From Antiquity to Modern Times: A History of Diabetes Mellitus and Its Treatments.

The past 200 years have brought an understanding of diabetes and its pathogenesis, as well as the development of treatments that could not have been predicted when the disorder was first clinically described 2000 years ago. Beginning in the late 19th century, the initial descriptions of the microscopic anatomy of the pancreatic islets by Langerhans led to recognition of pancreatic endocrine function. Many investigators attempted to isolate the hypoglycemic factor produced by the pancreas, but Banting, Best, Macleod, and Collip were able to extract and purify "isletin" to treat human diabetes in 1921. Rapid scientific progress over the next 100 years led to an understanding of insulin synthesis, structure and function, production of modified synthetic insulins, and the physiopathology that permitted classification of diabetes subtypes. Improvements in control of diabetes have reduced the risks of complications. In less than two hundred years, we have gone from being unable to measure glucose in blood to being able to offer people with diabetes continuous blood glucose monitoring, linked to continuous subcutaneous insulin infusion. We come ever closer with new drugs and treatments to repair the biochemical defects in type 2 diabetes and to biologically replace islets and their function in type 1 diabetes. This review addresses the history of continuing progress in diabetes care.

Increasing plasma glucose before the development of type 1 diabetes-the TRIGR study.

OBJECTIVE: The ß-cell stress hypothesis suggests that increased insulin demand contributes to the development of type 1 diabetes. In the TRIGR trial we set out to assess the profile of plasma glucose and HbA1c before the diagnosis of clinical diabetes compared to nondiabetic children. RESEARCH DESIGN AND METHODS: A cohort of children (N = 2159) with an affected first-degree relative and increased HLA risk were recruited 2002-2007 and followed until 2017. To study the relationship between plasma glucose/HbA1c and the development of autoantibodies or clinical disease Kaplan-Meir curves were developed. Mixed models were constructed for plasma glucose and HbA1c separately. RESULTS: A family history of type 2 diabetes was related to an increase in plasma glucose (p < 0.001). An increase in glucose from the previous sample predicted clinical diabetes (p < 0.001) but not autoantibodies. An increase of HbA1c of 20% or 30% from the previous sample predicted the development of any autoantibody (p < 0.003 resp <0.001) and the development of diabetes (p < 0.002 resp <0.001. Participants without autoantibodies had lower HbA1c (mean 5.18%, STD 0.24; mean 33.08 mmol/mol, STD 2.85) than those who progressed to clinical disease (5.31%, 0.42; 34.46 mmol/mol, 4.68; p < 0.001) but higher than those who developed any autoantibody (5.10%, 0.30; 32.21 mmol/mol, 3.49; p < 0.001), or multiple autoantibodies (5.11%, 0.35; 32.26 mmol/mol, 3.92; p < 0.003). CONCLUSIONS: A pronounced increase in plasma glucose and HbA1c precedes development of clinical diabetes, while the association between plasma glucose or HbA1c and development of autoantibodies is complex. Increased insulin demand may contribute to development of type 1 diabetes.

Dietary compliance in a randomized double-blind infant feeding trial during infancy aiming at prevention of type 1 diabetes.

The international Trial to Reduce IDDM in the Genetically at Risk (TRIGR) tested the hypothesis whether extensively hydrolyzed casein-based versus regular cow's milk-based infant formula reduces the risk of type 1 diabetes. We describe dietary compliance in the trial in terms of study formula intake, feeding of nonrecommended foods, and serum cow's milk antibody concentration reflecting intake of cow's milk protein among 2,159 eligible newborn infants with a biological first-degree relative affected by type 1 diabetes and with HLA-conferred susceptibility to type 1 diabetes. The participating infants were introduced to the study formula feeding at the median age of 15 days with a median duration of study formula use of 63 days. During the intervention, 80% of the infants received study formula. Of these, 57% received study formula for at least 2 months. On average, 45.5 l of study formula were used per infant. Only 13% of the population had received a nonrecommended food by the age of 6 months. The dietary compliance was similar in the intervention and control arm. The reported cow's milk consumption by the families matched very well with measured serum casein IgA and IgG antibody concentration. To conclude, good compliance was observed in this randomized infant feeding trial. Compliance varied between the regions and those infants who were breastfed for a longer period of time had a shorter exposure to the study formula. High dietary compliance in infant feeding trial is necessary to allow accurate interpretation of study results.

