Are insulin and hypertension independently related?

Hyperinsulinemia has been proposed as the common pathogenetic mechanism of obesity, non-insulin-dependent diabetes mellitus, and hypertension. We examined the cross-sectional relationship between fasting and postchallenge insulin levels and hypertensive status in a population-based study of 653 men and 784 women, aged 50 to 93 years, in Rancho Bernardo, California. Hypertensive subjects had slightly but not significantly higher fasting plasma insulin levels than did normotensive subjects, but significantly higher postchallenge insulin levels. After stratification for obesity and glucose intolerance, there was no significant difference between the mean age-adjusted fasting or postchallenge insulin levels of those with and those without hypertension in 12 possible subgroups. Analysis of variance of both fasting and postchallenge insulin levels also failed to reveal a significant relationship between insulin and hypertensive status after adjusting for age, sex, body mass index, and diabetes. The current study does not support the hypothesis that insulin is independently associated with hypertension.