IA-2 Autoantibodies Research Articles

Oral Insulin Delay of Stage 3 Type 1 Diabetes Revisited in HLA DR4-DQ8 Participants in the TrialNet Oral Insulin Prevention Trial (TN07).

To explore if oral insulin could delay onset of stage 3 type 1 diabetes (T1D) among patients with stage 1/2 who carry HLA DR4-DQ8 and/or have elevated levels of IA-2 autoantibodies (IA-2As). Next-generation targeted sequencing technology was used to genotype eight HLA class II genes (DQA1, DQB1, DRB1, DRB3, DRB4, DRB5, DPA1, and DPB1) in 546 participants in the TrialNet oral insulin preventative trial (TN07). Baseline levels of autoantibodies against insulin (IAA), GAD65 (GADA), and IA-2A were determined prior to treatment assignment. Available clinical and demographic covariables from TN07 were used in this post hoc analysis with the Cox regression model to quantify the preventive efficacy of oral insulin. Oral insulin reduced the frequency of T1D onset among participants with elevated IA-2A levels (HR 0.62; P = 0.012) but had no preventive effect among those with low IA-2A levels (HR 1.03; P = 0.91). High IA-2A levels were positively associated with the HLA DR4-DQ8 haplotype (OR 1.63; P = 6.37 × 10-6) and negatively associated with the HLA DR7-containing DRB1*07:01-DRB4*01:01-DQA1*02:01-DQB1*02:02 extended haplotype (OR 0.49; P = 0.037). Among DR4-DQ8 carriers, oral insulin delayed the progression toward stage 3 T1D onset (HR 0.59; P = 0.027), especially if participants also had high IA-2A level (HR 0.50; P = 0.028). These results suggest the presence of a T1D endotype characterized by HLA DR4-DQ8 and/or elevated IA-2A levels; for those patients with stage 1/2 disease with such an endotype, oral insulin delays the clinical T1D onset.

Inaccurate diagnosis of diabetes type in youth: prevalence, characteristics, and implications.

Classifying diabetes at diagnosis is crucial for disease management but increasingly difficult due to overlaps in characteristics between the commonly encountered diabetes types. We evaluated the prevalence and characteristics of youth with diabetes type that was unknown at diagnosis or was revised over time. We studied 2073 youth with new-onset diabetes (median age [IQR] = 11.4 [6.2]years; 50% male; 75% White, 21% Black, 4% other race; overall, 37% Hispanic) and compared youth with unknown versus known diabetes type, per pediatric endocrinologist diagnosis. In a longitudinal subcohort of patients with data for ≥ 3years post-diabetes diagnosis (n = 1019), we compared youth with steady versus reclassified diabetes type. In the entire cohort, after adjustment for confounders, diabetes type was unknown in 62 youth (3%), associated with older age, negative IA-2 autoantibody, lower C-peptide, and no diabetic ketoacidosis (all, p < 0.05). In the longitudinal subcohort, diabetes type was reclassified in 35 youth (3.4%); this was not statistically associated with any single characteristic. In sum, among racially/ethnically diverse youth with diabetes, 6.4% had inaccurate diabetes classification at diagnosis. Further research is warranted to improve accurate diagnosis of pediatric diabetes type.

Impact of GAD65 and IA2 autoantibodies on islet allograft survival.

Islet transplantation (ITx) shows promise in treating T1D, but the role of islet autoantibodies on graft survival has not been clearly elucidated. We aimed to analyze the effect of GAD65 and IA2 autoantibody status on graft survival and attainment of insulin independence in subjects with T1D who underwent ITx. We conducted a retrospective cohort study on 47 ITx recipients from 2000 to 2018. Islet infusion was performed via intrahepatic portal (n=44) or onto the omentum via laparoscopic approach (n=3). Immunosuppression involved anti-IL2 receptor antibody, anti-TNF, and dual combinations of sirolimus, tacrolimus, or mycophenolate mofetil (Edmonton-like) in 38 subjects (80.9%). T-cell depletion induction with Edmonton-like maintenance was used in 9 subjects (19%). GAD65 and IA2 autoantibodies were assessed pre-transplant and post-transplant (monthly) until graft failure, and categorized as persistently negative, persistently positive, or seroconverters. Graft survival was analyzed using U-Mann-Whitney test, and Quade's nonparametric ANCOVA adjusted for confounders. Kaplan-Meier and Log-Rank tests were employed to analyze attainment of insulin independence. P value <0.05 indicated statistical significance. ITx recipients with persistent autoantibody negativity (n = 21) showed longer graft function (98 [61 - 182] months) than those with persistent autoantibody positivity (n = 18; 38 [13 - 163] months), even after adjusting for immunosuppressive induction protocol (P = 0.027). Seroconverters (n=8) had a median graft survival time of 73 (7.7 - 167) months, which did not significantly differ from the other 2 groups. Subjects with persistently single antibody positivity to GAD65 (n = 8) had shorter graft survival compared to negative islet autoantibody (GAD65/IA2) subjects (n = 21; P = 0.016). Time of graft survival did not differ in subjects with single antibody positivity to IA2. The proportion of insulin independence attainment was similar irrespective of autoantibody status. The persistence of islet autoantibodies, as markers of islet autoimmunity, may represent an underappreciated contributing factor to the failure of transplanted β cells. Whether induction with T-cell depletion may lead to improved graft survival, independent of islet autoantibody status, could not be evaluated in our cohort. Larger prospective studies are needed to further address the role of islet autoantibody status on islet graft survival.

