Our aim was to study how different BMI scores may influence in Portuguese patients previously diagnosed with T2DM the levels of inflammation, oxidative stress, adipogenesis, and glucose and lipid metabolism, by evaluating the circulating levels of oxLDL, CRP, and some adipokines—adiponectin, leptin, and chemerin—in lean, overweight, and obese Portuguese patients with type 2 diabetes. This evidence concerns the gene LEP and type 2 diabetes mellitus.