Prediction of impending type 1 diabetes through automated dual-label measurement of proinsulin:C-peptide ratio

Background : The hyperglycemic clamp test, the gold standard of beta cell function, predicts impending type 1 diabetes in islet autoantibody-positive individuals, but the latter may benefit from less invasive function tests such as the proinsulin: C-peptide ratio (PI:C). The present study aims to optimize precision of PI:C measurements by automating a dual-label trefoil-type time-resolved fluorescence immunoassay (TT-TRFIA), and to compare its diagnostic performance for predicting type 1 diabetes with that of clamp-derived C-peptide release. Methods : Between-day imprecision (n = 20) and split-sample analysis (n = 95) were used to compare TT-TRFIA (Auto Delfia, Perkin-Elmer) with separate methods for proinsulin (in-house TRFIA) and C-peptide (Elecsys, Roche). High-risk multiple autoantibody-positive firstdegree relatives (n = 49; age 5-39) were tested for fasting PI:C, HOMA2-IR and hyperglycemic clamp and followed for 20-57 months (interquartile range). Results : TT-TRFIA values for proinsulin, C-peptide and PI:C correlated significantly (r(2) = 0.96-0.99; P<0.001) with results obtained with separate methods. TT-TRFIA achieved better between-day % CV for PI:C at three different levels (4.5-7.1 vs 6.7-9.5 for separate methods). In high-risk relatives fasting PI:C was significantly and inversely correlated ( r(s) = -0.596; P<0.001) with first-phase C-peptide release during clamp ( also with second phase release, only available for age 12-39 years; n = 31), but only after normalization for HOMA2-IR. In ROC- and Cox regression analysis, HOMA2-IR-corrected PI:C predicted 2-year progression to diabetes equally well as clamp-derived C-peptide release. Conclusions : The reproducibility of PI:C benefits from the automated simultaneous determination of both hormones. HOMA2-IR-corrected PI:C may serve as a minimally invasive alternative to the more tedious hyperglycemic clamp test

Insulin treatment in IA-2A-positive relatives of type 1 diabetic patients.

We examined whether parenteral regular insulin can prevent diabetes in IA-2 antibody-positive (IA-2A+) relatives of type 1 diabetic patients, using a trial protocol that differed substantially from that of the Diabetes Prevention Trial-1. Twenty-five IA-2A+ relatives received regular human insulin twice a day for 36 months, during which time they were followed (median [interquartile range; IQR]: 47 [19-66] months) for glucose tolerance, HbA(1c) and islet autoantibodies, together with 25 IA-2A+ relatives (observation/control group) who fulfilled the same inclusion criteria, but were observed for 52 [27-67] months (P=0.58). Twelve (48%) insulin-treated relatives and 15 (60%) relatives in the control group developed diabetes. There was no difference in diabetes-free survival between the two groups (P=0.97). Five-year progression (95% confidence interval) was 44% (25-69) in the insulin-treated group and 49% (29-70) in the observation group. At inclusion, progressors tended to have a higher pro-insulin/C-peptide ratio than non-progressors when measured 2 hours after a standardized glucose load (median [IQR]: 2.7% [1.8-4.3] vs. 1.6% [1.1-2.1]; P=0.01). No major hypoglycaemic episodes or significant increases in body mass index or diabetes autoantibodies were observed. Prophylactic injections of regular human insulin were well tolerated, but failed to prevent type 1 diabetes onset in IA-2A+ relatives

CTLA4, SH2B3, and CLEC16A diversely affect the progression of early islet autoimmunity in relatives of Type 1 diabetes patients

The HLA region is the major genetic risk determinant of Type 1 diabetes. How non-HLA loci contribute to the genetic risk is incompletely understood, but there are indications that at least some impact progression of asymptomatic autoimmunity. We examined whether SNPs in 7 susceptibility loci (INS, SH2B3, PTPN2, PTPN22, CTLA4, CLEC16A, and IL2RA) could improve prediction of the progression from single to multiple autoantibody positivity, and from there on to diagnosis. SNPs were genotyped in persistently autoantibody positive relatives by allelic discrimination qPCR and disease progression was studied by multivariate Cox regression analysis. In our cohort, only the CTLA4 GA genotype (rs3087243, P = 0.002) and the CLEC16A AA genotype (rs12708716, P = 0.021) were associated with accelerated progression from single to multiple autoantibody positivity, but their effects were restricted to presence of HLA-DQ2/DQ8, and IAA as first autoantibody, respectively. The interaction of CTLA4 and HLA-DQ2/DQ8 overruled the effect of DQ2/DQ8 alone. The HLA-DQ2/DQ8-mediated risk of progression to multiple autoantibodies nearly entirely depended on heterozygosity for CTLA4. The SH2B3 TT genotype (rs3184504) was protective for HLA-DQ8 positive subjects (P = 0.003). At the stage of multiple autoantibodies, only the CTLA4 GA genotype was a minor independent risk factor for progression towards clinical diabetes (P = 0.034). Our study shows that non-HLA polymorphisms impact progression of islet autoimmunity in a subgroup-, stage- and SNP-specific way, suggesting distinct mechanisms. If confirmed, these findings may help refine risk assessment, follow-up, and prevention trials in risk groups.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