Altered Expression of Vitamin D Metabolism Genes and Circulating MicroRNAs in PBMCs of Patients with Type 1 Diabetes: Their Association with Vitamin D Status and Ongoing Islet Autoimmunity.

The immunomodulatory role of 1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) is exerted through its interaction with the vitamin D receptor (VDR) present on pancreatic and immune cells. While a deficiency in vitamin D has been linked to Type 1 Diabetes Mellitus (T1DM), the exact molecular mechanism driving this down-regulation in T1DM is yet to be fully understood. This study aimed to decipher differences in the expression of genes associated with vitamin D metabolism in T1DM patients and to ascertain if there is a correlation between serum 1,25(OH)2D3 levels and the expression of these genes. We also sought to understand the influence of specific microRNAs (miRNAs) on the expression of vitamin D metabolism genes in peripheral blood mononuclear cells (PBMCs) of T1DM patients. Furthermore, the study delved into the potential implications of altered vitamin D metabolism genes and miRNAs on autoimmune processes. Utilizing real-time PCR, we assessed the expression profiles of genes encoding for 1-hydroxylases (CYP27B1) and 24-hydroxylases (CYP24A1), as well as related miRNAs, in PBMCs from 30 T1DM patients and 23 healthy controls. ELISA tests facilitated the measurement of 1,25(OH)2D3, GAD65, and IA-2 levels. Our findings showcased downregulated CYP27B1 mRNA levels, while CYP24A1 expression remained stable compared to healthy subjects (CYP27B1, p = 0.0005; CYP24A1, p = 0.205, respectively). In T1DM patients, the levels of has-miR-216b-5p were found to be increased, while the levels of has-miR-21-5p were decreased in comparison to the control group. Notably, no correlation was identified between the expression of CYP27B1 in T1DM patients and the levels of has-miR-216b-5p, has-miR-21-5p, and 1,25(OH)2D3. A significant negative correlation was identified between CYP27B1 mRNA levels in PBMCs of T1DM and IA2, but not with GAD65. The study highlights there were reduced levels of both CYP27B1 mRNA and has-miR-21-5p, along with elevated levels of has-miR-216b-5p in the PBMCs of T1DM. However, the absence of a correlation between the expression of CYP27B1, levels of has-miR-216b-5p, and the status of 1,25(OH)2D3 suggests the possible existence of other regulatory mechanisms. Additionally, the inverse relationship between IA2 autoantibodies and CYP27B1 expression in T1DM patients indicates a potential connection between this gene and the autoimmune processes inherent in T1DM.

Relationship between β-Cell Autoantibodies and Their Combination with Anthropometric and Metabolic Components and Microvascular Complications in Latent Autoimmune Diabetes in Adults.

Our study aimed to investigate the relationship between three autoantibodies and their combination with anthropometric and metabolic components and microvascular complications in patients with latent autoimmune diabetes in adults (LADA). Our study included 189 LADA patients divided into four subgroups according to the autoantibodies present: glutamic acid decarboxylase autoantibodies (GADA) only; zinc transporter-8 autoantibodies (ZnT8A)+GADA; insulinoma-associated-2 autoantibodies (IA-2)+GADA; and ZnT8+IA-2+GADA. Compared to GADA positivity only, patients with ZnT8+GADA positivity and ZnT8+IA-2+GADA positivity had a shorter diabetes duration and lower body mass index (BMI); patients with ZnT8+GADA positivity were younger and showed an increase in glomerular filtration rate, while those with ZnT8+IA-2+GADA positivity had lower C-peptide and lower insulin resistance measured with HOMA2-IR. In a multiple regression analysis, ZnT8 positivity was associated with lower BMI (p = 0.0024), female sex (p = 0.0005), and shorter duration of disease (p = 0.0034), while IA-2 positivity was associated with lower C-peptide levels (p = 0.0034) and shorter diabetes duration (p = 0.02). No association between antibody positivity and microvascular complications of diabetes, including retinopathy, neuropathy, and microalbuminuria, as well as with variables of glucose control and β-cell function were found. The results of our study suggest that ZnT8 and IA-2 autoantibodies are present in a significant number of LADA patients and associated with clinical and metabolic characteristics resembling classic type 1 diabetes. Due to increased LADA prevalence, earlier identification of patients requiring frequent monitoring with the earlier intensification of insulin therapy might be of special clinical interest.

