Use of antihypertensive agents in patients with glucose intolerance.

The selection, use, and potential adverse effects of antihypertensive agents in patients with glucose intolerance are reviewed. Thiazide diuretics frequently impair glucose tolerance, but this deterioration is usually modest and should not preclude use of these agents in most patients with glucose intolerance. The loop diuretics furosemide and ethacrynic acid have also been associated with decreased glucose tolerance. The beta-adrenergic blocking agents may inhibit insulin secretion, but few patients will experience clinically important elevations in blood glucose. Rather than producing glucose intolerance, these agents may delay recovery from hypoglycemic episodes and may mask catecholamine-induced symptoms of hypoglycemia. In certain cases, use of cardioselective beta blockers or avoidance of beta-blocker therapy may be indicated, especially in insulin-dependent diabetics. The calcium-channel blocking agents nifedipine and verapamil have been reported to produce diabetogenic effects in a few studies, but further investigations are needed to define the extent of these effects. Available evidence indicates that sympatholytic agents such as guanethidine and reserpine, alpha 2-adrenergic agonists such as methyldopa and clonidine, the alpha 1-blocking agent prazosin, and the vasodilators captopril and hydralazine produce few, if any, clinically important changes in glucose tolerance. While no antihypertensive agents are absolutely contraindicated in patients with glucose intolerance, patients with glucose intolerance who are receiving thiazide diuretics, beta blockers, and calcium-channel blocking agents should be monitored with extra care for hyperglycemia or deterioration in glucose tolerance.