Demographic analyses of the effects of carvedilol vs metoprolol on glycemic control and insulin sensitivity in patients with type 2 diabetes and hypertension in the Glycemic Effects in Diabetes Mellitus: Carvedilol-Metoprolol Comparison in Hypertensives (GEMINI) study.

In the Glycemic Effects in Diabetes Mellitus: Carvedilol-Metoprolol Comparison in Hypertensives (GEMINI) trial, carvedilol added to angiotensin-converting enzyme inhibitors and angiotensin receptor blockers had neutral or beneficial effects on glycemic measures compared with metoprolol tartrate. For the 1235 diabetic hypertensive GEMINI patients, the authors assessed treatment differences by race (white/black/other), age (continuous variable), and sex on hemoglobin A(1c), insulin resistance (homeostasis model assessment-insulin resistance [HOMA-IR]), and blood pressure. Both treatments significantly reduced blood pressure in all subgroups, but the metabolic effects of carvedilol were more beneficial in subgroups of race and sex. Carvedilol did not affect hemoglobin A(1c) but improved HOMA-IR results in all subgroups, significantly in males and "other race" subgroups. Metoprolol significantly increased hemoglobin A(1c) in all subgroups except "other race," with no effect on HOMA-IR findings. Differences vs metoprolol significantly favored carvedilol for hemoglobin A(1c) in white and female subgroups and favored carvedilol for HOMA-IR in black, "other race," and male subgroups. Carvedilol effects were favorable to adjustment of age as a covariate. In hypertensive patients with diabetes, carvedilol may be a more appropriate choice when beta-blockade is indicated.