Prevalence of Islet Autoantibodies in Adults Without Diabetes

Family history of type 2 diabetes (T2D) is an important but neglected parameter; however, its role in identifying the heterogeneity and subtypes of type 1 diabetes (T1D) remains unclear. We investigated the effect of family history of T2D on the clinical phenotype of T1D patients and evaluated its value in T1D classification. A total of 1410 T1D patients were enrolled in this prospective study. Information on family history of T2D in first-degree relatives (FDRs) was collected by research nurses using a semi-structured questionnaire as previously described. The effect of family history of T2D on clinical characteristics was evaluated in overall and subgroups of T1D patients stratified by islet autoantibodies, onset age, and human leukocyte antigen (HLA) genotype. Cluster analysis was performed to identify family history of T2D-related subgroups. A total of 10% (141/1410) of patients had at least 1 FDR diagnosed with T2D. A milder phenotype associated with family history of T2D was present in overall T1D patients, including older onset age (P < .001), higher body mass index (P < .001), higher fasting and postprandial C-peptide levels (all P < .01), lower positive rates of all islet autoantibodies, and susceptible HLA genotypes (all P < .05). Clinical heterogeneity associated with family history of T2D in the T1D subgroup stratified by autoimmunity, age of onset, and HLA genotypes was consistent. Using family history of T2D as a cluster variable, T1D patients were divided into 5 clusters, and patients in the T2D family history cluster displayed a milder phenotype than others. Family history of T2D should be considered as an important indicator for precise subclassification of T1D patients based on clinical heterogeneity.

Detection of type 1 diabetes (T1D) at the preclinical stage is possible by detecting islet autoantibodies (IAs) years before the appearance of symptomatic diabetes. The Antibody Detection Israeli Research is a general population screening program searching for children with multiple IAs who are at risk of developing T1D. IAs are measured in capillary or venous whole blood (WB) samples using the novel ultrasensitive antibody detection by agglutination-PCR (ADAP) technology. To assess the accuracy and reliability of the ADAP assay in venous and capillary WB. In total, 50 children with T1D and 50 healthy controls participated in the study. Venous and capillary blood samples were drawn from participants with T1D, while only venous blood was drawn from the controls. The ADAP assay in venous and capillary blood was compared to the currently used assays in their ability to detect glutamic acid decarboxylase (GADA), islet antigen-2 (IA-2A), and insulin autoantibodies (IAAs). The area under the curve using the receiver operating characteristic curves was comparable between the ADAP assay in WB and standard enzyme-linked immunosorbent assay (ELISA)/radioimmunoassay (RIA) for all three IAs GADA 0.946 (95% CI: 0.900-0.991) vs. 0.949 (0.906-0.992), P=0.873; IA-2A 0.747 (0.649-0.844) vs. 0.666 (0.587-0.744), P=0.106; IAA 1.000 (1.000-1.000) vs. 1.000 (1.000-1.000), P=1.000. The correlation between the levels of IA in venous and capillary WB using ADAP was R 2 = 0.958 (P < 0.01), R 2 = 0.943 (P < 0.01), and R 2 = 0.711 (P < 0.01) for GADA, IA-2A, and IAA, respectively. IA levels in venous and capillary WB using ADAP were comparable without a proportional bias in Bland-Altman's plots of agreement, suggesting the two methods may be used interchangeably. The ADAP assay is reliable in detecting IA in venous and capillary WB samples with comparable performance to standard RIA and ELISA. These findings open avenues for widespread use of the ADAP assay in future general population screening programs to detect children at risk of developing T1D.

Ambient air pollution and early manifestation of type 1 diabetes.

