Background: Some patients with essential hypertension display hyperinsulinemia and/or insulin resistance. A relationship between hyperinsulinemia and blood pressure has not been conclusively established. Some evidence points to a relationship between hyperinsulinemia and evidence of cardiovascular damage.
Objectives: In this study, we examined the relationship between insulin secretion in response to an oral glucose load, circadian variation of blood pressure, and evidence of vascular damage, measured by the thickness of the carotid artery and urinary albumin excretion.
Design: Seventy patients with essential hypertension and 35 healthy volunteers were included in the study.
Results: Twenty patients were hyperinsulinemic. Office blood pressure was not different between hypertensive patients with high and those with normal insulin AUC. However, night-time diastolic blood pressure was greater in hypertensive patients with high insulin AUC (93 +/- 2.9 mm Hg) than in those with normal insulin AUC (83.5 +/- 1.7 mm Hg, P < 0.005). The thickness of the carotid artery and urinary albumin excretion were greater (P < 0.05) in patients with high insulin AUC than in patients with normal insulin AUC and normotensive subjects. Insulin AUC was significantly correlated with ambulatory blood pressure, carotid artery thickness, and urine albumin excretion. Multiple regression analysis using insulin AUC as the dependent variable and UAE, triglycerides, body-mass index and office or ambulatory blood pressure as independent variables showed the strongest correlation with urine albumin excretion (P < 0.0001), triglycerides (P < 0.02) and body-mass index (P < 0.07).
Conclusions: These data suggest that in patients with essential hypertension hyperinsulinemia is associated with higher levels of nocturnal blood pressure, and greater evidence of vascular damage.