Although both metformin and thiazolidinediones (TZDs) have been shown to decrease insulin resistance, metformin demonstrates a slightly positive osteogenic effect by stimulating proliferation and differentiation in osteoblastic cell lines [28]; however, TZDs, such as rosiglitazone, may increase bone loss and fracture risk via peroxisome proliferator-activated receptor gamma (PPARγ) agonist activity negatively affecting bone formation [29,30,31]. The gene discussed is PPARG; the disease is Insulin resistance.