Background: Screening for presymptomatic type 1 diabetes (T1D) reduces the risk of diabetic ketoacidosis (DKA) and allows for early intervention with disease-modifying therapies. Despite the rising incidence of T1D in Bulgaria, screening initiatives remain limited. This pilot study aims to evaluate the feasibility of selective T1D screening in high-risk children and identify potential clinical associations with islet autoimmunity. Methods: The study targeted a recruitment of 250 children aged 0-18 years (200 with a relative with T1D and 50 without). Screening for islet autoantibodies (AABs), including glutamic acid decarboxylase (GADA), insulin (IAA), insulinoma-associated-2 (IA-2A), zinc transporter-8 (ZnT8A), and islet cell cytoplasmic autoantibodies (ICAs), was performed via chemiluminescence immunoassay (CLIA). Participants testing positive for one or more AABs were scheduled for longitudinal immunological and metabolic follow-up to evaluate the persistence of autoimmunity and disease progression. Results: Between October 2024 and February 2026, the pilot study recruited 210 participants (84% of the 250 target), including 160 children with a relative (target 200) and 50 without a family history of T1D (target 50). Within the high-risk group, seven children (4.4%) tested positive for a single autoantibody (3 GADA, 2 ZnT8A, 1 IA-2A, and 1 IAA), while no autoantibodies were detected in the group without a relative. No cases of multiple autoantibody positivity or stage 3 T1D were identified in either group. Furthermore, no statistically significant associations were observed between autoantibody positivity and secondary factors, including breastfeeding, allergic status, a high-glycemic diet, frequent illness, and personal history of autoimmune disease. Conclusions: The findings validate the feasibility of selective T1D screening in Bulgaria, driven by high public interest and successful recruitment across both high-risk and general population cohorts. While this exploratory study found no significant clinical correlations, it establishes a vital roadmap for larger, longitudinal research. Ultimately, this pilot framework provides a scalable model for implementing standardized early detection to reduce the burden of T1D on the national healthcare system.

To investigate the prevalence, clinical significance and antepartum to postpartum trajectory of zinc transporter 8 autoantibodies, a novel marker of islet autoimmunity, in women with gestational diabetes mellitus. A total of 302 consecutive women attending a multi-ethnic Australian gestational diabetes clinic were prospectively studied. Zinc transporter 8 autoantibodies were measured at gestational diabetes diagnosis and 3months postpartum using an enzyme-linked immunosorbent assay, and were correlated with maternal phenotype, antepartum and postpartum glucose tolerance, treatment and perinatal outcomes. Of the 302 women, 30 (9.9%) were positive for one islet autoantibody antepartum. No participant had multiple islet autoantibodies. Zinc transporter 8 autoantibodies were the most prevalent autoantibody [zinc transporter 8 autoantibodies: 13/271 women (4.8%); glutamic acid decarboxylase 7/302 women (2.3%); insulinoma-associated antigen-2: 6/302 women (2.0%); insulin: 4/302 women (1.3%)]. Zinc transporter 8 autoantibody positivity was associated with a higher fasting glucose level on the antepartum oral glucose tolerance test, but not with BMI, insulin use, perinatal outcomes or postpartum glucose intolerance. Five of the six women who tested positive for zinc transporter 8 autoantibodies antepartum were negative for zinc transporter 8 autoantibodies postpartum, which corresponded to a significant decline in titre antepartum to postpartum (26.5 to 3.8 U/ml; P=0.03). This was in contrast to the antepartum to postpartum trajectory of the other islet autoantibodies, which remained unchanged. Zinc transporter 8 autoantibodies were the most common islet autoantibody in gestational diabetes. Zinc transporter 8 autoantibody positivity was associated with slightly higher fasting glucose levels and, unlike other islet autoantibodies, titres declined postpartum. Zinc transporter 8 autoantibodies may be a marker for islet autoimmunity in a proportion of women with gestational diabetes, but the clinical relevance of zinc transporter 8 autoantibodies in pregnancy and gestational diabetes requires further investigation.

