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).
Pershadsingh HA, Grant N, McDonald JM. Association of Diltiazem Therapy With Increased Insulin Resistance in a Patient With Type I Diabetes Mellitus. JAMA. 1987;257(7):930-931. doi:10.1001/jama.1987.03390070050021