Zinc transporter 8 autoantibodies complement glutamic acid decarboxylase and insulinoma-associated antigen-2 autoantibodies in the identification and characterization of Japanese type 1 diabetes

Analysis of thyroid autoantibodies and the risk of insulin depletion after the clinical onset of acute-onset type 1 diabetes in Japanese patients: the TIDE-J study

Introduction

Type 1 diabetes is often accompanied by autoimmune thyroid disease. We aimed to investigate the clinical characteristics of Japanese patients with acute-onset type 1 diabetes and thyroid autoantibodies, focusing on decreased endogenous insulin secretion.

Materials and methods

We examined 80 patients with acute-onset type 1 diabetes, classifying them into two groups with and without thyroid autoantibodies and compared the clinical characteristics of the two groups. A fasting serum C-peptide immunoreactivity (CPR) of less than 0.1 ng/mL was defined as insulin depletion.

Results

In patients with thyroid autoantibodies, the median fasting serum CPR levels at the fourth year after the onset of type 1 diabetes were significantly lower than in those without thyroid autoantibodies (p = 0.02). The cumulative incidence of insulin depletion at 5 years of duration after diagnosis of type 1 diabetes was significantly higher in thyroid autoantibody-positive group than in thyroid autoantibody-negative group (p = 0.01). In the Cox proportional models adjusted for selected baseline factors (age, sex, and BMI), the presence of thyroid autoantibodies did not increase the risk of insulin depletion within 5 years after the onset. However, in bivariate Cox proportional hazards models that investigated the association between thyroid autoantibodies and each baseline factor, the presence of thyroid autoantibodies significantly increased the risk of insulin depletion.

Conclusions

Our study showed that Japanese patients with acute-onset type 1 diabetes and positive for thyroid autoantibodies had a higher risk of insulin deficiency within 5 years after the onset than those without thyroid autoantibodies.

Microbial mimics supersize the pathogenic self-response

Microbial mimicry, the process in which a microbial antigen elicits an immune response and breaks tolerance to a structurally related self-antigen, has long been proposed as a mechanism in autoimmunity. In this issue of the JCI, Dolton et al. extend this paradigm by demonstrating that a naturally processed peptide from Klebsiella oxytoca acts as a superagonist for autoreactive T cells in type 1 diabetes (T1D). Reframing microbial mimics as superagonists that are thousands of times better at binding disease-associated autoreactive T cell receptors than self-peptides serves to narrow the search space for relevant sequences in the vast microbial proteome. Moreover, the identified superagonists have implications for the intervention and personalized monitoring of T1D that may carry over to other autoimmune diseases with microbial mimicry.

Clinical and Biochemical Features Used to Classify Type-1 and Type-2 Diabetes: A Scoping Review

The classification of diabetes into type-1 (T1D) and type-2 (T2D) is a critical step in tailoring effective treatment strategies. This distinction relies on a nuanced evaluation of clinical and biochemical features. While age at diagnosis, autoimmune markers, and beta-cell function are among the crucial clinical parameters, biochemical indicators like C-peptide levels and antibody analyses play a pivotal role. This review comprehensively examines the utility of these features in accurately categorizing individuals into T1D and T2D subtypes, providing valuable insights for clinical practice.

This scoping review systematically analyses 32 studies aimed at classifying T1D and T2D using various predictor variables. Clinical parameters including family history of diabetes, age at diagnosis, sex, history of insulin use, percent desirable weight or body mass index, waist, and blood pressure emerge as pivotal diagnostic tools. C-peptide measures, encompassing urinary C-peptide to creatinine ratio (UCPCR), and serum fasting and stimulated C-peptide levels further augment classification. Biochemical markers beyond C-peptide, such as serum level of adiponectin, triglycerides (TG), high-density lipoprotein–cholesterol (HDL-C), low-density lipoprotein (LDL-C), Total cholesterol, fasting and postprandial plasma glucose, and glycated hemoglobin (HbA1c), provide supplementary information for classification. Ketonuria and postglucagon or meal-stimulated C-peptide measurements contribute to nuanced classification, particularly in insulin-treated populations. Antibody analyses, particularly presence of GAD65, Zinc Transporter, and IA2 antibodies, highlight the autoimmune nature of T1D. In conclusion, this scoping review underscores the importance of a comprehensive approach that integrates clinical, biochemical, and immunological markers in accurately differentiating between T1D and T2D in clinical practice.

