Complete loss of insulin secretion capacity in type 1A diabetes patients during long‐term follow up

Aim/Introduction Patients with type 1 diabetes are classified into three subtypes in Japan: acute onset, fulminant and slowly progressive. Acute‐onset type 1 diabetes would be equivalent to type 1A diabetes, the typical type 1 diabetes in Western countries. The insulin secretion capacity in Japanese patients with long‐standing type 1A diabetes is unclear. The aim of the present study was to clarify the course of endogenous insulin secretion during long‐term follow up and the factors associated with residual insulin secretion in patients with acute‐onset type 1 diabetes (autoimmune). Materials and Methods We retrospectively investigated endogenous insulin secretion capacity in 71 patients who fulfilled the diagnostic criteria for acute‐onset type 1 diabetes (autoimmune) in Japan. To assess the residual insulin secretion capacity, we evaluated randomly measured C‐peptide levels and the results of glucagon stimulation test in 71 patients. Results In the first year of disease, the child‐ and adolescent‐onset patients had significantly more in residual insulin secretion than the adult‐onset patients (34 patients in total). C‐peptide levels declined more rapidly in patients whose age of onset was ≤18 years than in patients whose age of onset was ≥19 years. Endogenous insulin secretion capacity stimulated by glucagon was completely lost in almost all patients at >15 years after onset (61 patients in total). Conclusions Most patients with acute‐onset type 1 diabetes (autoimmune) completely lose their endogenous insulin secretion capacity during the disease duration in Japan. Age of onset might affect the course of insulin secretion.