Nutrition and Obesity in the Pathogenesis of Youth-Onset Type 1 Diabetes and Its Complications.

Since the 1980s, there has been a dramatic rise in the prevalence of overweight and obesity in pediatric populations, in large part driven by sedentary lifestyles and changing dietary patterns with more processed foods. In parallel with the rise in pediatric obesity in the general population, the prevalence of overweight and obesity has increased among children and adolescents with type 1 diabetes. Adiposity has been implicated in a variety of mechanisms both potentiating the risk for type 1 diabetes as well as exacerbating long-term complications, particularly cardiovascular disease. Treatment options targeting the unique needs of obese pediatric patients, both before and after diagnosis of type 1 diabetes, are limited. In this review, we discuss the history of the epidemiology of the obesity epidemic in the context of pediatric type 1 diabetes, highlight the possible role of obesity in type 1 diabetes pathogenesis and review the concept of "double diabetes". The impact of obesity at and after diagnosis will be discussed, including noted differences in clinical and biochemical markers, lipid abnormalities, and long-term cardiovascular complications. Finally, we will review the existing literature on pharmacologic and nutritional interventions as potential treatment strategies for youth with coexisting type 1 diabetes and obesity.

Growth and development of islet autoimmunity and type 1 diabetes in children genetically at risk.

AIMS/HYPOTHESIS: We aimed to evaluate the relationship between childhood growth measures and risk of developing islet autoimmunity (IA) and type 1 diabetes in children with an affected first-degree relative and increased HLA-conferred risk. We hypothesised that being overweight or obese during childhood is associated with a greater risk of IA and type 1 diabetes. METHODS: Participants in a randomised infant feeding trial (N = 2149) were measured at 12 month intervals for weight and length/height and followed for IA (at least one positive out of insulin autoantibodies, islet antigen-2 autoantibody, GAD autoantibody and zinc transporter 8 autoantibody) and development of type 1 diabetes from birth to 10-14 years. In this secondary analysis, Cox proportional hazard regression models were adjusted for birthweight and length z score, sex, HLA risk, maternal type 1 diabetes, mode of delivery and breastfeeding duration, and stratified by residence region (Australia, Canada, Northern Europe, Southern Europe, Central Europe and the USA). Longitudinal exposures were studied both by time-varying Cox proportional hazard regression and by joint modelling. Multiple testing was considered using family-wise error rate at 0.05. RESULTS: In the Trial to Reduce IDDM in the Genetically at Risk (TRIGR) population, 305 (14.2%) developed IA and 172 (8%) developed type 1 diabetes. The proportions of children overweight (including obese) and obese only were 28% and 9% at 10 years, respectively. Annual growth measures were not associated with IA, but being overweight at 2-10 years of life was associated with a twofold increase in the development of type 1 diabetes (HR 2.39; 95% CI 1.46, 3.92; p < 0.001 in time-varying Cox regression), and similarly with joint modelling. CONCLUSIONS/INTERPRETATION: In children at genetic risk of type 1 diabetes, being overweight at 2-10 years of age is associated with increased risk of progression from multiple IA to type 1 diabetes and with development of type 1 diabetes, but not with development of IA. Future studies should assess the impact of weight management strategies on these outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT00179777.

Association between family history, early growth and the risk of beta cell autoimmunity in children at risk for type 1 diabetes.