IA-2 autoantibodies predict impending type I diabetes in siblings of patients.

Multiple islet autoantibody positivity is currently believed to best predict progression to Type I (insulin-dependent) diabetes mellitus. We compared its predictive value with that of positivity for a particular type of islet autoantibody, directed against the IA-2 antigen. Autoantibodies against islet cell cytoplasm (ICA), insulin (IAA), GAD (GADA) and IA-2 (IA-2A) were measured at initial sampling in 1724 non-diabetic siblings (median age [range]:16 [0-39] years) of Type I diabetic patients with a median follow-up of 50 months. On initial sampling 11% of siblings were positive for one antibody type or more and 2.1% for three of more types. During follow-up, 27 antibody-positive siblings developed diabetes. Using survival analysis, the risk for clinical onset within 5 years was 34% in subjects positive for three or more types compared with 13% in those with one type or more. Progression to diabetes amounted to 12% within 5 years among siblings positive for IAA, 20% for ICA, 19% for GADA but 59% for IA-2A (p<0.001 vs absence of the respective antibody). IA-2A were detected in 1.7% of all siblings and in 56% of the prediabetic subjects on first sampling. Initial positivity for two or three antibody markers was associated with a higher progression rate in IA-2A positive as compared to IA-2A negative siblings (p=0.001). In absence of IA-2A initial positivity for another antibody (IAA, ICA or GADA) conferred a low (<10% within 5 years) risk of diabetes compared to subjects lacking this antibody. In siblings of Type I diabetic patients, IA-2A positivity is a more direct predictor of impending clinical onset than multiple antibody positivity per se. Assessment of IA-2A status allows us to select subjects with homogeneously high risk of diabetes for participation in prevention trials

Seasonality in clinical onset of type 1 diabetes in belgian patients above the age of 10 is restricted to HLA-DQ2/DQ8-negative males, which explains the male to female excess in incidence.

Type 1 diabetes arises from an interplay between environmental and genetic factors. The reported seasonality at diagnosis supports the hypothesis that currently unknown external triggers play a role in the onset of the disease. We investigated whether a seasonal pattern is observed at diagnosis in Belgian Type 1 diabetic patients, and if so whether seasonality varies according to age, sex and genetic risk, all known to affect the incidence of Type 1 diabetes.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

HLA-A*24 is an independent predictor of 5-year progression to diabetes in autoantibody-positive first-degree relatives of type 1 diabetic patients

We investigated whether HLA-A*24 typing complements screening for HLA-DQ and for antibodies (Abs) against insulin, GAD, IA-2 (IA-2A), and zinc transporter-8 (ZnT8A) for prediction of rapid progression to type 1 diabetes (T1D). Persistently Ab+ siblings/offspring (n = 288; aged 0-39 years) of T1D patients were genotyped for HLA-DQA1-DQB1 and HLA-A*24 and monitored for development of diabetes within 5 years of first Ab+. HLA-A*24 (P = 0.009), HLA-DQ2/DQ8 (P = 0.001), and positivity for IA-2A ± ZnT8A (P < 0.001) were associated with development of T1D in multivariate analysis. The 5-year risk increased with the number of the above three markers present (n = 0: 6%; n = 1: 18%; n = 2: 46%; n = 3: 100%). Positivity for one or more markers identified a subgroup of 171 (59%) containing 88% of rapid progressors. The combined presence of HLA-A*24 and IA-2A+ ± ZnT8A+ defined a subgroup of 18 (6%) with an 82% diabetes risk. Among IA-2A+ 6 ZnT8A+ relatives, identification of HLA-A*24 carriers in addition to HLA-DQ2/DQ8 carriers increased screening sensitivity for relatives at high Ab-and HLA-inferred risk (64% progression; P = 0.002). In conclusion, HLA-A*24 independently predicts rapid progression to T1D in Ab+ relatives and complements IA-2A, ZnT8A, and HLA-DQ2/DQ8 for identifying participants in immunointervention trials. © 2013 by the American Diabetes Association.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Repeated OGTT versus continuous glucose monitoring for predicting development of stage 3 type 1 diabetes : a longitudinal analysis

