZnT8. A subset of T1D subjects exhibited autoantibodies against several organ-specific targets including gastric ATPase (11%), thyroid peroxidase (14%), and anti-IgA autoantibodies against tissue transglutaminase (12%). Although a few T1D subjects showed autoantibodies against a lung-associated protein KCNRG (6%) and S100-β (8%), no statistically significant autoantibodies were detected against several cytokines. Analysis of the overall autoantibody profiles using a heatmap revealed two major subgroups of approximately similar numbers, consisting of T1D subjects with and without organ-specific autoantibodies. Within the organ-specific subgroup, there was minimal overlap among anti-gastric ATPase, anti-thyroid peroxidase, and anti-transglutaminase seropositivity, and these autoantibodies did not correlate with islet cell autoantibodies. Examination of a third cohort, comprising prospectively collected longitudinal samples from high-risk individuals, revealed that anti-gastric ATPase autoantibodies were present in several individuals prior to detection of islet autoantibodies and before clinical onset of T1D. Taken together, these results suggest that autoantibody portraits derived from islet and organ-specific targets will likely be useful for enhancing the clinical management of T1D.
Glucose effectiveness (SG), the capacity of glucose to enhance its own disposition, is an independent predictor of future diabetes. However, there are data on cross-sectional and longitudinal changes of SG and its components, basal insulin effect on SG (BIE) and SG at zero insulin (GEZI), but the natural course of SG has not been described in a large population.
RESEARCH DESIGN AND METHODS
SG was measured at baseline in 1,265 participants (aged 40–69 years) and at the 5-year examination in 827 participants in the Insulin Resistance Atherosclerosis Study (IRAS) using the frequently sampled intravenous glucose tolerance test. None of these participants were treated with glucose-lowering agents.
In cross-sectional analyses, SG, BIE, and GEZI deteriorated with worsening of glucose tolerance (P < 0.001 for all three associations). In longitudinal analyses among subjects with normal glucose tolerance (NGT) at baseline, SG, BIE, and GEZI declined in those who progressed to impaired glucose tolerance (IGT) or diabetes (P < 0.001 for all three measures). More modest longitudinal changes were demonstrated in individuals with IGT. The transition back to NGT (as opposed to no change) compared with the transition to diabetes was statistically significant for SG (P = 0.049) and BIE (P = 0.042) and was not a statistically significant trend for GEZI (P = 0.332). In individuals with diabetes, only BIE had a significant decline (P = 0.003).
SG, BIE, and GEZI decline in subjects whose glycemic status worsens. SG and GEZI deteriorate more in the initial stages of the disease process.
Herein, we describe recruitment efforts for a trial of lipid-lowering medications in adolescents with type 1 diabetes, age 12–21 years. Based on our experience, future studies will require multiple centers to enroll a sufficient number of participants for adequate data to direct dyslipidemia medication treatment guidelines for adolescents with type 1 diabetes.
Type 1 diabetes; Dyslipidemia; Pediatrics; Lipid-lowering medications
We evaluated predictors of progression to diabetes in children with high-risk HLA genotypes and persistent islet autoantibodies.
RESEARCH DESIGN AND METHODS
The Diabetes Autoimmunity Study in the Young (DAISY) followed 2,542 children with autoantibodies measured to GAD, IA-2, and insulin.
Persistent islet autoantibodies developed in 169 subjects, and 55 of those progressed to diabetes. Children expressing three autoantibodies showed a linear progression to diabetes with 74% cumulative incidence by the 10-year follow-up compared with 70% with two antibodies and 15% with one antibody (P < 0.0001). Both age of appearance of first autoantibody and insulin autoantibody (IAA) levels, but not GAD or IA-2 autoantibodies, were major determinants of the age of diabetes diagnosis (r = 0.79, P < 0.0001).
In the DAISY cohort, 89% of children who progressed to diabetes expressed two or more autoantibodies. Age of diagnosis of diabetes is strongly correlated with age of appearance of first autoantibody and IAA levels.
We sought to define the prevalence of nonislet, organ-specific autoantibodies at diagnosis of type 1 diabetes and to determine the prevalence of comorbid autoimmune diseases.
RESEARCH DESIGN AND METHODS
Children (n = 491) diagnosed with type 1 diabetes at the Barbara Davis Center for Childhood Diabetes were screened for autoimmune thyroid disease (thyroid peroxidase autoantibodies [TPOAb]), celiac disease (tissue transglutaminase autoantibodies [TTGAb]), and Addison disease (21-hydroxylase autoantibodies [21OHAb]).
Of the 491 children, 161 had at least one nonislet autoantibody, and of these, 122 (24.8%) were positive for TPOAb, and 15 of the 122 (12.3%) had autoimmune thyroid disease. There were 57 (11.6%) who were positive for TTGAb, of whom 14 (24.6%) had celiac disease. Five (1.0%) were positive for 21OHAb, of whom one had Addison disease.
