A case of insulin-secreting tumor successfully treated with diazoxide

A 72-year-old patient was referred to our hospital because of a hypoglycemic crisis possibly due to an insulin secreting-tumor. Although its localization was assumed to be at the head of the pancreas as assessed by transhepatic venography with sampling, no mass lesion was detected by selective angiography, ultrasound, computerized axial tomography, magnetic resonance imaging and 67Ga-citrate scan. The patient was treated with diazoxide, because of poor localization and his age, insulin secretion was improved after both 30 and 60 min in the 75 g oral glucose tolerance test. The total amount of urinary C-peptide excretion decreased from 70.8 to 29.2 mcg/day. Thereafter, no hypoglycemic symptoms were observed during his admission. No side effects except mild liver damage were observed.