Study of the diagnostic efficiency of anti-ZnT8 autoantibodies for type 1 diabetes in pediatric patients.

Zinc transporter 8 autoantibodies (ZNt8A) are 1 of the 4 main autoantibodies used for the diagnosis of type 1 diabetes (T1D), with glutamic acid decarboxylase autoantibodies (GADA), islet antigen-2 autoantibodies (IA-2A), and insulin autoantibodies (IAA). The objective of this study is to evaluate the diagnostic efficiency of these autoantibodies for the diagnosis of T1D in pediatric patients. A retrospective analysis of patients under 16 years of age with suspected T1D was made between June 2020 and January 2021. A total of 80 patients were included in the study, with 1 sample per patient. Subjects were classified according to diagnosis. Of the subjects included in the study, 50 developed T1D. The diagnostic efficacy was IA-2A (cutoff ≥ 28 U/L) sensitivity 0.26 (95% CI: 0.14-0.38) and specificity 0.97 (95% CI: 0.79-1.0); GADA (cutoff ≥ 17 U/mL) sensitivity 0.40 (95% CI: 0.26-0.54) and specificity 0.87 (95% CI: 0.75-0.99); ZnT8A (cut off ≥ 15 U/L) sensitivity 0.62 (95% CI: 0.49-0.75) and specificity 0.97 (95% CI: 0.90-1.0). ZnT8A obtained the most significantly global diagnostic accuracy (0.75), and GADA with ZnT8A showed the highest correlation. The results obtained indicate a higher efficiency of anti-ZnT8 autoantibodies for the diagnosis of T1D in pediatric patients. Clinical efficiency of diabetic autoantibodies is method and assay dependent and influences combined diagnostic strategies.

1298-P: Independent Associations of GAD65, IA2, and ZnT8 Autoantibody (Ab) Positivity with C-Peptide (CPep) in a Diverse Cohort of Youth with Diabetes (DM)

The current DM classification does not fully enable precision medicine in DM due to heterogeneity between and within DM types, especially in racially diverse populations. Insulin deficiency (ID) is one of the most clinically actionable DM outcomes and, while its association with islet autoimmunity is known, the influence of Ab type and number after DM onset is uncertain. Thus, we assessed the effect of Ab characteristics on ID (measured as Cpep loss) in youth with established DM. We studied 151 youth with DM (median [IQR] age 15.0 [4.2] yrs, DM duration 5.4 [3.4] yrs), 61% female, 53% Hispanic and 17% non-Hispanic African American. We measured postprandial serum Cpep, glucose and Ab (GAD65, IA2 and ZnT8) and collected clinical/demographic data. Cpep loss was pre-specified as postprandial CPep &amp;lt;0.6 ng/ml. We found 0, 1, 2, or 3 +Ab in 34%, 22%, 31% and 13% of participants, respectively (Figure, left panel). A Breslow-Day statistic suggested homogeneity of the risk ratios across the 3 Ab types for CPep loss (p = 0.42), which were all larger than 1 (Figure, right panel). Cpep loss was significantly associated with ≥1 (vs 0) Ab+ (p &amp;lt; 0.0001) but not with single (vs multiple) Ab+ (p = 0.60). In sum, each of GAD65, IA2 and ZnT8 Ab are significantly associated with ID among diverse youth with DM. This suggests that models predicting ID post-onset should include each of GAD65, IA2 and ZnT8 Ab. Disclosure M.J.Redondo: None. R.A.Oram: Consultant; Janssen Research &amp; Development, LLC, Research Support; Randox R &amp; D. D.Dabelea: None. W.Hagopian: Research Support; Janssen Research &amp; Development, LLC, Provention Bio, Inc., Randox R &amp; D. Discover study group: n/a. K.K.Harrall: None. D.H.Glueck: None. M.Tosur: Advisory Panel; Provention Bio, Inc. S.Uysal: None. A.Muir: None. K.Vehik: None. T.M.Brusko: Consultant; Repertoire Immune Medicines, Quell Therapeutics, Research Support; Immunocore, Ltd., Adaptive Biotechnologies. M.A.Atkinson: None. Funding National Institutes of Health (R01DK124395)

Islet Autoantibodies to Pancreatic Insulin-Producing Beta Cells in Adolescent and Adults with Type 1 Diabetes Mellitus: A Cross-Sectional Study.

