Genetic and environmental contributions

There is a remarkable variability in insulin action in humans. Depending upon the definition of the insulin resistance syndrome, different inheritability/environmental influences on insulin action are reported. The environmental contributions to insulin resistance appear to account for ~50% of this syndrome. Obese and sedentary insulin-resistant individuals can see dramatic improvement in insulin sensitivity with weight reduction and fitness training. The degree to which obesity is determined by genetic influences will have a substantial impact on insulin resistance in the Western populations. Familial components also appear to account for ~50% of the variation and insulin action (as commonly defined by glucose metabolic effects).