 Insulin resistance is defined as the decreased ability of insulin to perform its biological function in the muscle, liver and fat. Genetic and environmental factors are known to influence insulin sensitivity. It is not known how this is mediated. This study looks at the role of epigenetics modifications of proteins associated with DNA and methylation of DNA in alterations in insulin resistance. We will study lean healthy people, obese non-diabetic people and people with type 2 diabetes to characterize the DNA methylation patterns in muscle in each group. The second aim of the study is to see how a single bout of exercise affects the DNA methylation in the muscle. The third aim looks at the effect of 8 weeks of supervised exercise on the DNA methylation. 