A patient with rapid metabolic deterioration mimicking the onset of fulminant type 1 diabetes during treatment for autoimmune type 1 diabetes

A 55-year-old man, recognized as having impaired glucose tolerance three years earlier, presented with an HbA1c (JDS) of 11 %. Sulfonylurea plus α-glucosidase inhioitor treatment was started, resulting in a decrease in HbA1c to 6.6 % two months later. However, since GAD (glutamic acid decarboxylase) antibodies were positive, he was diagnosed as having autoimmune type 1 diabetes and his treatment regimen was switched to intensive insulin therapy. Ten U/day of insulin effectively controlled his metabolic state for about 40 days: preprandial SMBG (self-monitoring of blood glucose) levels were approximately 100 mg/dl. However, despite the absence of known triggers including dietary conditions, he developed sudden abdominal fullness, thirst and polyuria and preprandial SMBG levels rose rapidly to more than 300 mg/dl for ten days. On admission, though he had already started insulin therapy, clinical findings met the diagnostic criteria for fulminant type 1 diabetes. At the time of discharge, 36 U/day of insulin were needed for glycemic control. In this case, SMBG enabled us to demonstrate rapid metabolic deterioration, mimicking the onset of fulminant type 1 diabetes, despite good control of autoimmune type 1 diabetes.