A Review of Insulin Resistance in Type 1 Diabetes: Is There a Place for Adjunctive Metformin?

There is a rising trend of overweight and obesity among individuals with type 1 diabetes. This is often associated with insulin resistance, increased insulin dose requirements and poor glycemic control. Insulin resistance is also seen during puberty and is strongly related to increased risk of cardiovascular disease. The role of metformin as an adjunct to ongoing intensive insulin therapy in type 1 diabetics has been evaluated in several randomized trials, including the recently concluded T1D Exchange Network trial in adolescents and the REMOVAL trial in adults. Metformin reduces the insulin dose requirement, insulin-induced weight gain, and total and LDL cholesterol, but results in an increased risk of gastrointestinal adverse effects and a minor increase in the risk of hypoglycemia. In addition, metformin has been shown to reduce maximal carotid intima media thickness and therefore may extend cardioprotective benefits in type 1 diabetes. The role of metformin as adjunctive therapy in type 1 diabetes needs to be explored further in outcome trials.