AIMS/HYPOTHESIS: The aim of this work was to examine the relationship between family history of type 1 diabetes, birthweight, growth during the first 2 years and development of multiple beta cell autoantibodies in children with a first-degree relative with type 1 diabetes and HLA-conferred disease susceptibility. METHODS: In a secondary analysis of the Trial to Reduce IDDM in the Genetically at Risk (TRIGR), clinical characteristics and development of beta cell autoantibodies were compared in relation to family history of type 1 diabetes (mother vs father vs sibling) in 2074 children from families with a single affected family member. RESULTS: Multiple autoantibodies (≥2 of 5 measured) developed in 277 (13%) children: 107 (10%), 114 (16%) and 56 (18%) born with a mother, father or sibling with type 1 diabetes, respectively (p < 0.001). The HR for time to multiple autoimmunity was 0.54 (95% CI 0.39, 0.75) in offspring of affected mothers (n = 107/1046, p < 0.001) and 0.81 (95% CI 0.59, 1.11) (n = 114/722, p = 0.19) in offspring of affected fathers, compared with participants with a sibling with type 1 diabetes (comparator group n = 56/306). The time to the first autoantibody present (to insulin, GAD, tyrosine phosphatase-related insulinoma-associated 2 molecules, islet cell or zinc transporter 8) was similar in the three groups. Height velocity (z score/year) in the first 24 months was independently associated with developing multiple antibodies in the total cohort (HR 1.31 [95% CI 1.01, 1.70], p = 0.04). A higher birthweight in children born to an affected mother vs affected father or an affected sibling was not related to the risk of multiple autoimmunity. CONCLUSIONS/INTERPRETATION: The risk of developing multiple autoantibodies was lower in children with maternal type 1 diabetes. For the whole group, this risk of developing multiple autoantibodies was independent of birthweight but was greater in those with increased height velocity during the first 2 years of life. However, the risk associated with paternal type 1 diabetes was not linked to differences in birthweight or early growth. TRIAL REGISTRATION: ClinicalTrials.gov NCT00179777 Graphical abstract.

The Pathological Evolution of Glucose Response Curves During the Progression to Type 1 Diabetes in the TrialNet Pathway to Prevention Study.

OBJECTIVE: Glucose response curves (GRCs) during oral glucose tolerance tests (OGTTs) are predictive of type 1 diabetes. We performed a longitudinal analysis in pancreatic autoantibody-positive individuals to assess 1) characteristic GRC changes during progression to type 1 diabetes and 2) GRC changes in relation to ß-cell function changes and to combined glucose and C-peptide response curve (GCRC) changes. RESEARCH DESIGN AND METHODS: Among antibody-positive individuals with serial OGTTs in the TrialNet Pathway to Prevention study, GRC changes from first to last OGTTs were compared between progressors (n = 298) to type 1 diabetes and nonprogressors (n = 2,216). GRC changes from last OGTT before diagnosis to diagnostic OGTTs were studied in progressors. RESULTS: GRCs changed more frequently from biphasic (two peaks) to monophasic (one peak) GRCs between first and last OGTTs in progressors than in nonprogressors (75.4% vs. 51.0%, respectively; P < 0.001). In contrast, GRCs of progressors changed less frequently from monophasic to biphasic than those of nonprogressors (12.6% vs. 30.6%; P < 0.001). Monotonic (continuous increase) GRCs were present in 47.7% of progressors at diagnosis. The early (30-0 min) C-peptide response decreased in progressors with GRCs changing from biphasic to monophasic between first and last OGTTs (P < 0.001) and from monophasic to monotonic between last and diagnostic OGTTs (P < 0.001). Conversely, the early C-peptide response increased among nonprogressors with GRCs changing from monophasic to biphasic (P < 0.001). Changes in GRCs were related to changes in GCRCs. CONCLUSIONS: Characteristic GRC changes, biphasic to monophasic to monotonic, occur during the progression to type 1 diabetes. These GRC changes correspond to decreasing ß-cell function.

Early and late C-peptide responses during oral glucose tolerance testing are oppositely predictive of type 1 diabetes in autoantibody-positive individuals.

