Objective: Improvement in endothelial function is predicted to improve insulin sensitivity, and this may be one mechanism by which fenofibrate decreases the incidence of coronary heart disease. We hypothesize fenofibrate improves endothelial function by enhancing insulin sensitivity.
Research design and methods: We administered placebo or fenofibrate 200 mg daily for 8 weeks to 46 patients with primary hypertriglyceridemia (24 had metabolic syndrome). This study was randomized, double blind, placebo controlled, and crossover in design.
Results: Compared with placebo, fenofibrate decreased total cholesterol, non-HDL cholesterol, apolipoprotein B, and triglycerides and increased HDL cholesterol and apolipoprotein A-I (all P < 0.001) while tending to decrease LDL cholesterol (P = 0.069). Fenofibrate significantly improved percent flow-mediated dilator response to hyperemia by 48 +/- 5% (P < 0.001) and lowered plasma levels of high-sensitivity C-reactive protein (hsCRP) relative to baseline measurements from 0.80 to 0.70 mg/l (P = 0.001) and fibrinogen levels by 16 +/- 3% (P < 0.001). Compared with placebo, fenofibrate therapy significantly increased plasma levels of adiponectin by 14 +/- 5% (P = 0.008) and increased insulin sensitivity (assessed by quantitative insulin sensitivity check index [QUICKI]) by 6 +/- 2% (P = 0.048). There were significant correlations between percent changes in adiponectin levels and percent changes in flow-mediated dilation (r = 0.401, P = 0.006), hsCRP (r = -0.443, P = 0.002), or QUICKI (r = 0.292, P = 0.049). Multivariate regression analysis showed that only changes in adiponectin levels persisted as an independent predictor of changes in flow-mediated dilation (r = 0.504, P = 0.013). Overall, we observed similar results in 24 patients with metabolic syndrome.
Conclusions: Fenofibrate therapy significantly improved percent flow-mediated dilator response to hyperemia, reduced inflammation marker levels, increased adiponectin levels, and improved insulin sensitivity in hypertriglyceridemic or metabolic syndrome patients.