It has recently been reported that blood pressure elevation precedes the development of type 2 diabetes in the metabolic syndrome by 20 or more years, implying that vascular dysfunction may lead to insulin resistance. We hypothesized that the two processes occur in parallel, rather than sequentially.

Twenty-six individuals selected to represent a spectrum of insulin sensitivities underwent the hyperinsulinemic, euglycemic clamp. Blood pressure was measured by trained personnel at an initial screening visit and during the insulin clamp. Other typical measures of insulin sensitivity such as HOMA, QUICKI and the ¹³C-glucose breath test were also performed. Association of blood pressure with indices of insulin sensitivity was assessed by determination of correlation coefficients and by regression analysis.

There were strong, statistically significant inverse correlations between baseline blood pressures (systolic, diastolic and mean) and glucose disposal rate and insulin sensitivity index as measured by the hyperinsulinemic clamp. Neither the commonly used HOMA index or the slightly more complex QUICKI index correlated with blood pressures. The ¹³C-glucose breath test results did correlate with blood pressures, but not as strongly as the variables from the insulin clamp. Correlations between insulin resistance and blood pressure were independent of body weight, age and other variables.

We conclude that changes in blood pressure and changes in insulin sensitivity are closely linked and that previous studies may not have used sufficiently sensitive indicators of insulin resistance. Thus, results from this study tend to support the hypothesis that insulin resistance and vascular dysfunction occur as a result of a common, underlying mechanism rather than one being the cause of the other.

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