The differential diagnosis of a patient with an insulin-secreting tumor of the pancreas usually is not difficult in the presence of repeated low fasting blood sugar values, aided by other standard laboratory tests. However, when borderline fasting blood sugar values are encountered, difficulty may arise in distinguishing insuloma from other hypoglycemic conditions, particularly those of diabetic and functional origins.
It is the purpose of this report to describe the response of proved insuloma patients to the recently introduced L-leucine * sensitivity14 and tolbutamide6 tests, which under these latter conditions may serve as useful diagnostic adjuncts.
The results of this study lend support to the thesis that a diagnosis of an insulinsecreting tumor is tenable when, in the absence of hepatic, pituitary, or adrenal insufficiency, a positive leucine and tolbutamide response is elicited.
Subjects and Methods
The following groups of patients were used in this study: (1) 3 patients with