To the Editor.—
Antidysrhythmic calcium antagonists such as diltiazem hydrochloride are widely employed to treat vasospastic angina pectoris and arrhythmia. These drugs suppress the beta-cell secretory response via blockade of calcium channels1 and may be responsible for the reported variable effects on glucose metabolism in nondiabetics and patients with type II (non-insulin-dependent) diabetes.2 However, there are no reports of any diabetogenic effect in type I (insulin-dependent) diabetes mellitus.
Report of a Case.—
A 38-year-old woman with a 29-year history of insulin-dependent diabetes mellitus presented with shortness of breath, dyspnea on exertion, pretibial edema, cardiac arrhythmia, and severe angina pectoris. Kidney and liver functions were normal, with a creatinine level of 0.9 to 1.1 mg/dL (79 to 97 μmol/L) (normal range, 0.7 to 1.2 mg/dL [62 to 106 μmol/L]) over the period of observation. She was treated with quinidine (constant dose throughout observation), nitroglycerin as needed, and diltiazem (Figure).