PPARGC1A and type 2 diabetes mellitus: Furthermore, HIIT-induced changes in protein expression of PGC1α (Peroxisome Proliferator-activated Receptor gamma Coactivator 1 α), a key regulator of mitochondrial biogenesis,4 returned to baseline levels in T2D and IR-NDM after detraining (Fig. 2f), in accordance with a previous study.19