1 Twelve non-diabetic hypertensive male patients insufficiently controlled by a diuretic were included in a double-blind, randomised study. In addition placebo or felodipine was given for 4 weeks followed by a 2 week wash-out period, after which the alternative treatment was given for another 4 weeks. At the end of each treatment period an oral glucose tolerance test (OGTT) was performed and blood pressure, plasma noradrenaline and felodipine levels were measured. 2 There was no change in either glucose, insulin or glucagon levels during the OGTT after felodipine compared with placebo. Blood pressure was significantly reduced during the dosage interval of felodipine (12 h). Plasma noradrenaline increased significantly after felodipine. Side effects were few. 3 In a separate open study 58 hypertensive patients were treated with felodipine in addition to a diuretic and a beta-adrenoceptor blocker for up to 1 year. There were no significant changes in fasting blood glucose levels during the study.