Diabetes in Mice With Selective Impairment of Insulin Action in Glut4-Expressing Tissues

OBJECTIVE-Impaired insulin-dependent glucose disposal in muscle and fat is a harbinger of type 2 diabetes, but murine models of selective insulin resistance at these two sites are conspicuous by their failure to cause hyperglycemia. A defining feature of muscle and fat vis-a-vis insulin signaling is that they both express the insulin-sensitive glucose transporter Glut4. We hypothesized that diabetes is the result of impaired insulin signaling in all Glut4-expressing tissues. RESEARCH DESIGN AND METHODS-To test the hypothesis, we generated mice lacking insulin receptors at these sites (GIRKO mice), including muscle, fat, and a subset of Glut4-positive neurons scattered throughout the central nervous system. RESULTS-GIRKO mice develop diabetes with high frequency because of reduced glucose uptake in peripheral organs, excessive hepatic glucose production, and beta-cell failure. CONCLUSIONS-The conceptual advance of the present findings lies in the identification of a tissue constellation that melds cell-autonomous mechanisms of insulin resistance (in muscle/fat) with cell-nonautonomous mechanisms (in liver and beta-cell) to cause overt diabetes. The data are consistent with the identification of Glut4 neurons as a distinct neuroanatomic entity with a likely metabolic role. Diabetes 60:700-709, 2011