Over the past several years, Beth Israel Deaconess Medical Center (BIDMC) endocrinologist Barbara Kahn, MD, has developed a large body of research suggesting that a molecule called retinol binding protein 4 (RBP4) plays a key role in the process. Kahn's lab was the first to show that elevated levels of RBP4 -- previously known only for its role as a transport protein for Vitamin A -- led to the development of insulin resistance in animal models.

Additional work revealed parallel results in human blood samples: obese, insulin-resistant individuals had high RBP4 levels and lean, insulin-sensitive people had low RBP4 levels. Furthermore, people with genetic changes in RBP4 that resulted in high blood levels of the protein had an elevated risk of developing diabetes.