Physical exercise is promoted as one of the primary therapeutic strategies available to increase insulin sensitivity in individuals deemed at risk from insulin resistance and its attendant hyperinsulinism. Subjects with non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) represent the major clinical population in which physical training is promoted as a treatment modality to improve insulin sensitivity. This manuscript reviews both the acute effects of muscular contractions and the effects of physical training on insulin sensitivity in NIDDM and insulin-dependent diabetic (IDDM) human subjects. Additionally, the effects of localized (regional) muscular contractions on insulin-mediated glucose disposal in previously exercised and nonexercised muscle groups will be discussed briefly.