ADIPOQ and obesity due to melanocortin 4 receptor deficiency: A tendency for a reduction in the circulating, saliva and gingival crevicular fluid levels of adiponectin in periodontitis in human studies, particularly those with co-existing obesity and type 2 diabetes mellitus, can be demonstrated but these finding are often disparate due to variable methods in case definitions, assay techniques, metabolic background of subjects and other confounders.