(1) Background: Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease caused by the destruction of pancreatic insulin-producing beta cells. T1D is one of the most common endocrine and metabolic disorders occurring in children. Autoantibodies against pancreatic insulin-producing beta cells are important immunological and serological markers of T1D. Zinc transporter 8 autoantibody (ZnT8) is a recently identified autoantibody in T1D; however, no data on ZnT8 autoantibody in the Saudi Arabian population have been reported. Thus, we aimed to investigate the prevalence of islet autoantibodies (IA-2 and ZnT8) in adolescents and adults with T1D according to age and disease duration. (2) Methods: In total, 270 patients were enrolled in this cross-sectional study. After meeting the study's inclusion and exclusion criteria, 108 patients with T1D (50 men and 58 women) were assessed for T1D autoantibody levels. Serum ZnT8 and IA-2 autoantibodies were measured using commercial enzyme-linked immunosorbent assay kits. (3) Results: IA-2 and ZnT8 autoantibodies were present in 67.6% and 54.6% of patients with T1D, respectively. Autoantibody positivity was found in 79.6% of the patients with T1D. Both the IA-2 and ZnT8 autoantibodies were frequently observed in adolescents. The prevalence of IA-2 and ZnT8 autoantibodies in patients with a disease duration < 1 year was 100% and 62.5%, respectively, which declined with an increase in disease duration (p < 0.020). Logistic regression analysis revealed a significant relationship between age and autoantibodies (p < 0.004). (4) Conclusions: The prevalence of IA-2 and ZnT8 autoantibodies in the Saudi Arabian T1D population appears to be higher in adolescents. The current study also showed that the prevalence of autoantibodies decreased with disease duration and age. IA-2 and ZnT8 autoantibodies are important immunological and serological markers for T1D diagnosis in the Saudi Arabian population.

Abstract #1394296: The First Reported Case of Lorlatinib-Associated Diabetic Ketoacidosis

Lorlatinib is a third-generation tyrosine kinase inhibitor that inhibits anaplastic lymphoma kinase (ALK) and c-ros oncogene 1 (ROS1). Although 2-10% of patients with non-small cell lung cancer developed hyperglycemia in phase 2 and 3 studies of lorlatinib, only one case has subsequently reported hyperglycemia >500 mg/dL, and no cases of diabetic ketoacidosis (DKA) have been previously reported. Phase 1 trials in neuroblastoma are ongoing. A 34-year-old woman with ALK-mutated paraspinal neuroblastoma presented with DKA 14 months after initiation of lorlatinib. Prior to starting lorlatinib, her hemoglobin A1c had been 5.0% (n: < 5.7%). After 12 months of therapy, her A1c increased to 7.8%, prompting the initiation of metformin 500 mg daily. However, two months later she was admitted for DKA with a blood glucose of 591 mg/dL (n: 65-99 mg/dL), CO2 17 mmol/L (n: 20-30 mmol/L), anion gap 18 (n: 8-12), moderate serum ketones, and 3+ ketonuria. Her A1c was 14.8%, C-peptide was 1.2 ng/mL (n: 1.1-4.3 ng/mL), and her glutamic acid decarboxylase-65 and islet antigen-2 autoantibodies were negative. She was also found to be incidentally positive for COVID-19 but was asymptomatic without any oxygen requirement. The patient’s DKA was successfully treated with IV insulin infusion, and she was discharged after 3 days with insulin glargine 27 units twice daily and insulin aspart 16 units with meals. One month later, her hemoglobin A1c had improved to 9.4%, and the patient’s oncologist discontinued lorlatinib due to sustained remission of her neuroblastoma and her complication of DKA. After stopping lorlatinib, her blood glucose rapidly improved, and she self-discontinued all her insulin in the following 3 weeks. One month later, she was seen in endocrine clinic only taking metformin 500 mg twice daily with fasting and post-prandial blood glucose ranging 86-107 mg/dL. This is the first reported case of DKA associated with lorlatinib. This case highlights the importance of close glucose monitoring and the risk of severe hyperglycemia and DKA while on lorlatinib therapy. Discontinuation of lorlatinib results in rapid improvement of glycemic control, and glucose-lowering treatments should be promptly deescalated to avoid hypoglycemia.

