No significant differences in IRS1 mRNA expression were detected in men vs women while T2D patients (N = 10) show lower IRS1 expression ( = mean −0.04 ± SD 0.14) than subjects without T2D (N = 31; = mean 0.08 ± SD 0.15) in SAT (P = 0.032). This evidence concerns the gene IRS1 and type 2 diabetes mellitus.