The control of severe hypoglycemic symptoms in patients with insulin‐secreting islet tumors (insulinoma) of the pancreas is an important aspect of management. A series of 24 patients with insulinomas whose ages ranged from 5 months to 73 years seen at one center over a period of 17 years is described. The presenting symptoms and the effect of these on their lifestyles are discussed. Diazoxide has been used to control hypoglycemic symptoms in 18 of the 24 patients. Fourteen patients have received diazoxide for varying periods of time prior to successful surgery and 4 have received long‐term therapy. Three of these patients are highlighted to show various aspects of benefit and problems from the use of diazoxide. The mean dosage of diazoxide was 400 mg/day and the mean duration of therapy was 10 months. The control of symptoms was good in 8, fair in 6, and poor in 4. The main side effects observed were hirsutism (56%), ankle edema (50%), weight gain (38%), and nausea (11%). These side effects were well tolerated and the benefits of therapy were felt to outweigh disadvantages. Side effects only necessitated discontinuation of diazoxide in 1 patient who developed a severe hypersensitivity reaction. Our results show that diazoxide has a role to play in the management of patients with insulinoma during preoperative tumor localization and can also be used when surgery is contraindicated or when laparotomy is unsuccessful.