We examined whether the timing of the C-peptide response during an oral glucose tolerance test (OGTT) in relatives of patients with type 1 diabetes (T1D) is predictive of disease onset. We examined baseline 2-h OGTTs from 670 relatives participating in the Diabetes Prevention Trial-Type 1 (age: 13.8 ± 9.6 years; body mass index z-score: 0.3 ± 1.1; 56% male) using univariate regression models. T1D risk increased with lower early C-peptide responses (30-0 min) (χ2 = 28.8, P < 0.001), and higher late C-peptide responses (120-60 min) (χ2 = 23.3, P < 0.001). When both responses were included in a proportional hazards model, they remained independently and oppositely associated with T1D, with a stronger overall association for the combined model than either response alone (χ2 = 41.1; P < 0.001). Using receiver operating characteristic curve analysis, the combined early and late C-peptide response was more accurately predictive of T1D than area under the curve C-peptide (P = 0.005). Our findings demonstrate that lower early and higher late C-peptide responses serve as indicators of increased T1D risk.

Excess BMI Accelerates Islet Autoimmunity in Older Children and Adolescents.

OBJECTIVE: Sustained excess BMI increases the risk of type 1 diabetes (T1D) in autoantibody-positive relatives without diabetes of patients. We tested whether elevated BMI also accelerates the progression of islet autoimmunity before T1D diagnosis. RESEARCH DESIGN AND METHODS: We studied 706 single autoantibody-positive pediatric TrialNet participants (ages 1.6-18.6 years at baseline). Cumulative excess BMI (ceBMI) was calculated for each participant based on longitudinally accumulated BMI ≥85th age- and sex-adjusted percentile. Recursive partitioning analysis and multivariable modeling defined the age cut point differentiating the risk for progression to multiple positive autoantibodies. RESULTS: At baseline, 175 children (25%) had a BMI ≥85th percentile. ceBMI range was -9.2 to 15.6 kg/m2 (median -1.91), with ceBMI ≥0 kg/m2 corresponding to persistently elevated BMI ≥85th percentile. Younger age increased the progression to multiple autoantibodies, with age cutoff of 9 years defined by recursive partitioning analysis. Although ceBMI was not significantly associated with progression from single to multiple autoantibodies overall, there was an interaction with ceBMI ≥0 kg/m2, age, and HLA (P = 0.009). Among children ≥9 years old without HLA DR3-DQ2 and DR4-DQ8, ceBMI ≥0 kg/m2 increased the rate of progression from single to multiple positive autoantibodies (hazard ratio 7.32, P = 0.004) and conferred a risk similar to that in those with T1D-associated HLA haplotypes. In participants <9 years old, the effect of ceBMI on progression to multiple autoantibodies was not significant regardless of HLA type. CONCLUSIONS: These data support that elevated BMI may exacerbate islet autoimmunity prior to clinical T1D, particularly in children with lower risk based on age and HLA. Interventions to maintain normal BMI may prevent or delay the progression of islet autoimmunity.

Persistent C-peptide levels and microvascular complications in childhood onset type 1 diabetes of long duration.

AIMS: The aim was to determine if persistent c-peptide in long duration childhood onset (<17 years) type 1 diabetes (T1D) related to microvascular complications. METHODS: Pittsburgh Epidemiology of Diabetes Complications (EDC) participants (n = 185) had serum c-peptide levels measured by Mercodia ultra-sensitive ELISA at the 25-year follow-up exam. Microvascular complications between those with and without detectable c-peptide were compared. RESULTS: Eighteen (9.7%) participants had detectable median c-peptide levels of 3.8 (2.6, 12.2) pmol/L and did not differ from those without detectable levels. No differences in microalbuminuria, confirmed distal symmetric polyneuropathy, renal failure, or between those with one or more complications were found between the two groups. Proliferative retinopathy (PR) was marginally lower in those with detectable c-peptide (33.3% vs 55.1%, p = 0.08). However, those with c-peptide were somewhat less likely to have fasted for a full 8-h (66.7% vs. 84.9%, p = 0.09). Excluding those not fully fasted, PR no longer approached significance but macroalbuminuria became marginally lower in those with detectable levels (23.4% vs 0%, p = 0.07). CONCLUSIONS: Low levels of c-peptide in T1D patients of long duration were detected but were not strongly related to microvascular complications.

