Positivity for islet cell autoantibodies in patients with monogenic diabetes is associated with later diabetes onset and higher HbA1c level

Aims Islet cell autoantibodies are associated with autoimmune insulitis and belong to the diagnostic criteria of Type 1 diabetes mellitus. However, growing evidence suggests that autoantibodies are present in other types of diabetes. Here, we focus on the autoantibody incidence in Czech patients with maturity‐onset diabetes of the young and analyse their functional relevance in terms of diabetes onset and control. Methods Autoantibodies against glutamic acid decarboxylase (GAD) 65 and protein tyrosine phosphatase islet antigen 2 (IA‐2) were measured in a cohort of 28 Czech patients with maturity‐onset diabetes of the young, all confirmed by genetic testing. Selected clinical data were correlated to the status and kinetics of autoantibodies. Results One quarter of patients with maturity‐onset diabetes of the young examined (7/28; 25%) was positive for GAD or IA‐2 autoantibodies. GAD autoantibodies were more prevalent (7/7) than IA‐2 autoantibodies (1/7). The incidence of autoantibodies did not correlate with human leukocyte antigen status. The patients who were positive for the autoantibodies developed diabetes later than those who were autoantibody‐negative, but had worse glycaemic control (increased HbA1c). Expression of autoantibodies decreased with any improvement of diabetes compensation. Only one patient did not correspond to the above and displayed signs of combined signs of maturity‐onset diabetes of the young and Type 1 diabetes. Conclusions The data suggest transient but highly prevalent islet cell autoantibody expression in Czech patients with maturity‐onset diabetes of the young. The autoantibodies were found in patients with delayed diabetes onset, and in times of insufficient diabetes control. As improvement of glycaemic control was associated with a decrease in levels of autoantibodies, their presence may reflect the kinetics of β‐cell destruction induced by causes other than autoimmune ones. What's new? Islet cell autoantibodies are present in a broad spectrum of patients with maturity‐onset diabetes of the young. Islet cell autoantibodies in maturity‐onset diabetes of the young are associated with delayed diabetes onset and poor glycaemic control. Transient kinetics of islet cell autoantibody expression in maturity‐onset diabetes of the young reflects changes in diabetes control (HbA1c level). Relevance of islet cell autoantibodies as a marker of exclusively autoimmune β‐cell destruction is questioned. Patients with maturity‐onset diabetes