In T2D patients, basal PAI-1 activity levels significantly correlated with HOMA-IR (r = 0.226; P < 0.05), basal plasma insulin levels (r = 0.225; P < 0.05), and HDL-chol levels (r = −0.384; P < 0.001), while percentage of PAI-1 decrease during the day significantly correlated only with AUC of insulin levels (r = −0.483; P < 0.05). This evidence concerns the gene SERPINE1 and type 2 diabetes mellitus.