OBJECTIVE Evidence for using continuous glucose monitoring (CGM) as an alternative to oral glucose tolerance tests (OGTTs) in presymptomatic type 1 diabetes is primarily cross-sectional. We used longitudinal data to compare the diagnostic performance of repeated CGM, HbA(1c), and OGTT metrics to predict progression to stage 3 type 1 diabetes. RESEARCH DESIGN AND METHODS Thirty-four multiple autoantibody-positive first-degree relatives (FDRs) (BMI SD score [SDS] <2) were followed in a multicenter study with semiannual 5-day CGM recordings, HbA(1c), and OGTT for a median of 3.5 (interquartile range [IQR] 2.0-7.5) years. Longitudinal patterns were compared based on progression status. Prediction of rapid (<3 years) and overall progression to stage 3 was assessed using receiver operating characteristic (ROC) areas under the curve (AUCs), Kaplan-Meier method, baseline Cox proportional hazards models (concordance), and extended Cox proportional hazards models with time-varying covariates in multiple record data (n = 197 OGTTs and concomitant CGM recordings), adjusted for intraindividual correlations (corrected Akaike information criterion [AICc]). RESULTS After a median of 40 (IQR 20-91) months, 17 of 34 FDRs (baseline median age 16.6 years) developed stage 3 type 1 diabetes. CGM metrics increased close to onset, paralleling changes in OGTT, both with substantial intra- and interindividual variability. Cross-sectionally, the best OGTT and CGM metrics similarly predicted rapid (ROC AUC = 0.86-0.92) and overall progression (concordance = 0.73-0.78). In longitudinal models, OGTT-derived AUC glucose (AICc = 71) outperformed the best CGM metric (AICc = 75) and HbA(1c) (AICc = 80) (all P < 0.001). HbA(1c) complemented repeated CGM metrics (AICc = 68), though OGTT-based multivariable models remained superior (AICc = 59). CONCLUSIONS In longitudinal models, repeated CGM and HbA(1c) were nearly as effective as OGTT in predicting stage 3 type 1 diabetes and may be more convenient for long-term clinical monitoring.OBJECTIVE Evidence for using continuous glucose monitoring (CGM) as an alternative to oral glucose tolerance tests (OGTTs) in presymptomatic type 1 diabetes is primarily cross-sectional. We used longitudinal data to compare the diagnostic performance of repeated CGM, HbA(1c), and OGTT metrics to predict progression to stage 3 type 1 diabetes. RESEARCH DESIGN AND METHODS Thirty-four multiple autoantibody-positive first-degree relatives (FDRs) (BMI SD score [SDS] <2) were followed in a multicenter study with semiannual 5-day CGM recordings, HbA(1c), and OGTT for a median of 3.5 (interquartile range [IQR] 2.0-7.5) years. Longitudinal patterns were compared based on progression status. Prediction of rapid (<3 years) and overall progression to stage 3 was assessed using receiver operating characteristic (ROC) areas under the curve (AUCs), Kaplan-Meier method, baseline Cox proportional hazards models (concordance), and extended Cox proportional hazards models with time-varying covariates in multiple record data (n = 197 OGTTs and concomitant CGM recordings), adjusted for intraindividual correlations (corrected Akaike information criterion [AICc]). RESULTS After a median of 40 (IQR 20-91) months, 17 of 34 FDRs (baseline median age 16.6 years) developed stage 3 type 1 diabetes. CGM metrics increased close to onset, paralleling changes in OGTT, both with substantial intra- and interindividual variability. Cross-sectionally, the best OGTT and CGM metrics similarly predicted rapid (ROC AUC = 0.86-0.92) and overall progression (concordance = 0.73-0.78). In longitudinal models, OGTT-derived AUC glucose (AICc = 71) outperformed the best CGM metric (AICc = 75) and HbA(1c) (AICc = 80) (all P < 0.001). HbA(1c) complemented repeated CGM metrics (AICc = 68), though OGTT-based multivariable models remained superior (AICc = 59). CONCLUSIONS In longitudinal models, repeated CGM and HbA(1c) were nearly as effective as OGTT in predicting stage 3 type 1 diabetes and may be more convenient for long-term clinical monitoring.A