A case of fulminant type 1 diabetes with transiently positive anti-GAD antibodies

Abstract

A subtype of idiopathic type 1 diabetes with a rapid onset and no diabetes-related antibodies has been recently advocated as non-autoimmune fulminant type 1 diabetes. However, it is not definite yet that this subtype is always caused by non-autoimmune mechanism. A 48-year-old man was admitted to our hospital because of high plasma glucose and renal insufficiency. Laboratory findings were as follows: plasma glucose 1052 mg/dL, urinary ketone bodies (±), arterial blood pH 7.44, bicarbonate 23.8 mmol/L, base excess 0.3 mmol/L, plasma osmolality 342 mOsm/L, serum creatinine 2.1 mg/dL, blood urea nitrogen 69.7 mg/dL, and serum creatine kinase 1024 IU/L, giving a diagnosis of acute renal failure secondary to rhabdomyolysis associated with diabetes. Urinary C-peptide reactivity was 4.7 μg/day. The level of HbA1c was 7.0%, not so high as compared to that of plasma glucose, indicating an aggravation of diabetes within the recent short period. Antibodies to islet cell antigen, 1A-2 and insulin were negative, while those to glutamic acid decarboxylase (GAD) were positive at 13.1 U/mL, which were negative half a year and two years and a half later. Serum amylase level was within normal range at admission, increased to 380 IU/L and normalized in 4 to 5 weeks as serum creatinine lowered. These data are compatible to the diagnosis of fulminant type 1 diabetes. However, the present case is different from others in positive antibodies to GAD at admission that turned to be negative subsequently. Considering our results and others together, further investigations are necessary to clarify whether all cases of fulminant type 1 diabetes are non-autoimmune or some of them are caused by autoimmune mechanism.