Both type 1 diabetes and type 2 diabetes have a genetic component, with over 60 chromosomal regions related to type 1 diabetes and over 200 connected with type 2 diabetes at significant genome-wide levels. Numerous single nucleotide polymorphisms in the RETN gene and genetic variables can account for up to 70% of the variations in circulating resistin levels. The RETN polymorphism has been linked in numerous studies to obesity, insulin sensitivity, type 2 diabetes, and cerebrovascular illness. Our objective is to compare this RETN gene 3ʹ-untranslated region polymorphism in type 1 diabetes and type 2 diabetes Iraqi patients. We choose 51 type 1 diabetes and 52 type 2 diabetes patients against 50 healthy subjects (control group) to investigate the comparative RETN gene polymorphisms in patients with type 1 diabetes and type 2 diabetes, using conventional polymerase chain reaction. The present study revealed statistically there was no significant increase in CC, CG, and GG genotypes (with Odd Ratio 1.43, 0.82, and 0.62 respectively) in type 1 diabetes, and statistically there was no significant increase in CC, CG, and GG genotypes (with Odd Ratio 0.68, 1.02 and 1.97 respectively) in type 2 diabetes as compared to the control group. Also, we found statistically there was no significant increase in C and G alleles in type 1 diabetes and type 2 diabetes groups as compared to the control group. The findings suggest that the CC genotype and C allele in RETN gene 3ʹ-untranslated region polymorphism rs1862513 increase the risk of type 1 diabetes compared to CG and GG genotypes, and the G allele in this gene increases the risk of type 2 diabetes in Iraqi patients.