Diabetes mellitus is often associated with hypertension and is an additional cardiovascular risk factor. It is therefore important that antihypertensive drugs should have no negative metabolic effects. We present here the results of two distinct studies investigating the clinical efficacy and the metabolic effects of lacidipine in hypertensive patients without concomitant diabetes. Patients in the first study (group A) were hypertensive with non-insulin-dependent diabetes mellitus (NIDDM) and stable blood glucose levels in the 3 months before entering the study. Patients in the second study (group B) were hypertensive without diabetes mellitus. Before the commencement of the study, antihypertensive treatment was discontinued in all patients for a 4-week washout period, followed by 4 weeks of run-in with placebo. Patients were then treated with lacidipine (4 mg o.d.) for 6 months. After 1-2 months, the dose was doubled in patients with uncontrolled blood pressure. Every 2 months, lipid and carbohydrate metabolism were investigated by blood chemistry analyses. The results demonstrate that lacidipine 4-8 mg o.d. is efficacious and well tolerated in hypertensive patients, even in the presence of diabetes mellitus.