Endothelial function is deteriorated in patients with type 2 diabetes and in patients with chronic heart failure. Treatment with carvedilol improves survival in patients with chronic heart failure compared to treatment with metoprolol. Carvedilol improves metabolic glucose control in patients with diabetes compared to metoprolol.Carvedilol compared to metoprolol also decreases the number of patients with new onset diabetes among patients with chronic heart failure. The mechanism behind these findings has not been fully understood.