Autoantibodies Directed Toward a Novel IA-2 Variant Protein Enhance Prediction of Type 1 Diabetes.

We identified autoantibodies (AAb) reacting with a variant IA-2 molecule (IA-2var) that has three amino acid substitutions (Cys27, Gly608, and Pro671) within the full-length molecule. We examined IA-2var AAb in first-degree relatives of type 1 diabetes (T1D) probands from the TrialNet Pathway to Prevention Study. The presence of IA-2var-specific AAb in relatives was associated with accelerated progression to T1D in those positive for AAb to GAD65 and/or insulin but negative in the standard test for IA-2 AAb. Furthermore, relatives with single islet AAb (by traditional assays) and carrying both IA-2var AAb and the high-risk HLA-DRB1*04-DQB1*03:02 haplotype progress rapidly to onset of T1D. Molecular modeling of IA-2var predicts that the genomic variation that alters the three amino acids induces changes in the three-dimensional structure of the molecule, which may lead to epitope unmasking in the IA-2 extracellular domain. Our observations suggest that the presence of AAb to IA-2var would identify high-risk subjects who would benefit from participation in prevention trials who have one islet antibody by traditional testing and otherwise would be misclassified as "low risk" relatives.

Low-Dose Anti-Thymocyte Globulin Preserves C-Peptide, Reduces HbA1c, and Increases Regulatory to Conventional T-Cell Ratios in New-Onset Type 1 Diabetes: Two-Year Clinical Trial Data.

A three-arm, randomized, double-masked, placebo-controlled phase 2b trial performed by the Type 1 Diabetes TrialNet Study Group previously demonstrated that low-dose anti-thymocyte globulin (ATG) (2.5 mg/kg) preserved ß-cell function and reduced HbA1c for 1 year in new-onset type 1 diabetes. Subjects (N = 89) were randomized to 1) ATG and pegylated granulocyte colony-stimulating factor (GCSF), 2) ATG alone, or 3) placebo. Herein, we report 2-year area under the curve (AUC) C-peptide and HbA1c, prespecified secondary end points, and potential immunologic correlates. The 2-year mean mixed-meal tolerance test-stimulated AUC C-peptide, analyzed by ANCOVA adjusting for baseline C-peptide, age, and sex (n = 82) with significance defined as one-sided P < 0.025, was significantly higher in subjects treated with ATG versus placebo (P = 0.00005) but not ATG/GCSF versus placebo (P = 0.032). HbA1c was significantly reduced at 2 years in subjects treated with ATG (P = 0.011) and ATG/GCSF (P = 0.022) versus placebo. Flow cytometry analyses demonstrated reduced circulating CD4:CD8 ratio, increased regulatory T-cell:conventional CD4 T-cell ratios, and increased PD-1+CD4+ T cells following low-dose ATG and ATG/GCSF. Low-dose ATG partially preserved ß-cell function and reduced HbA1c 2 years after therapy in new-onset type 1 diabetes. Future studies should determine whether low-dose ATG might prevent or delay the onset of type 1 diabetes.

Associations of HbA1c with the timing of C-peptide responses during the oral glucose tolerance test at the diagnosis of type 1 diabetes.

