To further elucidate the anti-inflammatory activity of melatonin, we conducted clinical trials, aimed at determining the effect of topical application of melatonin on gingival crevicular fluid levels of IL-6, IL-1β and PGE2 in patients with diabetes and perio-dontal disease and evaluating the changes in two clinical parameters, gingival index and pocket depth, and the interrelation bet-ween them. This evidence concerns the gene IL1B and diabetes mellitus.