Emergence of anti-islet autoantibodies in Japanese patients with type 1 diabetes

Enzyme-linked immunosorbent assay of 3 Screen Islet Cell Autoantibody in patients with autoimmune thyroid disease

BACKGROUND

In recent years, the emergence of multiplex technology that can simultaneously measure multiple anti-islet autoantibodies has become particularly valuable for the staging and early diagnosis of immune-mediated type 1 diabetes (T1D). While it has been established that 20%-30% of T1D patients suffer from autoimmune thyroid disease (AITD), there is limited available data regarding the presence of anti-islet autoantibodies in AITD patients. Among commercially available anti-islet autoantibodies, glutamic acid decarboxylase 65 autoantibodies (GADAs) are often the first marker measured in general clinical practice.

AIM

To investigate the frequency of anti-islet autoantibodies in AITD patients.

METHODS

Our study involved four hundred ninety-five AITD patients, categorized into three distinct groups: AITD with T1D (n = 18), AITD with phenotypic type 2 diabetes (T2D) (n = 81), and AITD without diabetes (n = 396), and the enzyme-linked immunosorbent assay (ELISA) was employed to determine the frequencies of 3 Screen Islet Cell Autoantibody (3 Screen ICA), GADA, insulinoma-associated antigen-2 autoantibodies (IA-2As), and zinc transporter 8 autoantibodies (ZnT8As) within these groups.

RESULTS

The frequency of 3 Screen ICA in AITD patients with T1D, T2D, and those without diabetes were 88.9%, 6.2%, and 5.1%, respectively, with no significant difference seen between the latter two groups. Notably, the frequency of 3 Screen ICA was 11.1% higher in AITD patients with T1D, 1.3% higher in AITD patients with T2D, and 1.1% higher in AITD patients without diabetes compared to GADA, respectively. Furthermore, 12.5%, 20.0%, and 20.0% of the 3 Screen ICA-positive patients were negative for GADA. Additionally, 1.3% of the AITD patients who tested negative for 3 Screen ICA in both the AITD with T2D and non-diabetic AITD groups were found to be positive for individual autoantibodies. Among the 3 Screen ICA-positive patients, there was a significantly higher proportion of individuals with multiple autoantibodies in AITD patients with T1D compared to those without diabetes (37.5% vs 5.0%, P < 0.05). However, this proportion was similar to that in AITD patients with T2D (20.0%). Nevertheless, there was no significant difference in 3 Screen ICA titers between AITD patients with T1D and those without diabetes (436.8 ± 66.4 vs 308.1 ± 66.4 index). Additionally, no significant difference in 3 Screen ICA titers was observed between Graves' disease and Hashimoto's thyroiditis in any of the groups.

CONCLUSION

Our findings reveal that some AITD patients without diabetes exhibit 3 Screen ICA titers comparable to those in AITD patients with T1D. Thus, 3 Screen ICA outperforms GADA in identifying latent anti-islet autoantibody-positive individuals among AITD patients.

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.

Type 1 Diabetes Mellitus Diagnosed during Follow-up of Gestational Diabetes Mellitus in the Early Postpartum Period

A 27-year-old woman with a history of gestational diabetes mellitus (GDM) developed type 1 diabetes mellitus (T1D) in the early postpartum period. Women with a history of GDM are at an increased risk of developing T1D, which is rarer than type 2 diabetes mellitus. A postpartum follow-up 75-g oral glucose tolerance test and the measurement of glutamic acid decarboxylase autoantibodies aided in the early detection of T1D in this patient. Careful attention should be paid to women with a history of GDM who exhibit clinical features suggestive of future development of T1D.