BACKGROUND: In new onset type 1 diabetes (T1D), overall C-peptide measures such as area under the curve (AUC) C-peptide and peak C-peptide are useful for estimating the extent of ß-cell dysfunction, and for assessing responses to intervention therapy. However, measures of the timing of C-peptide responsiveness could have additional value. OBJECTIVES: We assessed the contribution of the timing of C-peptide responsiveness during oral glucose tolerance tests (OGTTs) to hemoglobin A1c (HbA1c) variation at T1D diagnosis. METHODS: We analyzed data from 85 individuals <18 years with OGTTs and HbA1c measurements at diagnosis. Overall [AUC and peak C-peptide] and timing measures [30-0 minute C-peptide (early); 60 to 120 minute C-peptide sum-30 minutes (late); 120/30 C-peptide; time to peak C-peptide] were utilized. RESULTS: At diagnosis, the mean (±SD) age was 11.2 ± 3.3 years, body mass index (BMI)-z was 0.4 ± 1.1, 51.0% were male. The average HbA1c was 43.54 ± 8.46 mmol/mol (6.1 ± 0.8%). HbA1c correlated inversely with the AUC C-peptide (P < 0.001), peak C-peptide (P < 0.001), early and late C-peptide responses (P < 0.001 each), and 120/30 C-peptide (P < 0.001). Those with a peak C-peptide occurring at ≤60 minutes had higher HbA1c values than those with peaks later (P = 0.003). HbA1c variance was better explained with timing measures added to regression models (R2 = 11.6% with AUC C-peptide alone; R2 = 20.0% with 120/30 C-peptide added; R2 = 13.7% with peak C-peptide alone, R2 = 20.4% with timing of the peak added). Similar associations were seen between the 2-hour glucose and the C-peptide measures. CONCLUSIONS: These findings show that the addition of timing measures of C-peptide responsiveness better explains HbA1c variation at diagnosis than standard measures alone.

Celiac Autoimmunity Is Associated With Lower Blood Pressure and Renal Risk in Type 1 Diabetes.

Context: Though the long-term consequences of celiac disease (CD) in type 1 diabetes are unclear, CD has been associated with increased prevalence of end-stage renal disease (ESRD) independent of type 1 diabetes. Objective: We evaluated whether celiac autoimmunity is related to the cumulative incidence of microalbuminuria [albumin excretion rate (AER) 20 to 200 µg/min], macroalbuminuria (AER >200 µg/min), and ESRD. Design, Patients, and Methods: In the prospective follow-up of the Pittsburgh Epidemiology of Diabetes Complications study of childhood-onset type 1 diabetes, 618 participants were screened for tissue transglutaminase (tTG) antibodies with a clinical assay. Nephropathy outcomes were determined at 25 years of diabetes duration. Results: Overall, the 33 subjects (5.3%) with strongly positive tTG levels (≥3 times the upper limit of normal) or a reported clinical history of CD had lower baseline blood pressure and lipid values. At 25 years of diabetes duration, a lower cumulative incidence of macroalbuminuria in strongly positive subjects compared with those with negative serology (3.6% vs 30.0%; P = 0.003) remained significant after adjustment for age, HbA1c, lipid measures, and blood pressure (adjusted P = 0.004). No considerable differences between these subjects and tTG-negative groups were found for microalbuminuria (40.0% vs 57.1%) or ESRD (0 vs 4.1%). Conclusions: These findings show that strongly positive celiac autoimmunity status in individuals with childhood-onset type 1 diabetes is associated with lower baseline blood pressure and cholesterol measurements as well as lower macroalbuminuria risk after 25 years of type 1 diabetes duration with no increase in the risk of microalbuminuria or ESRD.

Low-Dose Anti-Thymocyte Globulin (ATG) Preserves ß-Cell Function and Improves HbA1c in New-Onset Type 1 Diabetes.

