In eight hypertensive diabetic subjects receiving hydrochlorothiazide, glucose homeostasis as measured by the changes in plasma glucose, insulin and glucagon after an oral glucose load was not significantly affected by 8 weeks of therapy with metoprolol. 2. The combination of metoprolol plus hydrochlorothiazide significantly lowered blood pressure in all subjects. 3. Plasma renin activity was suppressed by therapy with metoprolol.