Efficacy of controlled-release niacin in treatment of metabolic syndrome: Correlation to surrogate markers of atherosclerosis, vascular reactivity, and inflammation

BackgroundThe mechanisms that link metabolic syndrome to development of atherosclerosis are largely unknown. There is increasing evidence for the role of adipokines in this process. Niacin would appear to be a logical choice in combating the atherogenic dyslipidemia seen in metabolic syndrome, as it remains the most effective agent in raising high-density lipoprotein cholesterol, and also reduces triglycerides. We hypothesized that statin-intolerant patients with insulin resistance would respond to controlled-release niacin with a rise in plasma adiponectin levels.MethodsFifty patients with the metabolic syndrome (National Cholesterol Education Program/Adult Treatment Panel III criteria) were randomized to either once-daily controlled-release niacin (1000 mg/day) or placebo. Measurements at baseline and after 52 weeks of treatment were made of the carotid intimal media thickness, flow-mediated dilation of the brachial artery, and blood plasma adiponectin levels. These measures were compared to changes in lipoprotein concentrations in plasma.ResultsChanges in high-density lipoprotein cholesterol correlated significantly to changes in flow-mediated vasodilation and carotid artery intima-media thickness, and there was a trend toward correlation with plasma adiponectin levels. There was a significant difference in mean serum levels of adiponectin after the treatment period between placebo and niacin groups (16.3 ± 1.7 and 17.7 ± 1.9 mg/dL, respectively) (P = 0.022).ConclusionsTreatment with controlled-release niacin for 52 weeks results in sustained improvements in adiponectin levels compared to placebo in patients with metabolic syndrome. No adverse effects of niacin on glycemic control were found.