Characterization of patients with diabetes who were incidentally found to be glutamic acid decarboxylase autoantibody-positive by bridging-type enzyme-linked immunosorbent assay

Trends in endogenous insulin secretion capacity and anti-islet autoantibody titers in two childhood-onset slowly progressive insulin-dependent diabetes mellitus cases

Slowly progressive insulin-dependent (type 1) diabetes mellitus (SPIDDM) is a subtype of type 1 diabetes. Although SPIDDM is not rare among Japanese children, there are few reports on endogenous insulin secretory capacity and anti-pancreatic islet autoantibodies in pediatric SPIDDM. We followed the trends in endogenous insulin secretory capacity and anti-pancreatic islet autoantibody titers in two pediatric SPIDDM cases over several years. Case 1 developed insulin deficiency eight months after diabetes diagnosis; as her insulinoma-associated antibody test result was positive, insulin therapy was initiated. Fourteen months after the diagnosis, she tested positive for glutamic acid decarboxylase autoantibodies (GADA) and was diagnosed with SPIDDM. Case 2 was mildly positive for GADA at the onset of diabetes, but became a high titer during the course of the disease. Fourteen months after the diagnosis of diabetes, he became mildly insulin deficient, and insulin therapy was initiated. However, his insulin secretory capacity was preserved for 60 mo after the onset. SPIDDM is generally indistinguishable from type 2 diabetes at diagnosis; therefore, repeated evaluation of the insulin secretory capacity and anti-islet autoantibodies facilitates early diagnosis and appropriate treatment, especially in nonobese children with type 2 diabetes.

Improving diagnostic accuracy of 3 Screen ICA ELISA kit in the identification of Japanese type 1 diabetes

AIM/INTRODUCTION

This study aimed to investigate the clinical utility of 3 Screen ICA ELISA in identifying immune-mediated type 1 diabetes in Japanese subjects.

METHODS

We compared the positivity of 3 Screen ICA were compared with autoantibodies against GAD, IA-2, and ZnT8 in 638 patients with type 1 diabetes and 159 healthy control subjects.

RESULTS

With a cut-off value of 20.0 index, 67.4% of acute-onset type 1 diabetic patients, 71.8% of slowly progressive type 1 diabetic (SPIDDM) patients, and none of the fulminant type 1 diabetic patients showed 3 Screen ICA levels above this threshold. The prevalence of 3 Screen ICA was 14.2% higher in acute-onset type 1 diabetes and 1.6% higher in SPIDDM than in GADA. 3 Screen ICA-positive cases were found in 4.8% of cases of individual autoantibody-negative acute-onset type 1 diabetes and 3.8% of SPIDDM, indicating improved diagnostic sensitivity with the 3 Screen ICA. Among individual autoantibody-negative patients, the sum of each autoantibody level was significantly lower in fulminant type 1 diabetes than in acute onset type 1 diabetes and in SPIDDM (P < 0.0001). Additionally, 84.2% of patients negative for individual autoantibodies but positive for 3 Screen ICA had a sum of individual autoantibody levels of ≥4.7 U/mL. Furthermore, 3 Screen ICA levels were significantly higher in patients with type 1 diabetes with other autoimmune diseases than in those without (P < 0.0001).

CONCLUSION

Our findings suggest that the 3 Screen ICA ELISA may be a valuable screening tool for Japanese patients with type 1 diabetes, potentially increasing the diagnostic sensitivity and accuracy beyond the existing GADA, IA-2A, and ZnT8A tests.

Adult-onset autoimmune diabetes

Adult-onset autoimmune (AOA) diabetes pathophysiology starts with immune changes, followed by dysglycaemia and overt disease. AOA diabetes can occur as classic type 1 diabetes when associated with severe loss of insulin secretion. More frequently, it is diagnosed as latent autoimmune diabetes in adults, a slowly progressing form with late onset, a long period not requiring insulin, and it is often misdiagnosed as type 2 diabetes. As its clinical presentation varies remarkably and immune markers often lack specificity, it is challenging to classify each case ad hoc, especially when insulin treatment is not required at diagnosis. Proper care of AOA diabetes aims to prevent complications and to improve quality of life and life expectancy. To achieve these goals, attention should be paid to lifestyle factors, with the aid of pharmacological therapies properly tailored to each individual clinical setting. Given the heterogeneity of the disease, choosing the right therapy for AOA diabetes is challenging. Most of the trials testing disease-modifying therapies for autoimmune diabetes are conducted in people with childhood onset, whereas non-insulin diabetes therapies have mostly been studied in the larger population with type 2 diabetes. More randomized controlled trials of therapeutic agents in AOA diabetes are needed.