Metabolic syndrome and insulin resistance in the TROPHY sub-study: Contrasting views in patients with high-normal blood pressure

Background Although insulin resistance and metabolic syndrome are often used synonymously, concordance is not established. Methods Metabolic, hemodynamic, and hormonal data were analyzed on 141 patients in the Trial of Preventing Hypertension (TROPHY) Sub-Study with high-normal blood pressure (BP) (130 to 139/85 to 89 mm Hg [mean ± SD, 133 ± 8/85 ± 6 mm Hg]; age, 48 ± 9 years; body mass index 30 ± 5 kg/m2). Results Fifty-three of 141 subjects (37.6%; 3/8) had the metabolic syndrome based on three or more of the five risk factors (BP, waist circumference, fasting triglycerides, HDL-cholesterol, glucose). To maintain consistency in proportions, insulin resistance was defined as the upper 3/8 of the distribution on the homeostatic model assessment (HOMA), which uses fasting glucose and insulin and a modified Matsuda-DeFronzo index, based on fasting, 1- and 2-h glucose and insulin values. Among metabolic syndrome patients, 57% and 55% were in the upper 3/8 of the distribution for insulin resistance by HOMA and Matsuda-DeFronzo, respectively. Among subjects without the metabolic syndrome, 26% and 27% were insulin resistant by HOMA and Matsuda-DeFronzo criteria. The proportion of patients with metabolic syndrome and insulin resistance increased strongly and similarly with increasing body mass index. However, metabolic syndrome and insulin resistance were different compared with their respective controls in the lower 5/8 of the distribution, in waist/hip ratios, fasting and 1-h insulin, HDL-cholesterol, heart rate, and systolic BP responses to exercise and plasma renin, angiotensin, and aldosterone. Conclusions The findings suggest that metabolic syndrome and insulin resistance are not synonymous anthropometrically, metabolically, hemodynamically, or hormonally in patients with high-normal BP.