OBJECTIVE: A pilot study suggested that combination therapy with low-dose anti-thymocyte globulin (ATG) and pegylated granulocyte colony-stimulating factor (GCSF) preserves C-peptide in established type 1 diabetes (T1D) (duration 4 months to 2 years). We hypothesized that 1) low-dose ATG/GCSF or 2) low-dose ATG alone would slow the decline of ß-cell function in patients with new-onset T1D (duration <100 days). RESEARCH DESIGN AND METHODS: A three-arm, randomized, double-masked, placebo-controlled trial was performed by the Type 1 Diabetes TrialNet Study Group in 89 subjects: 29 subjects randomized to ATG (2.5 mg/kg intravenously) followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for 6 doses), 29 to ATG alone (2.5 mg/kg), and 31 to placebo. The primary end point was mean area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test 1 year after initiation of therapy. Significance was defined as one-sided P value < 0.025. RESULTS: The 1-year mean AUC C-peptide was significantly higher in subjects treated with ATG (0.646 nmol/L) versus placebo (0.406 nmol/L) (P = 0.0003) but not in those treated with ATG/GCSF (0.528 nmol/L) versus placebo (P = 0.031). HbA1c was significantly reduced at 1 year in subjects treated with ATG and ATG/GCSF, P = 0.002 and 0.011, respectively. CONCLUSIONS: Low-dose ATG slowed decline of C-peptide and reduced HbA1c in new-onset T1D. Addition of GCSF did not enhance C-peptide preservation afforded by low-dose ATG. Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of the disease.

Characteristics of slow progression to diabetes in multiple islet autoantibody-positive individuals from five longitudinal cohorts: the SNAIL study.

AIMS/HYPOTHESIS: Multiple islet autoimmunity increases risk of diabetes, but not all individuals positive for two or more islet autoantibodies progress to disease within a decade. Major islet autoantibodies recognise insulin (IAA), GAD (GADA), islet antigen-2 (IA-2A) and zinc transporter 8 (ZnT8A). Here we describe the baseline characteristics of a unique cohort of 'slow progressors' (n = 132) who were positive for multiple islet autoantibodies (IAA, GADA, IA-2A or ZnT8A) but did not progress to diabetes within 10 years. METHODS: Individuals were identified from five studies (BABYDIAB, Germany; Diabetes Autoimmunity Study in the Young [DAISY], USA; All Babies in Southeast Sweden [ABIS], Sweden; Bart's Oxford Family Study [BOX], UK and the Pittsburgh Family Study, USA). Multiple islet autoantibody characteristics were determined using harmonised assays where possible. HLA class II risk was compared between slow progressors and rapid progressors (n = 348 diagnosed <5 years old from BOX) using the χ2 test. RESULTS: In the first available samples with detectable multiple antibodies, the most frequent autoantibodies were GADA (92%), followed by ZnT8A (62%), IAA (59%) and IA-2A (41%). High risk HLA class II genotypes were less frequent in slow (28%) than rapid progressors (42%, p = 0.011), but only two slow progressors carried the protective HLA DQ6 allele. CONCLUSION: No distinguishing characteristics of slow progressors at first detection of multiple antibodies have yet been identified. Continued investigation of these individuals may provide insights into slow progression that will inform future efforts to slow or prevent progression to clinical diabetes.

The shape of the glucose concentration curve during an oral glucose tolerance test predicts risk for type 1 diabetes.

AIMS/HYPOTHESIS: We aimed to examine: (1) whether specific glucose-response curve shapes during OGTTs are predictive of type 1 diabetes development; and (2) the extent to which the glucose-response curve is influenced by insulin secretion. METHODS: Autoantibody-positive relatives of people with type 1 diabetes whose baseline OGTT met the definition of a monophasic or biphasic glucose-response curve were followed for the development of type 1 diabetes (n = 2627). A monophasic curve was defined as an increase in OGTT glucose between 30 and 90 min followed by a decline of ≥ 0.25 mmol/l between 90 and 120 min. A biphasic response curve was defined as a decrease in glucose after an initial increase, followed by a second increase of ≥ 0.25 mmol/l. Associations of type 1 diabetes risk with glucose curve shapes were examined using cumulative incidence curve comparisons and proportional hazards regression. C-peptide responses were compared with and without adjustments for potential confounders. RESULTS: The majority of participants had a monophasic curve at baseline (n = 1732 [66%] vs n = 895 [34%]). The biphasic group had a lower cumulative incidence of type 1 diabetes (p < 0.001), which persisted after adjustments for age, sex, BMI z score and number of autoantibodies (p < 0.001). Among the monophasic group, the risk of type 1 diabetes was greater for those with a glucose peak at 90 min than for those with a peak at 30 min; the difference persisted after adjustments (p < 0.001). Compared with the biphasic group, the monophasic group had a lower early C-peptide (30-0 min) response, a lower C-peptide index (30-0 min C-peptide/30-0 min glucose), as well as a greater 2 h C-peptide level (p < 0.001 for all). CONCLUSIONS/INTERPRETATION: Those with biphasic glucose curves have a lower risk of progression to type 1 diabetes than those with monophasic curves, and the risk among the monophasic group is increased when the glucose peak occurs at 90 min than at 30 min. Differences in glucose curve shapes between the monophasic and biphasic groups appear to be related to C-peptide responses.

