Type II diabetes mellitus (T2DM) of the second type is a chronic multifactorial disease that develops due to insulin resistance. Currently, more than 100 genes have been described that are associated with the risk of developing T2DM.Taking into account, that obesity is one of the factors predisposing to the development of type 2 diabetes, it seems appropriate to study the genes responsible for the formation of addictive behavior, in this case, eating behavior. The aim of the study was to analyze the association of polymorphic locus rs6313 of the HTR2A gene with T2DM and its complications in Tatars from Republic of Bashkortostan. The duration of T2DM was associated with the rs6313 locus of HTR2A gene; thus, among carriers of the AC and CC genotypes, the duration was 6.87 (0.53) years, while for carriers of the AA genotype only 4.79 (0.54) (P=0.018). There was an association with the risk of developing diabetic cataracts for carriers of the CC genotypers6313 locus of HTR2A gene, which accounted for 40%, while among patients without cataracts, the number of CC carriers was only 16.6% (OR = 3.36 95% CI 1.25-9.00, P = 0.02). The number of carriers of the AC and CC genotypes rs6313 locus of HTR2A gene among patients with polyneuropathies reached to 80.8% versus 61.8% among patients without this complication (OR = 2.60 95%CI 1.29-5.23, P = 0.005).