Abstract
Disopyramide (Rythmodan ®) is a new antiarrhythmic agent with quinidine-like actions. We report a 56-yr-old diabetic woman in whom a hypoglycemic effect of this agent was proved.
The patient was admitted to our hospital complaining of visual disturbance due to fresh hemorrhage into the vitreous body of the right eye. On the 22nd hospital day, her electrocardiogram revealed ventricular extrasystoles. She was administered 300 mg/day of disopyramide and the ventricular extrasystoles disappeared. Prior to disopyramide therapy, the fasting blood glucose level was 215 mg/dl. On the 8th day after administration of the agent, while she was treated with 16 units of lente insulin and a 1400 Cal diabetic diet regimen, the fasting blood glucose level was 147 mg/dl and on the 14th day the fasting blood glucose level decreased to 85 mg/dl. From the following day, the dosage of lente insulin was reduced. Her blood glucose levels were controlled with 6 units of lente insulin. After the patient was discharged on the 67th hospital day. the blood glucose levels were not elevated. The fasting blood glucose level was 111 mg/dl. Since an electrocardiogram had revealed no ventricular extrasystoles, disopyramide was withdrawn. The blood glucose increased again to a level of 195 mg/dl even with 12 units of lente insulin. During this course, she received no other hypoglycemic agents and her body weight and renal function tests revealed no changes. A 50 g OGTT during treatment with disopyramide, demonstrated an improvement of glucose intolerance compared to that prior to disopyramide therapy and showed a normal response of C-peptide immunoreactivity. After withdrawal of the agent, a 50 g OGTT revealed a severer diabetic pattern and a lower response of C-peptide immunoreactivity. It is suggested therefore that the hypoglycemic effect of disopyramide may be due to increased insulin secretion of pancreatic beta cells.