Abstract #1401677: Pembrolizumab Induced Autoimmune Diabetes Mellitus

Immune checkpoint inhibitors (ICIs) are integral in the treatment of a myriad of malignancies. While ICIs have significantly improved outcomes and cancer survivorship, they have also been implicated in immune related adverse events (irAEs), particularly autoimmune endocrinopathies. Common ICI associated endocrine disorders include hypothyroidism, hyperthyroidism, and primary adrenal insufficiency but rarely diabetes mellitus (DM). ICI induced DM is defined as severe and persistent insulin deficiency after treatment with an ICI. Here, we present a rare case of pembrolizumab induced DM presenting with hyperglycemic hyperosmolar state (HHS). A 77-year-old male with a past medical history of prediabetes on no medical therapy and melanoma of the right upper extremity was admitted with progressive polydipsia, polyuria and acute encephalopathy. Notably, the patient completed two cycles of pembrolizumab two weeks prior to admission. Initial workup demonstrated a glucose of 837 mg/dL (65-99), anion gap of 10 (3-11), small amounts of serum acetone and beta hydroxybutyrate, and a serum osmolality of 369 mOsm/kg (279-295). Venous blood gas revealed a pH of 7.33 (7.31-7.41), pCO2 45 mmHg (41-51), HCO3 24 mEq/L (23-29). Objective data supported the diagnosis of HHS. Hemoglobin A1c prior to initiation of pembrolizumab was 6.1% (< 5.7%) and on admission was 9.1%. He improved with intravenous insulin and fluids. After transition to basal/bolus insulin the patient’s fasting glucose was 126 mg/dL (65-99) with a c-peptide level of 0.41 ng/mL (0.80-3.85), consistent with insulin insufficiency. Glutamic acid decarboxylase 65 autoantibodies were positive, while islet cell and IA-2 autoantibodies were negative. Pembrolizumab was discontinued after the diagnosis of ICI induced DM was established. Our case highlights the unique course of a patient with prediabetes on pembrolizumab who developed ICI induced DM. Pembrolizumab (anti PD-1 monoclonal antibody) can cause an abnormal cytotoxic T cell (CD8+ T cell) mediated beta cell destruction and development of ICI induced DM. ICI induced DM shares characteristics of Type 1 DM with positive autoantibodies and insulin insufficiency. Insulin deficiency often precipitates diabetic ketoacidosis which was not seen in our patient. Given low but detectable c-peptide levels, our patient was likely insulin insufficient and not yet insulin deficient. This case highlights the importance of closely monitoring patients on ICIs, especially those with a predisposition to DM. In patients receiving immunotherapy, early identification of adverse events and risk stratification is essential in reducing morbidity and providing comprehensive care.

Affinity purification of serum-derived anti-IA-2 autoantibodies in type 1 diabetes using a novel MBP-IA-2 fusion protein

Autoantibodies targeting epitopes contained within the intracellular domain (IC) of the protein phosphatase-like islet antigen 2 (IA-2) are a common marker of autoimmune type 1 diabetes (T1D), however the isolation of genuine, serum derived anti-IA-2 autoantibodies has proven challenging due to a lack of suitable bioassays. In the current study, an ELISA format was developed for affinity purification of human anti-IA-2ic autoantibodies utilizing a fusion protein (FP) incorporating maltose binding protein and the full-length IA-2IC domain. Using a T1D patient cohort validated for anti-IA-2ic autoantibodies by commercial ELISA, we demonstrate the MBP-IA-2ic FP ELISA detects serum anti-IA-2IC autoantibodies from 3 of 9 IA-2 positive patients. Further to this, a multi-plate MBP-IA-2ic FP ELISA protocol specifically affinity purifies IgG enriched for anti-IA-2ic autoantibodies. Interestingly, serum derived autoantibodies immobilised on the MBP-IA-2ic FP ELISA demonstrate increased Kappa light chain usage when compared to the respective total IgG derived from donor patients, suggesting a clonally restricted repertoire of anti-IA-2ic autoantigen specific B plasma cells is responsible for autoantibodies detect by the MBP-IA-2ic FP ELISA. This study is the first to demonstrate the generation of specific, genuine human derived anti-IA-2ic autoantibodies, thereby facilitating further investigation into the origin and functional significance of IA-2 autoantibodies in T1D.

Clinical signs of type 1 diabetes are associated with type 2 diabetes marker transcription factor 7-like 2 polymorphism.

We aimed to assess the distribution of transcription factor 7-like 2 gene TCF7L2 (rs7903146) polymorphism and to find possible associations between TCF7L2 and the characteristics of type 1 diabetes. We studied 190 newly diagnosed type 1 diabetes patients (median age 12.7 years, range 2.0-72.5) and 246 controls (median age 23.8 years, range 1.4-81.5) for TCF7L2 single nucleotide polymorphism. We determined anti-islet autoantibodies, random C-peptide levels, diabetes associated HLA DR/DQ haplotypes and genotypes in all patients. There were no differences in the distribution of TCF7L2 single nucleotide polymorphism between patients and controls. However, patients with in type 1 diabetes, after adjusting for age and sex, subjects carrying C allele were at risk for a C-peptide level lower than 0.5 nmol/L (OR 5.65 [95% CI: 1.14-27.92]) and for zinc transporter 8 autoantibody positivity (5.22 [1.34-20.24]). Participants without T allele were associated with a higher level of islet antigen-2 autoantibodies (3.51 [1.49-8.27]) and zinc transporter 8 autoantibodies (2.39 [1.14-4.99]). The connection of TCF7L2 polymorphism with zinc transporter 8 and islet antigen-2 autoantibodies and C-peptide levels in patients supports the viewpoint that TCF7L2 is associated with the clinical signs and autoimmune characteristics of type 1 diabetes. The mechanisms of the interaction between the TCF7L2 risk genotype and anti-islet autoantibodies need to be studied further.

