Glucose intolerance and insulin resistance belong to the group of leading risk factors for breast (BC) and endometrial cancer (EC). Differences in the intensity of association of these endocrine disturbances with BC and EC may at least partly be explained by non-identity in polygenic nature of the mentioned hormone-metabolic shifts and oncological diseases themselves as well. In this study, which included 105 healthy postmenopausal women and 301 female cancer patients (110 BC and 191 EC) without overt diabetes mellitus, we compared the frequency of the following genetic polymorphisms: insulin receptor substrate-1, IRS Gly972Arg; leptin receptor, LEPR Lys109Arg and Gln223Arg; mitochondrial uncoupling protein-2, UCP2_866G/A; and gene ND3 of mitochondrial DNA, mtDNA 10398A/G. Genotyping was performed with allele-specific real-time PCR. According to data received, certain genetic markers associated with impaired glucose tolerance and/or insulin resistance (namely, leptin receptor genotypes 223 Gln/Arg and Gln/Gln) are revealed in oncological patients more often than in females without cancer. Other markers (like genotype UCP2 866AA and polymorphism mtDNA 10398A) appeared to be relatively more frequent in EC than in BC providing one of the interpretations for the lower insulin sensitivity and higher incidence of carbohydrate metabolism disturbances in the first of these two diseases.