INSULINOMA IN A PATIENT WITH NIDDM

OBJECTIVE - To confirm insulinoma as the cause of hypoglycemia in a pa tient with NIDDM and determine the frequency of the co-occurrence of t hese two conditions. RESEARCH DESIGN AND METHODS - The patient underwe nt an in-hospital prolonged fast (less-than-or-equal-to 72 h), accordi ng to standard protocol, and an ultrasound examination of the pancreas . All cases of histologically confirmed insulinoma at this institution over the period of 1927-1992 were reviewed to determine the prevalenc e of pre-existent diabetes mellitus. RESULTS - After 10 h of fasting, plasma glucose was low (1.89 mM); plasma insulin (258 pM) and C-peptid e (1.39 nM) were elevated in the absence of sulfonylurea in the plasma . An insulinoma detected by ultrasonography was removed surgically wit h subsequent reoccurrence of insulin-requiring diabetes. Among 313 cas es of insulinoma confirmed at this institution, this patient is the on ly one with pre-existent diabetes mellitus. CONCLUSIONS - insulinoma o ccurs extraordinarily rarely in patients with pre-existing NIDDM.