Type 1 diabetes (T1D) is an autoimmune disease caused by the destruction of insulin producing beta-cells in the pancreas. Individuals with T1D cannot survive without insulin replacement, and despite daily insulin treatment remain at risk of complications including nephropathy, retinopathy and coronary heart disease. Although commonly associated with onset in childhood and adolescence with a peak age at diagnosis of 12 years, many cases of T1D are diagnosed in adulthood. Epidemiological studies show that the incidence of T1D is unequally distributed in the world’s population, with a high incidence rate in Caucasians (40/100 000/year in Finland) and an extremely low rate among Asian and South American populations (0.1/100 000/year) (Karvonen et al., 2000). T1D is increasingly considered a disease of “westernization” or affluence associated with improved hygiene, healthcare and living standards. The incidence of the condition has been increasing rapidly in recent decades for unknown reasons: the current rate of increase is 3% per year worldwide and it has been predicted that the incidence will be 40% higher by 2010 compared to 1998 (Onkamo et al., 1999). More recent predictions show that if present trends continue, doubling of new cases of type 1 diabetes in European children younger than 5 years will occur between 2005 and 2020, and prevalent cases younger than 15 years will rise by 70% (Patterson et al., 2009). T1D is generally diagnosed on clinical grounds but can be confirmed by the presence of circulating antibodies in the blood (Baekkeskov et al., 1982). These antibodies are markers of ongoing autoimmune destruction (Bottatzo et al., 1985) and the best characterized are specific to the islet proteins insulin (Palmer et al., 1983), glutamic acid decarboxylase (GAD) (Baekkeskov et al., 1990), IA-2 ( Christie et al., 1994) and the zinc transporter ZnT8 (Wenzlau et al., 2007, 2008). The autoimmune process begins very early in life: studies of neonatal diabetes suggest that most cases of diabetes diagnosed before 6 months are unlikely to be autoimmune, but those diagnosed after the age of 6 months have the genetic characteristics of T1D (Edghill et al., 2006) while islet autoantibodies are detectable by 5 years of age in most future T1D cases (Bonifacio et al., 2004 ); in many by 2 years of age (Zeigler et al., 1999), and antibodies to insulin (generally the first to appear) have been detected as early as 6 to 12 months of age (Roll et al., 1996). T1D can be predicted accurately by the detection of multiple islet autoantibodies and their characteristics (Bingley et al. 1997; Achenbach et al., 2004a, 2004b). Trials of agents to prevent T1D however require identification of those at risk of T1D very early in life before the autoimmune process has been initiated. This is only possible by estimation of genetic risk.

Introduction and Objective: Total pancreatectomy with islet auto transplantation (TPIAT) is a non-immune model of islet transplant. The presence of islet autoantibodies post TPIAT has been observed, but the impact on β cell function is unknown. We compared measures of β cell function between children who were islet autoantibody positive (IAP) and negative (IAN) for up to 2 years post TPIAT. Methods: Clinical data was collected from children who underwent TPIAT between 2015 and 2021. All patients were screened for islet autoantibodies and underwent Mixed Meal Tolerance Testing (MMTT) at 12 months and 18-24 months post TPIAT. IAP was defined as the detection of one or more of the following: Glutamic Acid Decarboxylase (GAD), Islet Antigen-2 (IA-2), or Zinc Transporter 8 (ZnT8). Insulin Antibody (IAA) was excluded due to the likelihood that detection was secondary to exogenous insulin exposure. At 12 months, 23 patients were identified: 7 IAP and 16 IAN. At 18-24 months, 20 patients were identified: 7 IAP and 13 IAN. Results: There were no differences in age at TPIAT, sex, or HbA1C levels between patients who were IAP or IAN. At 12 months post TPIAT, insulinogenic index, peak C peptide, C peptide secretion index and area under the curve C peptide were higher in the IAP group. BMI was significantly higher in the IAP group at 12 and 18-24 months. At 18-24 months, although not statistically significant, the median age was lower in the IAN group. Conclusion: The role of islet autoantibodies on β cell function post TPIAT remains unclear. IAP group is associated with increased insulin secretion post TPIAT. These data suggest that age and BMI influenced insulin secretion more than the presence of islet autoantibodies over this short post TPIAT duration. We suspect a longer exposure to islet antibodies is required to assess impact on β cell function. Disclosure O. Kothawala: None. L. Hornung: None. A.R. Lavik: None. S. Swauger: None. C.M.O. Lowe: None. M. Abu-El-Haija: None. S.E. Tellez: None. D.A. Elder: Research Support; Dexcom, Inc., Sanofi.