Clinical features, biochemistry, and HLA-DRB1 status in youth-onset type 1 diabetes in Mali.

Limited information is available regarding youth-onset diabetes in Mali. We investigated demographic, clinical, biochemical, and genetic features in new diabetes cases in children and adolescents. The study was conducted at Hôpital du Mali in Bamako. A total of 132 recently-diagnosed cases <21 years were enrolled. Demographic characteristics, clinical information, biochemical parameters (blood glucose, HbA1c, C-peptide, glutamic acid decarboxylase-65 (GAD-65) and islet antigen-2 (IA2) autoantibodies) were assessed. DNA was genotyped for HLA-DRB1 using high-resolution genotyping technology. A total of 130 cases were clinically diagnosed as type 1 diabetes (T1D), one with type 2 diabetes (T2D), and one with secondary diabetes. A total of 66 (50.8%) T1D cases were males and 64 (49.2%) females, with a mean age at diagnosis of 13.8 ± 4.4 years (range 0.8-20.7 years) peak onset of 15 years. 58 (44.6%) presented in diabetic ketoacidosis; with 28 (21.5%) IA2 positive, 76 (58.5%) GAD-65 positive, and 15 (11.5%) positive for both autoantibodies. HLA was also genotyped in 195 controls without diabetes. HLA-DRB1 genotyping of controls and 98 T1D cases revealed that DRB1*03:01, DRB1*04:05, and DRB1*09:01 alleles were predisposing for T1D (odds ratios [ORs]: 2.82, 14.76, and 3.48, p-values: 9.68E-5, 2.26E-10, and 8.36E-4, respectively), while DRB1*15:03 was protective (OR=0.27; p-value=1.73E-3). No significant differences were observed between T1D cases with and without GAD-65 and IA2 autoantibodies. Interestingly, mean C-peptide was 3.6 ± 2.7ng/ml (1.2 ± 0.9nmol/L) in T1D cases at diagnosis. C-peptide values were higher than expected in those diagnosed as T1D and autoantibody rates lower than in European populations. It is quite possible that some cases have an atypical form of T1D, ketosis-prone T2D, or youth-onset T2D. This study will help guide assessment and individual management of Malian diabetes cases, potentially enabling healthier outcomes.

Abstract 71: Preserved beta cell function in long standing type 1 diabetes mellitus

Background: Maturity onset diabetes of young (MODY) may be misdiagnosed as type 1 or type 2 diabetes mellitus and there may be an overlap between MODY and type 1 diabetes. The presence of persistent endogenous insulin, after the “honey-moon period” has ended, should lead to evaluation of secondary causes of diabetes including MODY.Aim: To identify subjects with preserved beta cell function; utilizing urinary C-peptide/creatinine ratio (UCPCR) in those, who have been diagnosed and treated as Type 1 diabetes mellitus.Methodology: Hospital based cross sectional study, between February 2019 and February 2021 in 100 Subjects diagnosed as Type 1 DM for more than 3 years.Results: Mean age and duration of DM 14.17 years and 5.3years respectively. Among 18 who had family history of D.M, 7 subjects had 3 generation involvement. GAD antibodies (68%) were more prevalent compared to IA 2 antibodies (56%). 49% had presence of both Anti GAD and IA2 auto antibodies. Mean UCPCR was 0.17. UCPCR >0.2 (suggestive of preserved endogenous insulin secretion) was present in 8 subjects among study population. Among these 8 subjects, 4 subjects had history of DKA episodes, 3 subjects had family history of D.M. 3 subjects did not have either of the auto antibodies. Compared to UCPCR <0.2, subjects with UCPCR >0.2 had statistically significant lower Hba1c (p=0.005), high UCPCR values (p=0.001), high MODY probability scores (p=0.004).Conclusions: UCPCR can be used as a screening tool to identify cases who need further evaluation for secondary causes, including genetic testing for MODY.

Automation of a multiplex agglutination-PCR (ADAP) type 1 diabetes (T1D) assay for the rapid analysis of islet autoantibodies.

