Insulin resistance, insulin, proinsulin, and ambulatory blood pressure in type II diabetes.

Both insulin resistance and insulin concentrations correlate with blood pressure in nondiabetic subjects, but there is no consensus on these relations in subjects with non-insulin-dependent diabetes, perhaps because of the use of nonspecific insulin assays and clinic blood pressure measurement. Therefore, we have investigated the relation between ambulatory blood pressure, insulin sensitivity (measured by an insulin sensitivity test), and levels of insulin and its principal precursors, measured by specific assays, in 24 subjects with non-insulin-dependent diabetes. Insulin sensitivity (glucose metabolic clearance rate) correlated strongly with mean 24-hour ambulatory systolic blood pressure (r = -.650, P < .001). In contrast, there was no relation between this blood pressure index and fasting levels of insulin (r = .096, P = NS) or all insulin-like molecules (r = .077, P = NS). Dichotomized on 24-hour ambulatory systolic blood pressure levels, the hypertensive group was more insulin resistant than the normotensive group (metabolic clearance rate, 3.6 [0.7] versus 6.5 [3.0] mL.kg-1.min-1, P = .006), whereas there was no difference in insulin or proinsulin concentrations among the groups. In multiple regression analysis, insulin sensitivity was the major determinant of blood pressure. We conclude that in subjects with non-insulin-dependent diabetes mellitus, blood pressure is related to insulin sensitivity but not to fasting levels of insulin, suggesting that hyperinsulinemia is probably not the mediator of this relation.