Objective To explore the distribution characteristics of islet autoantibodies and other organ-specific autoantibodies in type 1 diabetes mellitus (T1DM) patients, and the correlation between organ-specific autoantibodies and clinical features. Methods A total of 205 newly diagnosed T1DM patients and 170 healthy controls were recruited in this study from the Second Xiangya Hospital of Central South University between Jan. 2015 and Dec. 2017. Glutamic acid decarboxylase antibody (GADA), insulinoma antigen 2 antibody (IA-2A), zinc transporter 8 antibody (ZnT8A) and other organ-specific autoantibodies, including thyroid peroxidase antibody (TPOA), thyroglobulin antibody (TGA), tissue transglutaminase antibody (tTGA) and 21-hydroxylase antibody (21-OHA) were detected by radioligand assay. In antibody-positive patients the function of thyroid and adrenal cortex was further examined; the coexistence of islet antibodies with other organ-specific autoantibodies, and the correlation between organ-specific antibodies and clinical characteristics were analyzed. Chi-square test, one-way analysis of variance and non-parametric test were used for statistical analysis. Results (1) The positive rates of GADA, IA-2A and ZnT8A in patients with T1DM were significantly higher than those in healthy controls [70.2% (144/205) vs 0.6%(1/170), 42.9%(88/205) vs 0 and 30.7%(63/205) vs 0 (0/170), χ2=190.131, 95.357, 62.792, respectively, all P 0.05). (3) In T1DM patients the detections of combining various islet autoantibodies (GADA+IA-2A+ZnT8A) could increase the positive rate to 82.9%. (4) T1DM patients with positive GADA and IA-2A were more likely to have positive TPOA and TGA antibodies, patients with positive IA-2A were more likely to have positive tTGA antibodies, and patients with two or more islet autoantibodies were more likely to have positive TPOA and TGA antibodies. (5) The proportion of T1DM patients with Graves′ disease was higher than that of healthy controls (4.4% vs 0.6%, P<0.05). Conclusions T1DM patients are prone to merge other organ-specific autoantibodies. It is of great clinical significance to screen other organ specific autoantibodies, especially in T1DM patients with positive polyantibodies. Key words: Diabetes mellitus, type 1; Islet autoantibody; Organ-specific autoantibody

To establish the diagnostic sensitivity of and the relationships between autoantibodies to all three Zinc transporter 8 (Zinc transporter 8 autoantibody to either one, two, or all three amino acid variants at position 325, ZnT8A) variants to human leukocyte antigen (HLA)-DQ and to autoantibodies to glutamic acid decarboxylase (GADA), insulinoma-associated protein 2 (IA-2A), and insulin (IAA). We analyzed 3165 patients with type 1 diabetes (T1D) in the Better Diabetes Diagnosis study for HLA-DQ genotypes and all six autoantibodies (ZnT8RA, arginine 325 Zinc transporter 8 autoantibody; ZnT8WA, tryptophan 325 Zinc transporter 8 autoantibody; ZnT8QA, glutamine 325 Zinc transporter 8 autoantibody; GADA, IA-2A, and IAA). ZnT8A was found in 65% of the patients and as many as 108 of 3165 (3.4%) had 1-3 ZnT8A alone. None had ZnT8QA alone. Together with GADA (56%), IA-2A (73%), and IAA (33%), 93% of the T1D patients were autoantibody positive. All three ZnT8A were less frequent in children below 2 yr of age (p < 0.0001). All three ZnT8A were associated with DQA1-B1*X-0604 (DQ6.4) and DQA1-B1*03-0302 (DQ8). ZnT8WA and ZnT8QA were negatively associated with DQA1-B1*05-02 (DQ2). Analysis of ZnT8A increased the diagnostic sensitivity of islet autoantibodies for T1D as only 7% remained islet autoantibody negative. The association between DQ6.4 and all three ZnT8A may be related to ZnT8 antigen presentation by the DQ6.4 heterodimer.

