OBJECTIVETo assess the association between leptin gene promoter methylation and serum leptin concentrations in patients with impaired glucose regulation (IGR) and type 2 diabetes mellitus (T2DM).

METHODSMethylation status of leptin gene promoter was determined with methylation-specific polymerase chain reaction. Serum leptin concentrations were determined using enzyme-linked immunosorbent assay.

RESULTSAmong three groups of individuals with different levels of glucose, the methylation rates of leptin gene in IGR and T2DM groups were 43.6 % and 31.5 %, respectively, which were significantly lower than that of healthy subjects (59.2%; Chi-square=22.499 and 5.109, respectively, P<0.05). A lower methylation rate was also observed in T2DM group compared with IGR group (Chi-square=3.962, P<0.05). Leptin levels in both T2DM and IGR groups were elevated compared with normoglycemic subjects, but only T2DM group was significantly higher (q=6.81, P<0.01). Linear regression analysis indicated that serum leptin concentrations has increased along with declining of DNA methylation rate (r=-0.95, P<0.01).

CONCLUSIONLower levels of leptin gene promoter DNA methylation and serum leptin concentrations are associated with the development of diabetes. Measurement of the methylation status of leptin gene promoter and expression can facilitate early intervention of the disease.