Many autoantibody-positive subjects present with additional autoimmune disorders. Detection of these autoantibodies at type 1 diabetes onset may prevent complications associated with delayed diagnosis of these disorders.
Diabetes affects today an estimated 366 million people world-wide, including 20 million to 40 million of patients with type 1 diabetes (T1D). While T1D accounts for 5% to 20% of those with diabetes, it is associated with higher morbidity, mortality and health care cost than the more prevalent type 2 diabetes. Patients with T1D require exogenous insulin for survival and should be identified as soon as possible after diagnosis to avoid high morbidity due to a delay in insulin treatment. It is also important to present to the patient correct prognosis that differs by the type of diabetes. From the research point of view, correct classification should help to identify the etiologies and to develop specific prevention for T1D. This review summarizes evidence that may be helpful in diagnosing T1D in various ethnic groups. Challenges in interpretation of results commonly used to determine the type of diabetes are highlighted.
African diabetes; C-peptide; Diabetes mellitus, type 1; Diagnostic criteria; Ethnic differences; Fulminant diabetes; Genetics; Insulin sensitivity; Islet autoantibodies
Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a lipoprotein-associated enzyme that cleaves oxidized phosphatidylcholines, generating pro-atherosclerotic lysophosphatidylcholine and oxidized free fatty acids. Lp-PLA2 is independently associated with cardiovascular disease (CVD) in a variety of populations. Coronary calcium is a measure of subclinical CVD, and progression of coronary calcification predicts future CVD events. In type 1 diabetes there is an increase in coronary calcium and CVD despite a favorable lipid profile. Levels of Lp-PLA2 in type 1 diabetes are not known, nor is the relationship between Lp-PLA2 and progression of coronary calcification.
The Coronary Artery Calcification in Type 1 Diabetes study measured coronary calcium by electron-beam computed tomography twice over a 2.6 ± 0.3-year interval. Lp-PLA2 mass and activity were measured at baseline (n = 1,097 subjects, 506 with and 591 without type 1 diabetes).
In type 1 diabetes Lp-PLA2 mass was marginally higher (285 ± 79 vs. 278 ± 78 ng/mL, P = 0.1), and Lp-PLA2 activity was significantly lower (137 ± 30 vs. 146 ± 36 nmol/min/mL, P < 0.0001) than in those without diabetes. There was a greater proportion of those with progression of coronary calcification in type 1 diabetes compared with those without diabetes (24% vs. 10%, P < 0.0001). Lp-PLA2 activity was independently associated with progression of coronary calcification in multivariate analysis (4th quartile verses bottom three quartiles, odds ratio = 1.77 [1.08–2.91], P = 0.02). LpPLA2 mass was not significantly associated with progression of coronary calcification in this cohort (P = 0.09).
Lp-PLA2 activity predicts progression of subclinical atherosclerosis in individuals with and without type 1 diabetes.
Does untreated celiac disease associated with type 1 diabetes mellitus worsen microvascular outcomes? Previous studies have concluded that a gluten-free diet offers no major benefit for glycemic control, whereas Leeds and colleagues provide preliminary data to the contrary. The question awaits a long-term prospective study or a clinical trial.
To determine the benefits of screening for celiac autoimmunity via IgA transglutaminase autoantibodies (TG) in children with type 1 diabetes (T1D).
We followed 79 screening-identified TG+ and 56 matched TG− children with T1D for 2 years to evaluate growth, bone mineral density, nutritional status, and diabetes control. TG+ subjects self-selected to gluten-free or gluten-containing diet.
Of the initial cohort, 80% were available for re-examination after 2 years. TG+ subjects had consistently lower weight z-scores and higher urine N-telopeptides than TG− subjects, but similar measures of bone density and diabetes outcomes. TG+ children who remained on a gluten-containing diet had lower IGF-BP3 z-scores compared with TG+ subjects who reported following a gluten-free diet. Children who continued with high TG index throughout the study had lower bone mineral density z-scores, ferritin, and vitamin D 25OH levels, compared with the TG− group.
No significant adverse outcomes were identified in children with T1D with screening-identified TG+ who delay GFD therapy for 2 years. Children with persistently high levels of TG may be at greater risk. The optimal timing of screening and treatment for CD in children with T1D requires further investigation.
type 1 diabetes; pediatric; celiac disease; tissue transglutaminase autoantibodies; screening; gluten; diet
The objective of this study is to examine the relationship among serum levels of 25-hydroxyvitamin D (25[OH]D), polymorphisms in vitamin D-associated genes, and the presence and progression of coronary artery calcification (CAC) in adults with type 1 diabetes.
