Objectives: Type 1 diabetes is a global health challenge, elucidating the underlying mechanisms of the disease might help identify novel early screening biomarkers and new therapeutic options for the disease. Recently, a growing body of research showed that immune checkpoint inhibitors such as Programmed death ligand 1 (PDL-1) are implicated in the development of the disease. Genomic alterations such as single nucleotide polymorphisms (SNPs) are tightly associated with susceptibility to various diseases. Methods: 50 patients with type 1 diabetes and 25 healthy volunteers were enrolled in this case-control study. Genomic DNA was extracted for sequencing the selected SNPs (rs822336 (-1813) GC, rs73641615 TC, rs73641616(-1491) GA, and rs822337(-1349) TA) SNPs in the promoter region of PD-L1 gene. Results: SNP analysis revealed the absence of any association between the SNPs investigated in the study and Type 1 diabetes, however, haplotype computational analysis using 1000 genome data suggested that (rs73641615) SNP might be a risk factor associated with the disease progression. On the contrary, our results suggested that A allele of SNP (rs73641616) might be not a risk factor in the disease, however, this result should be validated with further studies including a larger number of participants. Conclusions: Although several previous studies reported genomic alterations of Programmed death ligand one as a risk factor in the development of Type 1 diabetes, our study revealed that some alleles might be not associated with disease progression. However, further studies are highly recommended.