Cardiovascular risk factors associated with insulin resistance: effects of oral antidiabetic agents

Patients with type 2 diabetes mellitus have a greater risk of cardiovascular disease than nondiabetic individuals. These patients are often insulin resistant and have an associated clustering of risk factors that contribute to cardiovascular disease. The risk factors include dyslipidemia, hypertension, altered hemostasis, and chronic inflammation. A primary objective in the management of type 2 diabetes mellitus is normalization of blood glucose levels; however, some of the oral drugs used to control blood glucose levels have significant effects on these risk factors. In this article, we review the current data involving the modification of these cardiovascular risk factors by the biguanide (metformin), the thiazolidinediones (troglitazone, rosiglitazone, and pioglitazone), the alpha-glucosidase inhibitors (miglitol, acarbose), and the insulin secretagogs (glyburide [glibenclamide], glipizide, chlorpropamide, tolbutamide, tolazamide, glimepiride, repaglinide, and nateglinide). Generally, the thiazolidinediones improve hemostasis and endothelial function and reduce blood pressure, while having variable effects on dyslipidemia. Metformin improves dyslipidemia and altered hemostasis and decreases plasma C-reactive protein levels with little or no effect on blood pressure. Data on the effects of the alpha-glucosidase inhibitors and insulin secretagogs are sparse; however, these drugs appear to have little or no effect on cardiovascular risk factors.