Abstract
Insulin resistance is a risk factor for cardiovascular disease. Therapies to lower blood pressure should not decrease insulin sensitivity, especially among high-risk patients such as diabetics. This study examined the effect of the beta1-selective adrenergic receptor-blocking agent extended-release metoprolol succinate (ER metoprolol) on insulin sensitivity in type 2 diabetic patients with suboptimal blood pressure control. Diabetic patients with average blood pressure levels >130/85 mm Hg despite antihypertensive therapy had insulin sensitivity quantified by insulin clamp. ER metoprolol was then added to their ongoing therapy. Following 12 weeks of ER metoprolol plus other therapy, the insulin clamp study was repeated. There were no significant changes in measures of insulin sensitivity, plasma lipids, or hemoglobin A1c with use of ER metoprolol. When beta-blocker therapy is considered, it appears that this agent can be used to treat hypertension without adverse effects on insulin sensitivity in patients with type 2 diabetes, at least over the period of time treated.