In summary and despite the limitations, our study is the first to report serum concentrations of adiponectin, resistin, and leptin and show a beneficial effect of n-3 PUFA supplementation on waist circumference, glucose, glycosylated hemoglobin, leptin, and leptin/adiponectin ratio and lipid profile in a group of Mexican individuals with T2DM. The gene discussed is LEP; the disease is type 2 diabetes mellitus.