The insulin sensitivity response is determined by the interaction between the G972R polymorphism of the insulin receptor substrate 1 gene and dietary fat

Scope: Insulin resistance, a condition associated with type 2 diabetes mellitus, results from the interaction of environmental and genetic factors. The aim of this study was to explore the influence of the G972R polymorphism at the insulin receptor substrate 1 gene on insulin sensitivity in a healthy young population. Furthermore, we examined whether the presence of this single nucleotide polymorphism (SNP; GR or GG) interacts with dietary fat tomodulate insulin sensitivity. Methods and results: Fifty-nine healthy volunteers consumed three diets during 4wk each following a randomized crossover design: a saturated fatty acid diet, a low-fat and high carbohydrate (CHO) diet or a MUFA diet. For each diet, we investigated peripheral insulin sensitivity with the insulin suppression test. Steady-state plasma glucose and plasma-free fatty acids concentrations were significantly lower in GR subjects after the intake of a CHO diet, than did homozygous GG subjects (p<0.05). However, no differences were observed after consuming the two other diets. Conclusions: Insulin sensitivity increased in GR subjects for the G972R polymorphism at the insulin receptor substrate 1 gene locus, after intake of a CHO diet. Increased knowledge of how these and other genes influence insulin sensitivity should increase the understanding of personalized nutrition.