PPARGC1A and type 2 diabetes mellitus: The major genetic variants for the T2DM risk in Asians and Europeans are related to the β-function, even though some peroxisome proliferator-activated receptor-gamma (PPARγ), PPARγ coactivator 1-alpha (PGC−1a), and insulin receptor substrate−1 (IRS1) genetic variants are associated with the insulin sensitivity [9,10,11].