Ciprofibrate and Pre-diabetes

Overview

Free fatty acids (FFA) are the main fuel source in a healthy adult heart, since they are responsible for 70-80% of the myocardial ATP production. Plasma FFA and triglycerides (TG) levels are elevated in obesity and diabetes, evoking substrate competition in the heart: the increased availability of lipids will lead to fat accumulation in the heart, which is associated with cardiac insulin resistance and will therefore restrain insulin-stimulated cardiac glucose oxidation. It is shown that a lower myocardial glucose uptake correlates with decreased diastolic function. The benefits of counterbalancing this lipid overload is proven by previous research in pre-diabetes, which showed the reversibility of impaired myocardial substrate metabolism and improvement of function and structure after modest weight loss induced by lifestyle changes. Ciprofibrates are a ligand of the peroxisome proliferator-activated receptor (PPAR) α and are considered to be a major regulator of the lipid metabolism and promote fat oxidative capacity. They are not only effective in normalizing lipid-lipoprotein levels in patients with the metabolic syndrome, but improve also their insulin sensitivity. We therefore hypothesize that ciprofibrate administration in subjects with impaired glucose metabolism (IGM) influence the myocardial substrate metabolism (via the PPARα pathway) and thereby improve myocardial insulin sensivity.

Objectives: The main objective of the study is to investigate whether ciprofibrate treatment can improve myocardial insulin sensitivity in subjects with IGM. As secondary objectives we want to investigate whether ciprofibrate treatment also improves diastolic and myocardial mitochondrial function and decreases intracardiomyocellular lipid content. Futhermore, since ciprofibrate could also affect cardiac metabolism indirectly, we want to investigate the effect of ciprofibrate on skeletal and hepatic glucose uptake, hepatic lipid storage and composition. Study design: In a randomized, double-blind, cross-over design, the effects of ciprofibrate supplementation on myocardial insulin sensitivity will be compared to placebo in humans with IGM. Study population: Twelve male, overweight (BMI \> 27 kg/m2), insulin-resistant subjects, aged between 40 and 70 years, without cardiac disease, will participate in this study. Intervention: Subjects will be asked to take one pill of ciprofibrate 100mg, or placebo, once daily (at dinner), for 35 days. Main study parameters/endpoints: The main study endpoint is the difference in myocardial insulin sensitivity (measurement of glucose uptake using radio-active labeled 18F-FDG tracer in PET-MRI) after ciprofibrate administration compared to the placebo trial.