Epidemiology and phenotypes of diabetes in children and adolescents in non-European-origin populations in or from Western Pacific region

BACKGROUND

Type 1 diabetes (T1D) incidence varies substantially between countries/ territories, with most studies indicating increasing incidence. In Western Pacific region (WPR), reported rates are much lower than European-origin populations. In contrast, there are reports of substantial numbers of young people with type 2 diabetes (T2D). A deeper understanding of T1D and T2D in the WPR may illuminate factors important in pathogenesis of these conditions. Furthermore, with varying resources and funding for diabetes treatment in this region, there is a need to more clearly determine the current burden of disease and also any gaps in knowledge.

AIM

To compile and summarise published epidemiologic and phenotypic data on childhood diabetes in non-European populations in and from WPR.

METHODS

Research articles were systematically searched from PubMed (MEDLINE), Embase, Cochrane library, and gray literature. Primary outcome measures were incidence and prevalence, with secondary measures including phenotypic descriptions of diabetes, including diabetes type categorization, presence of diabetic ketoacidosis (DKA) at onset, autoantibody positivity, C-peptide levels, and human leucocyte antigen phenotype. Extracted data were collected using a customized template. Three hundred and thirty relevant records were identified from 16 countries/territories, with analysis conducted on 265 (80.3%) records published from the year 2000.

RESULTS

T1D incidence ranged from < 1-7.3/100000 individuals/year, rates were highest in emigrant/ mixed populations and lowest in South-East Asia, with most countries/territories (71.4%) having no data since 1999. Incidence was increasing in all six countries/territories with data (annual increases 0.5%-14.2%, highest in China). Peak age-of-onset was 10-14 years, with a female case excess. Rate of DKA at onset varied from 19.3%-70%. Pancreatic autoantibodies at diagnosis were similar to European-origin populations, with glutamic acid decarboxylase-65 autoantibody frequency of 44.1%-64.5%, insulinoma-associated 2 autoantibody 43.5%-70.7%, and zinc transporter-8 autoantibody frequency 54.3% (one study). Fulminant T1D also occurs. T2D was not uncommon, with incidence in Japan and one Chinese study exceeding T1D rates. Monogenic forms also occurred in a number of countries.

CONCLUSION

T1D is less common, but generally has a classic phenotype. Some countries/ territories have rapidly increasing incidence. T2D is relatively common. Registries and studies are needed to fill many information gaps.

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

BACKGROUND

Autoantibodies 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.

METHODS

Participants 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.

RESULTS

Participants 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).

CONCLUSIONS

The 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.

Different interaction of onset age and duration of type 1 diabetes on the dynamics of autoantibodies to insulinoma-associated antigen-2 and zinc transporter 8

Aims/Introduction

This study aimed to investigate the dynamics associated with autoantibodies to insulinoma‐associated antigen‐2 (IA‐2A) and zinc transporter 8 (ZnT8A) relating to the onset age and disease duration in patients with type 1 diabetes.

Methods

Using bridging‐type enzyme‐linked immunosorbent assay, IA‐2A, ZnT8A and glutamic acid decarboxylase autoantibodies were evaluated in 269 patients with type 1 diabetes (median onset age 18.2 years, range 0.8–86 years; median diabetes duration 7 years, range 0–58 years). We then compared the prevalence of these autoantibodies among the different age groups, along with the duration of diabetes using the Cochran–Armitage trend test and multivariate logistic regression analysis.

Results

The prevalence of IA‐2A, ZnT8A and glutamic acid decarboxylase autoantibodies in patients with duration of ≤3 years was 41.1, 36.7 and 72.2%, respectively, with 80.0% expressing one or more of these autoantibodies. This prevalence declined according to the disease duration (P < 0.005). Both IA‐2A and ZnT8A were more frequently observed in younger patients, whereas glutamic acid decarboxylase autoantibodies was more common in older patients. Multivariate logistic regression analysis showed that there was a significant interaction between the onset age and duration of diabetes in patients diagnosed when aged ≤10 years regarding all anti‐islet autoantibodies (P < 0.05). However, for patients diagnosed in the middle tertile (aged 11–30 years), the interaction was significant only for ZnT8A, and for those with late‐onset diabetes (aged ≥31 years) only for IA‐2A.

Conclusions

The current study showed that the rate of disappearance of anti‐islet autoantibodies is faster in patients aged ≤10 years, and that even though both proteins are localized in the insulin granule membrane, humoral autoimmunity to IA‐2 and ZnT8 differs according to the age of onset.