Twenty patients were randomized to receive either 2.5 mg isradipine twice daily or 20 mg nifedipine retard once daily for 6 months. After 2 weeks of placebo wash-out, evaluations were carried out every 4 weeks. These evaluations included assessment of blood pressure, lipid profile, hemoglobin A1 sigma glucagon, C peptide, and insulin requirements. Both isradipine and nifedipine retard lowered systolic and diastolic blood pressures to normal values (P < .001). However, isradipine was accompanied by a decrease in heart rate (P < .005). Neither drug modified hemoglobin A1c or the glycemic profile. The endogenous insulin-secretion response decreased in both treatment groups (P < .05). In conclusion, isradipine and nifedipine retard are efficacious in the treatment of hypertension in patients with type II diabetes mellitus, and neither treatment produces modification of metabolic control.