RESEARCH DESIGN AND METHODS
This prospective study included 374 non-Hispanic white individuals with type 1 diabetes (mean age 40 ± 9 years; 46% were male). CAC was measured at the baseline and 3- and 6-year follow-up visits were determined by electron beam computed tomography. Serum 25[OH]D levels were measured by liquid chromatography tandem mass spectrometry at the 3-year visit.
Normal (>30 ng/mL), insufficient (20–30 ng/mL), and deficient (<20 ng/mL) 25-[OH]D levels were present in 65%, 25%, and 10% of the individuals with type 1 diabetes, respectively. 25[OH]D deficiency was associated with the presence of CAC at the 3-year visit, odds ratio (OR) = 3.3 (95% CI 1.6–7.0), adjusting for age, sex, and hours of daylight. In subjects free of CAC at the 3-year visit, 25[OH]D deficiency predicted the development of CAC over the next 3 years in those with the vitamin D receptor M1T CC genotype (OR = 6.5 [1.1–40.2], P = 0.04) than in those with the CT or TT genotype (OR = 1.6 [0.3–8.6], P = 0.57).
Vitamin D deficiency independently predicts prevalence and development of CAC, a marker of coronary artery plaque burden, in individuals with type 1 diabetes.
To assess insulin action on peripheral glucose utilization and nonesterified fatty acid (NEFA) suppression as a predictor of coronary artery calcification (CAC) in patients with type 1 diabetes and nondiabetic controls.
RESEARCH DESIGN AND METHODS
Insulin action was measured by a three-stage hyperinsulinemic-euglycemic clamp (4, 8, and 40 mU/m2/min) in 87 subjects from the Coronary Artery Calcification in Type 1 Diabetes cohort (40 diabetic, 47 nondiabetic; mean age 45 ± 8 years; 55% female).
Peripheral glucose utilization was lower in subjects with type 1 diabetes compared with nondiabetic controls: glucose infusion rate (mg/kg FFM/min) = 6.19 ± 0.72 vs. 12.71 ± 0.66, mean ± SE, P < 0.0001, after adjustment for age, sex, BMI, fasting glucose, and final clamp glucose and insulin. Insulin-induced NEFA suppression was also lower in type 1 diabetic compared with nondiabetic subjects: NEFA levels (μM) during 8 mU/m2/min insulin infusion = 370 ± 27 vs. 185 ± 25, P < 0.0001, after adjustment for age, sex, BMI, fasting glucose, and time point insulin. Lower glucose utilization and higher NEFA levels, correlated with CAC volume (r = −0.42, P < 0.0001 and r = 0.41, P < 0.0001, respectively) and predicted the presence of CAC (odds ratio [OR] = 0.45, 95% CI = 0.22–0.93, P = 0.03; OR = 2.4, 95% CI = 1.08–5.32, P = 0.032, respectively). Insulin resistance did not correlate with GHb or continuous glucose monitoring parameters.
Type 1 diabetic patients are insulin resistant compared with nondiabetic subjects, and the degree of resistance is not related to current glycemic control. Insulin resistance predicts the extent of coronary artery calcification and may contribute to the increased risk of cardiovascular disease in patients with type 1 diabetes as well as subjects without diabetes.
To investigate whether enterovirus infections predict progression to type 1 diabetes in genetically predisposed children repeatedly positive for islet autoantibodies.
RESEARCH DESIGN AND METHODS
Since 1993, the Diabetes and Autoimmunity Study in the Young (DAISY) has followed 2,365 genetically predisposed children for islet autoimmunity and type 1 diabetes. Venous blood and rectal swabs were collected every 3–6 months after seroconversion for islet autoantibodies (against GAD, insulin, or insulinoma-associated antigen-2 [IA-2]) until diagnosis of diabetes. Enteroviral RNA in serum or rectal swabs was detected using reverse transcriptase PCR with primers specific for the conserved 5′ noncoding region, detecting essentially all enterovirus serotypes.
Of 140 children who seroconverted to repeated positivity for islet autoantibodies at a median age of 4.0 years, 50 progressed to type 1 diabetes during a median follow-up of 4.2 years. The risk of progression to clinical type 1 diabetes in the sample interval following detection of enteroviral RNA in serum (three diabetes cases diagnosed among 17 intervals) was significantly increased compared with that in intervals following a negative serum enteroviral RNA test (33 cases diagnosed among 1,064 intervals; hazard ratio 7.02 [95% CI 1.95–25.3] after adjusting for number of autoantibodies). Results remained significant after adjustment for ZnT8-autoantibodies and after restriction to various subgroups. Enteroviral RNA in rectal swabs was not predictive of progression to type 1 diabetes. No evidence for viral persistence was found.
This novel observation suggests that progression from islet autoimmunity to type 1 diabetes may increase after an enterovirus infection characterized by the presence of viral RNA in blood.