Clinical parameters (gingival bleeding index, periodontitis staging and grading), serum levels of TNF-α, HbA1c, leptin, adiponectin, resistin, free fatty acids (FFA), and levels of TNF-α, leptin, adiponectin, and resistin in gingival crevicular fluid (GCF) were assessed at baseline, 4 weeks, and 8 weeks post-treatment. This evidence concerns the gene RETN and periodontitis.