The Role of Age and Excess Body Mass Index in Progression to Type 1 Diabetes in At-Risk Adults.

Background: Given the global rise in both type 1 diabetes incidence and obesity, the role of body mass index (BMI) on type 1 diabetes pathophysiology has gained great interest. Sustained excess BMI in pediatric participants of the TrialNet Pathway to Prevention (PTP) cohort increased risk for progression to type 1 diabetes, but the effects of age and obesity in adults remain largely unknown. Objective: To determine the effect of age and sustained obesity on the risk for type 1 diabetes in adult participants in the TrialNet PTP cohort (i.e., nondiabetic autoantibody-positive relatives of patients with type 1 diabetes). Research Design and Methods: Longitudinally accumulated BMI >25 kg/m2 was calculated to generate a cumulative excess BMI (ceBMI) for each participant, with ceBMI values ≥0 kg/m2 and ≥5 kg/m2 representing sustained overweight or obese status, respectively. Recursive partitioning analysis yielded sex- and age-specific thresholds for ceBMI that confer the greatest risk for type 1 diabetes progression. Results: In this cohort of 665 adults (age 20 to 50 years; median follow-up, 3.9 years), 49 participants developed type 1 diabetes. Age was an independent protective factor for type 1 diabetes progression (hazard ratio, 0.95; P = 0.008), with a threshold of >35 years that reduced risk for type 1 diabetes. In men age >35 years and women age <35 years, sustained obesity (ceBMI ≥5 kg/m2) increased the risk for type 1 diabetes. Conclusions: Age is an important factor for type 1 diabetes progression in adults and influences the impact of elevated BMI, indicating an interplay of excess weight, age, and sex in adult type 1 diabetes pathophysiology.

Impact of Age and Antibody Type on Progression From Single to Multiple Autoantibodies in Type 1 Diabetes Relatives.

Context: Islet autoantibodies are markers of type 1 diabetes, and an increase in number of autoantibodies detected during the preclinical phase predicts progression to overt disease. Objective: To refine the effect of age in relation to islet antibody type on progression from single to multiple autoantibodies in relatives of people with type 1 diabetes. Research Design and Methods: We examined 994 relatives with normal glucose tolerance who were positive for a single autoantibody, followed prospectively in the TrialNet Pathway to Prevention. Antibodies to glutamic acid decarboxylase (GADA), insulin (IAA), insulinoma-associated antigen 2, and zinc transporter 8 and islet cell antibodies were tested every 6 to 12 months. The primary outcome was confirmed development of multiple autoantibodies. Age was categorized as <8 years, 8 to 11 years, 12 to 17 years, and ≥18 years, and optimal age breakpoints were identified by recursive partitioning analysis. Results: After median follow-up of 2 years, 141 relatives had developed at least one additional autoantibodies. Five-year risk was inversely related to age, but the pattern differed by antibody type: Relatives with GADA showed a gradual decrease in risk over the four age groups, whereas relatives with IAA showed a sharp decrease above age 8 years. Recursive partitioning analysis identified age breakpoints at 14 years in relatives with GADA and at 4 years in relatives with IAA. Conclusions: In relatives with IAA, spread of islet autoimmunity is largely limited to early childhood, whereas immune responses initially directed at glutamic acid decarboxylase can mature over a longer period. These differences have important implications for monitoring these patients and for designing prevention trials.