Screening for islet autoantibody markers to identify individuals who are at high risk for developing type 1 diabetes (T1D), often years in advance of clinical symptoms, is both a challenge and a necessity. Identifying high-risk individuals not only reduces hospitalization and rates of life-threatening diabetes ketoacidosis (DKA), but also directs enrollment into prevention trials that require patients who are in the early stages of disease. Here we describe an automated high-throughput multiplex islet autoantibody assay that integrates antibody detection by agglutination-PCR (ADAP) chemistry on the Hamilton Microlab STAR liquid handling platform. The automated system features on-deck thermal cycling and plate sealing to minimize the level of human intervention. The automated multiplex ADAP T1D assay performed similarly to that of manual methods using two distinct cohorts of clinical specimens obtained from the Lucile Packard Children's Hospital at Stanford University and the 2018 Islet Autoantibody Standardization Program (IASP). Notably, the automated assay requires only 4 μL of serum sample for the simultaneous analysis of GAD, IA-2 and insulin autoantibodies. Up to 96 samples may be processed in as little as 3 hours, and the only user intervention required is to transfer a final sealed 96-well plate containing PCR amplicons onto a quantitative PCR (RT-qPCR) instrument for quantification. The automated system is particularly well suited for large-scale analysis of islet autoantibodies in a reproducible, timely, and cost-effective manner.

Differential HLA Association of GAD65 and IA2 Autoantibodies in North Indian Type 1 Diabetes Patients.

The human leucocyte antigen (HLA) association with type 1 diabetes (T1D) is well known but there are limited studies investigating the association between β-cell autoantibodies and HLA genes. We evaluated the prevalence of GAD65 and IA-2 autoantibodies (GADA and IA2A) in 252 T1D patients from North India and investigated the genetic association of GADA and IA2A with HLA class I and class II genes/haplotypes. GADA and IA2A were detected in 50.79% and 15.87% of T1D patients, respectively, while only 8.73% had both GADA and IA2A. HLA-DRB1∗03 was observed to be significantly higher in GADA+ T1D patients as compared to GADA– (91.41% vs. 66.13%, Bonferroni-corrected P (Pc) = 1.11 × 10−5; OR = 5.45; 95% CI: 2.67-11.08). Similarly, HLA-DQB1∗02 was found to be significantly increased in GADA+ patients (94.53%, Pc = 2.19 × 10−5; OR = 6.27; 95% CI: 2.7-14.49) as compared to GADA– (73.39%). The frequencies of HLA-DRB1∗04 and DQB1∗03 were increased in IA2A+ patients (45.0% and 52.5%, respectively) as compared to that in IA2A– (25.94% and 33.96%, respectively). Further, the frequency of DRB1∗03-DQB1∗02 haplotype was found to be significantly increased in GADA+ T1D patients as compared to GADA- (60.55% vs. 41.94%, P = 3.94 × 10−5; OR = 2.13; 95%CI = 1.49-3.03). Similarly, HLA-DRB1∗04-DQB1∗03 haplotype was found to be significantly increased in IA2A+ T1D patients compared to IA2A– patients (22.5% vs. 12.97%; P = 0.041; OR = 1.95; 95%CI = 1.08-3.52). None of the HLA class I genes (HLA-A, B, and Cw) was found to be associated with GADA or IA2A in people with T1D. Our findings suggest that HLA-DRB1∗03/DQB1∗02 and HLA-DRB1∗04/DQB1∗03 might play an important role in the development of GADA and IA2A, respectively.

Persistence of islet autoantibodies after diagnosis in type 1 diabetes.

The presence of islet autoantibodies remains a reliable biomarker to identify individuals at high risk of developing type 1 diabetes. As such, these autoantibodies play a pivotal role in understanding the prodrome of diabetes and selecting individuals for both prevention and intervention clinical trials. Over the last few decades, studies have sought to investigate autoantibody prevalence after diabetes onset to better understand ongoing islet autoimmunity; however, many findings are contradictory, and little is known about factors that may influence autoantibody persistence. Generally, glutamate decarboxylase autoantibodies (GADAs) are the most prevalent autoantibodies after diagnosis, particularly in adults, whilst zinc transporter 8 autoantibodies (ZnT8A) prevalence declines more rapidly. However, when studies with islet autoantibody data at diagnosis are considered, it becomes clear that overall islet antigen-2 autoantibodies (IA-2A) tend to persist for longer than GADA or ZnT8A. In this review, we assess the major studies that have contributed to our understanding of autoantibody persistence after diabetes onset and what factors affect this. Islet autoantibodies may provide biomarkers for long-term β-cell function and insights into how to prevent ongoing islet autoimmunity but larger studies collecting samples at and decades after diabetes onset are required to leverage the information they could provide.

