Background/aim: We proposed to investigate the role of calpain-10 (CAPN10) gene single nucleotide polymorphism (SNP)-19 and SNP-44 and glucocorticoid receptor (NR3C1) gene N363S polymorphisms in Turkish patients with type 2 diabetes mellitus (T2DM).Materials and methods: Peripheral blood samples were obtained from 125 patients with T2DM and 112 healthy volunteers. Genotyping was carried out by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results: There were no statistically significant differences found between the allele and genotype frequencies of CAPN10 SNP-19, CAPN10 SNP-44, and NR3C1 N363S polymorphisms and T2DM development (P > 0.05). The CAPN10 SNP-19 del-allele, CAPN10 SNP-44 C-allele, and NR3C1 N363S G-allele were determined to be risk factors for T2DM development. In T2DM patients an association was identified between the CAPN10 SNP-19 del-allele, homozygous del/del genotype, SNP-44 C-allele, heterozygous TC genotype, NR3C1 N363S G-allele, heterozygous AG genotype, and increased BMI. Conclusion: The present study demonstrates that the SNP-44 polymorphism is associated with T2DM susceptibility and contributes to the risk of T2DM.