Cyclin D2, a driver of postnatal β cell expansion and β cell compensation for insulin resistance (1, 16–20), binds to and activates cyclin-dependent kinase (CDK) family members CDK4 and 6 to hyperphosphorylate the retinoblastoma (Rb) protein and derepress E2F transcription factors. This evidence concerns the gene CCND2 and Insulin resistance.