Introduction: Metabolic syndrome (MS) is a composition of several cardiovascular risk factors with hyperinsulinemia being the main underling pathophysiological abnormality. Ankle-Brachial index (ABI) is a non invasive measure of peripheral artery disease and has been associated with cardiovascular risk. The purpose of this study was to evaluate the relationship between insulin levels and ABI in hypertensive patients with and without metabolic syndrome.

Methods: We studied 88 consecutive, non diabetic patients, mean aged 50 years, with newly diagnosed, uncomplicated essential hypertension. The patients were divided in two groups according to the presence of MS (38 patients with MS, 50 patients without MS), as defined by the criteria of the Adult Treatment Panel III. Fasting insulin levels and Hba₁cwere measured and HOMA index was calculated. ABI was assessed in all patients.

Results: The min ABI values were higher in hypertensives with MS (1.20 vs 1.15, p = 0.04) as were insulin (12.4 vs 9.1 μIU/ml, p = 0.02), HOMA index (57.5 vs 37.8, p = 0.007) and Hba₁c (5.80 vs 5.43%, p = 0.0003) values.In univariate analysis, insulin levels were associated with ABI in hypertensive patients with MS (r = 0.59, p < 0.001) but such an association was not found in hypertensives without MS (p = NS). After adjustment for several confounders, insulin remained significantly associated with ABI in patients with metabolic syndrome (r = 0.58, p = 0.001).

Conclusion: Fasting insulin independently predicts ABI in patients with hypertension and metabolic syndrome. This finding provides further information for the pathophysiology of the relationship between metabolic syndrome and the risk for peripheral artery disease.