SUPPRESSION OF POST-GLUCOSE HYPERINSULINEMIA DOES NOT AFFECT BLOOD-PRESSURE IN EITHER NORMOTENSIVE OR HYPERTENSIVE SUBJECTS

1. Hyperinsulinaemia and insulin resistance are thought to be intimate ly involved in the development of hypertension, but controversy remain s as to whether hyperinsulinaemia is a consequence or a cause of hyper tension per se, and whether it plays a role in the short-term regulati on of blood pressure. 2. We studied six hypertensive patients [blood p ressure 161(9)/101(2) mmHg] and seven normotensive control subjects (b lood pressure 122(6)/76(4)mmHg], (P< 0.005) using two oral glucose tol erance tests of 3 h duration. In one of these tests the endogenous ins ulin response was inhibited with subcutaneous octreotide, 3.After plac ebo, hypertensive patients had slightly but significantly higher blood glucose levels than controls (P < 0.0001), but comparable insulin con centrations (P > 0.5), Plasma noradrenaline levels were consistently l ower in the hypertensive group (P < 0.001), Blood pressure did not cha nge in either group during the 3 h after glucose ingestion. 4.Octreoti de completely abolished the immediate insulin response to glucose in a ll subjects (both P< 0.0001) and caused a delayed and significantly in creased glycaemic response in both groups (P < 0.0001), There were no significant differences in plasma glucose responses between groups; ho wever, after octreotide, the hypertensive subjects had a greater insul in suppression than the controls (P < 0.02). Octreotide suppressed nor adrenaline levels in the normotensive group (P < 0.001); they were als o suppressed in the hypertensive group, but just failed to reach signi ficance (P = 0.056), Throughout the study the hypertensive groups nora drenaline levels remained generally lower than those in the control gr oup (P < 0.0001), 5.In this study there were no differences between hy pertensive and normotensive subjects in fasting or post-glucose insuli n levels, nor any significant change in blood pressure in either group when post-glucose hyperinsulinaemia was suppressed. This argues again st insulin playing a direct role in the short-term regulation of blood pressure.