LEP and diabetes mellitus: Adiponectin and leptin are the most abundant adipocytokines produced by adipocytes and have anti- and pro-inflammatory properties, respectively.4,5 Smoking may cause a decrease in adiponectin levels,6–10 and decreased adiponectin levels have been consistently associated with DM incidence.11–14 With regard to leptin, previous studies on its association with smoking have often yielded conflicting results: reports of decrease,15–18 no effect,19 or increase20,21 in the leptin levels of smokers are all available.