Insulin resistance and the effect of insulin on blood pressure in essential hypertension.
The aim of this study was to investigate the effect of 2 weeks of insulin administration on blood pressure and to simultaneously measure insulin sensitivity and insulin-induced vasodilatation in obese hypertensive patients. In a prospective, randomized, double-blind, crossover study (study 1), 23 obese, untreated, nondiabetic, hypertensive patients received either neutral protamine Hagedorn (NPH) insulin (0.3 U/kg body wt per day) or placebo subcutaneously for 2 weeks (washout period, 2 weeks). Office and 24-hour blood pressure values were measured at the beginning and end of each treatment period. In an open-label study (study 2), 8 obese hypertensive patients and 10 healthy control subjects underwent a 3-step hyperinsulinemic, euglycemic glucose clamp (step 1, 0.5; step 2, 2.5; step 3, 5.0 mU x kg(-1) x min(-1) [120 minutes each]). Leg blood flow (LBF) was measured by venous occlusion plethysmography. Insulin administration decreased mean+/-SD office blood pressure from 131+/-13 to 128+/-12 mm Hg (placebo, 132+/-13 and 132+/-13 mm Hg; P<0.05 between final examinations) and mean+/-SD 24-hour blood pressure by -3.3+/-6.9 mm Hg (placebo, +0.7+/-4.6 mm Hg; P<0.05). Insulin infusion increased LBF significantly in the healthy controls but not in obese insulin-resistant hypertensive subjects. Obese hypertensive patients are resistant to the effects of insulin with regard to both glucose uptake and vasodilatation. Administration of insulin exerts a small blood pressure-lowering effect in these patients. These data strongly argue against the postulated pressor action of insulin in essential hypertension.
Department of Metabolic Diseases and Nutrition, Heinrich-Heine University, Düsseldorf, Germany. tim.heise@uni-duesseldorf.de
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Heise
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Magnusson
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Heinemann
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Sawicki
D000279:Administration, Cutaneous; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology*; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D014664:Vasodilation / Q000187:drug effects
D007004:Hypoglycemic Agents; D007328:Insulin