Reduction of blood pressure in obese hyperinsulinaemic hypertensive patients during somatostatin infusion

Hypertension in the obese may be related to hyperinsulinaemia. To investigate this relationship further, we infused somatostatin (250 μg/h in 100 ml saline) or saline, single-blind and in a random order, for 10 h in seven obese hyperinsulinaemic hypertensive patients and in seven normo-insulinaemic hypertensive controls. Every 2 h, blood pressure, plasma insulin, glucose, sodium, potassium, renin, cortisol and aldosterone concentrations and the urinary sodium: creatinine ratio were determinated. Two hours after the somatostatin infusion was started, mean arterial blood pressure was significantly reduced in the obese hyperinsulinaemic patients (from 128 ± 11 to 114 ± 11 mmHg, P<0.05) but not in the controls and this reduction persisted throughout the study. The somatostatin infusion reduced plasma insulin and increased plasma glucose similarly in both groups. Plasma sodium, potassium, renin, cortisol and aldosterone concentrations and the urinary sodium : creatinine ratio were unchanged after the somatostatin infusion. These results suggest that hyperinsulinaemia could help sustain the blood pressure rise in obesity.