Expression of genes involved in lipid metabolism in men with impaired glucose tolerance: impact of insulin stimulation and weight loss

Background: The impaired glucose tolerance (IGT) state is characterized by insulin resistance. Disturbances in fatty acid (FA) metabolism may underlie this reduced insulin sensitivity. The aim of this study was to investigate whether the prediabetic state is accompanied by changes in the expression of genes involved in FA handling during fasting and in insulin-mediated conditions and to study the impact of weight loss. Methods: Seven IGT men and 5 men with normal glucose tolerance (NGT), comparable in terms of age and BMI, participated in the study. The 5 IGT men followed a 12-week weight loss program. Muscle biopsies were taken and the expression of 6 genes was investigated. Results: Subjects had a reduction of 15.5 +/- 4.3 kg in body weight. Baseline gene expression was not different between NGT and IGT men. After a hyperinsulinemic clamp, there was an overall upregulation of PGC1 alpha, SREBP-1c, SREBP-2, and ACC-2. The upregulation of SREBP-2 was more pronounced in IGT men (p = 0.049). Weight loss significantly increased insulin sensitivity by 71%, which was not reflected in altered gene expression profiles. Conclusions: SREBP-2 shows altered insulin responsiveness in IGT men compared with NGT men, while there were no differences in basal gene expression. Copyright (C) 2010 S. Karger AG, Basel