Effects of chronic hyperinsulinemia in insulin-resistant patients.

Selective insulin resistance influences pathogenesis and treatment of type 2 diabetes and metabolic syndrome. Downregulation of the antiatherogenic pathway and maintained activity of the proatherogenic and cancerogenic pathways lead to atherosclerosis and cancer. Exogenous insulin added to "compensatory" hyperinsulinemia might worsen the primary end points, resulting in potential increase in cardiovascular and cancer events in spite of improvement of surrogate metabolic end points. Conversely, metformin can improve primary and surrogate end points.