An ongoing clinical trial, Autoimmunity Screening for Kids (ASK), is the first screening study in the general population for type 1 diabetes (T1D) and celiac disease in the United States. With the coronavirus disease 2019 (COVID-19) pandemic, the epidemiology of COVID-19 in the general population and knowledge about the association between COVID-19 infection and T1D development are urgently needed. The currently standard screening method of the radio-binding assay (RBA) has met two great challenges: low efficiency with a single assay format and low disease specificity with a large proportion of low-affinity antibodies generated in screening. With the platform of the multiplex electrochemiluminescence (ECL) assay we established previously, a novel 6-Plex ECL assay was developed that combines, in a single well, all four islet autoantibodies (IAbs) to insulin, glutamic acid decarboxylase (GAD65), insulinoma antigen 2 (IA-2), and Zinc transporter 8 (ZnT8) for T1D, transglutaminase autoantibodies (TGA) for celiac disease, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain (RBD) antibodies for COVID-19. The assay was validated in blind using 880 samples from the ASK study, including 325 positive samples and 555 all antibody-negative samples, and compared with the standard RBAs and a single ECL assay. With the advantages of high efficiency, low cost, and low serum volume, this assay has been accepted as the primary screening tool for the ASK study.

An ongoing clinical trial, Autoimmunity Screening for Kids (ASK), is the first screening study in the general population for type 1 diabetes (T1D) and celiac disease in the United States. With the coronavirus disease 2019 (COVID-19) pandemic, the epidemiology of COVID-19 in the general population and knowledge about the association between COVID-19 infection and T1D development are urgently needed. The currently standard screening method of the radio-binding assay (RBA) has met two great challenges: low efficiency with a single assay format and low disease specificity with a large proportion of low-affinity antibodies generated in screening. With the platform of the multiplex electrochemiluminescence (ECL) assay we established previously, a novel 6-Plex ECL assay was developed that combines, in a single well, all four islet autoantibodies (IAbs) to insulin, glutamic acid decarboxylase (GAD65), insulinoma antigen 2 (IA-2), and Zinc transporter 8 (ZnT8) for T1D, transglutaminase autoantibodies (TGA) for celiac disease, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain (RBD) antibodies for COVID-19. The assay was validated in blind using 880 samples from the ASK study, including 325 positive samples and 555 all antibody-negative samples, and compared with the standard RBAs and a single ECL assay. With the advantages of high efficiency, low cost, and low serum volume, this assay has been accepted as the primary screening tool for the ASK study.

For cost-effective population-based diabetes prediction and confirmation, islet autoantibody assays must be made more economical. We evaluated glutamic acid decarboxylase (GAD)-Ruc (renilla luciferase) and IA2ic (also known as ICA512ic)-Ruc (renilla luciferase) fusion protein constructs in high-throughput islet antibody assay formats. Antigen production via transfection onto COS cells in 100 mm culture dishes yielded sufficient antigen to assay 375 and 535 serum samples for GAD and IA2ic per dish, respectively. Antigen was usably stable after -80 °C storage for 40-80 days after which luciferase activity decreased. The mean signal-to-noise ratios for luciferase-based immunoprecitation system (LIPS) GAD and LIPS IA2ic were 88±24 and 219±89, respectively, comparing favourably to radio-binding assays (RBA) in the same format. However, the coefficient of variation among triplicate wells was higher for IA2ic than for GAD in LIPS, similar to findings in RBA format. Correlation coefficients between autoantibody indices determined from the RBA and LIPS methods were only R2=0.79 and R2=0.75 for GAD and IA2ic, respectively, raising the possibility that different epitopes were favoured in the two different assay formats. Nevertheless, overall concordance for the two assay types was high, at 228/240=95.0% for GAD and 494/521=94.8% for IA2ic. Using optimal cutoffs, Diabetes Autoantibody Standardization Program (DASP) 2010 sensitivity/specificity was 80/99% for GAD RBA, 80/99% for GAD LIPS, 70/98% for IA2 RBA, and 72/99% for IA2 LIPS. The LIPS assays for islet autoantibodies to GAD and IA2ic performed as well as RBA in DASP 2010. With further refinements in expression and storage, these assays may be more economical than current methods to measure islet autoantibodies in type 1 diabetes.