Clinical features, epidemiology, autoantibody status, HLA haplotypes and genetic mechanisms of type 1 diabetes mellitus among children in Qatar

To describe the clinical features, epidemiology, autoantibody status, HLA haplotypes and genetic mechanisms of type 1 diabetes mellitus (T1DM). Patients (0–18 years) with diabetes were recruited. Clinical data was collected, autoantibodies and c-peptide were measured. Whole Genome Sequencing was performed. Genomic data analysis was compared with the known genes linked with T1DM and HLA alleles were studied. 1096 patients had one or more antibody positivity. The incidence of T1DM in 2020 was 38.05 per 100,000 children and prevalence was 249.73. GADA was the most common autoantibody followed by IAA. Variants in GSTCD, SKAP2, SLC9B1, BANK1 were most prevalent. An association of HLA haplotypes DQA1*03:01:01G (OR = 2.46, p value = 0.011) and DQB1*03:02:01G (OR = 2.43, p value = 0.022) was identified. The incidence of T1DM in Qatar is the fourth highest in the world, IA2 autoantibody was the most specific with some patients only having ZnT8 or IA2 autoantibodies thus underlining the necessity of profiling all 4 autoantibodies. The genes associated with T1DM in the Arab population were different from those that are common in the Caucasian population. HLA-DQ was enriched in the Qatari patients suggesting that it can be considered a major risk factor at an early age.

Zinc transporter 8 (ZnT8) autoantibody prevalence in black South African participants with type 1 diabetes

BackgroundAutoantibodies to β-cell specific antigens are markers of type 1 diabetes. The most recently identified autoantibodies are targeted to the zinc transporter 8 (ZnT8) protein located in the membrane of β-cell insulin secretory granules. The prevalence of ZnT8 autoantibodies in newly diagnosed participants with type 1 diabetes has been found to range from 33 to 80 %. Due to the lack of data on the immunological aetiology of type 1 diabetes in African populations, this study aimed to determine the prevalence of ZnT8 autoantibodies in black South Africans with type 1 diabetes and whether ZnT8 autoantibody positivity was associated with age at diagnosis and disease duration.MethodsParticipants with type 1 diabetes and controls were recruited from the greater Johannesburg area, South Africa. Positivity for ZnT8, GAD65 and IA2 autoantibodies was determined by ELISA.ResultsParticipants with type 1 diabetes (n = 183) and controls (n = 49) were matched for age (29.1 ± 9.53 vs. 27.3 ± 7.29, respectively; p = 0.248). The mean age at diagnosis for participants with type 1 diabetes was 20.8 ± 8.46 years. The prevalence of ZnT8 autoantibody positivity was 17.5 % (32 of 183) in participants with type 1 diabetes with a median disease duration of 7.00 [2.00; 11.0] years. ZnT8 autoantibody prevalence in newly diagnosed participants (< 1 year duration) was 27.3 % (6 of 22). Logistic regression analysis found an association between ZnT8 autoantibody positivity and shorter disease duration (OR: 0.9 (0.81-1.00); p = 0.042). In addition, ZnT8 autoantibody positivity was significantly associated with an increased chance of being GAD65 (OR: 3.37 (1.10–10.3)) and IA2 (OR: 8.63 (2.82–26.4)) autoantibody positive. Multiple regression analysis found no association between ZnT8 autoantibody positivity and age at diagnosis. However, the presence of ≥ 2 autoantibodies was associated with a younger age at diagnosis of type 1 diabetes when compared to participants with ≤ 1 autoantibody (B = -5.270; p = 0.002).ConclusionsThe presence of ZnT8 autoantibodies was not related to a younger age at diagnosis in black South African patients with type 1 diabetes. However, the greater the numbers of autoantibodies present in an individual the earlier the age at diagnosis. ZnT8 autoantibodies decline with disease duration in the black South African population.

Autoantibodies in Moroccan patients with type 1 diabetes: Which one to choose?

Background. Immunological investigations are intend-ed for diagnosing T1D in atypical clinical presentation, also exploring the predisposition to T1D in a context of multiple autoimmune disorders or among the siblings of a patient with type 1 diabetes. While the diagnosing or the screening of T1D using five antibodies presents high expenses especially in emerging countries, it is for interest to determine their prevalence in order to choose the most frequent and most relevant. The aim of our study is to determine the prevalence of antibodies in Moroccan population. Methods. We investigated 62 T1D patients, the prevalence of autoantibodies was 74% for glutamic acid decarboxylase 65 autoantibody (GADA), 46% for insulinoma-associated protein 2 autoantibody (IA2A), and 3% for islet cell antibodies (ICA). GADA and/or IA2A were reported in all patients (100%). The GADA frequency was neither associated with the duration of diabetes nor the age of patients. Results. Finally, GADAs are by far the best markers for T1D, IA2As complements GADAs and increases the diagnostic sensitivity for detection of pancreatic autoimmunity and ICA should be abandoned because of its low prevalence.