Using qRT-PCR, we examined the transcript levels of selected genes from the five respiratory complexes (I-V), TCA cycle, and fatty-acid oxidation, which were found to be downregulated in SAT of patients with T2D in the microarray analysis (p < 0.01) as well as the major transcriptional regulator of mitochondrial biogenesis, PPARGC1A. This evidence concerns the gene PPARGC1A and type 2 diabetes mellitus.