Objective To investigate the role of human leukocyte antigen (HLA) DQ haplotype for immunoetiologic chassification of idiopathic type 1 diabetes by comparison of clinical features, zinc transporter 8 autoantibodies (ZnT8A), glutamic acid decarboxylase 65(GAD65)-reactive interferon-γ-secreting T cells (GAD65-IFN-γ-T cells). Methods Fifty-two patients of Han People of Hunan Province origin with newly onset idiopathic type 1 diabetes were enrolled in this study from March 2000 to December 2011. The criteria for enrolment included: new-onset, unprovoked ketosis or ketoacidosis at onset; negative glutamic acid decarboxylase antibody(GADA), protein tyrosinephosphatase antibody (IA-2A) and insulin autoantibody(IAA); permanent insulin deficiency. ZnT8A were detected in all patients with radioligand assay. GAD65-IFN-γ-T cells were tested by enzyme linked immune spot (ELISPOT) in ZnT8A-negative patients. HLA-DQA1 and DQB1 alleles were identified with polymerase chain reaction(PCR) sequence-based genotyping (SBT). According to the situation of HLA-DQ susceptible haplotypes, patients with HLA-DQ genotyping were categorized into two groups, and were all visited annually for 3 consecutive years. Comparisons were made between the two groups in their clinical characteristics, ZnT8A and GAD65-IFN-γ-T cell status. Compare of qualitative data between two groups was progressed by using chi-square test. Results In this study group, ZnT8A was positive in 5 cases out of 52 (9.6%), and GAD65-IFN-γ-T cells were positive in 2 cases out of 16 patients with ZnT8A negative (12.5%). More severe diabetic ketoacidosis(DKA)(Z=-2.84, P<0.05) and lower fasting C protein(FCP) levels(χ2=0.38, P<0.05) at onset were observed in patients with HLA-DQ susceptible haplotypes. During the onset, GAD65-IFN-γ-T cells was positive in 1 patient carrying HLA-DQ susceptible haplotypes and there was none in patients with non-susceptible HLA-DQ haplotypes. Islet autoantibodies (ZnT8A and IA-2A) turned positive in 1 patient with HLA-DQ susceptible haplotypes(1/18), while none was observed in patients with non-HLA-DQ susceptible haplotypes during the 3-year visit. Conclusions ZnT8A and GAD65-IFN-γ-T cells exist in some patients with idiopathic type 1 diabetes.The patients with idiopathic type 1 diabetes carry HLA-DQ susceptible haplotypes, compared with those without HLA-DQ haplotypes, present a autoimmune tendency.It implies that islet autoimmunity, to some extent, could be an etiology of idiopathic type 1 diabetes, which is probably mediated by HLA-DQ hapalotype. Key words: Diabetes mellitus, type 1; Human leukocyte antigen; Classification; Immunology

ObjectiveType 1 diabetes (T1D) screening programmes testing islet autoantibodies (IAbs) in childhood can reduce life-threatening diabetic ketoacidosis. General population screening is required to detect the majority of children with T1D,...

Type 1 diabetes (T1D) is now a predictable disease with the measurement of antibodies in the peripheral blood directed against proteins within insulin-producing β-cells.1 There are currently four main biochemical islet autoantibodies measured that are directed against insulin, glutamic acid decarboxylase, islet antigen 2, and zinc transporter 8. The presence of two or more islet autoantibodies in children with a first-degree relative having T1D indicates preclinical T1D as nearly 100% of these children develop diabetes, marked by abnormal glucose homeostasis, provided long-term follow-up.2