Introduction: Type II diabetes is the most common form of diabetes and accounts for 90 percent of disease cases. CTLA4 represents a key regulatory element in the T cell/antigen-presenting cell interaction. Because CTLA4 involves in antigen-specific apoptosis and progressive failure of B-cell, a typical feature of type 2 diabetes, CTLA4 may be a candidate gene to indicate type  2 diabetes susceptibility. The aim of this study was to investigate the role of polymorphisms of CTLA-4 gene in type II diabetic patients compared with healthy subjects.

Materials & methods: In this case-control study, the blood samples were collected from 100 patients and 111 controls from Sanandaj, Hamedan and Kermanshah cities. After DNA extraction, the polymorphisms of CTLA-4   was investigated by ARMS-PCR method. Then, statistical analysis of results was performed using chi-square test.

Findings: The results show that the GG genotype at position +49 [OR (95% CI) = 1.92 P = 0.02] and in position - 318 TT and CT [OR (95% CI) = 9.80 P = 0.02] are a risk factor for Type II diabetes, while on position -1722 T/C [OR (95% CI) = 1.85 P =0.50] doesn’t have significant relationship.

Discussion & conclusions: These results suggest that the polymorphisms +49 A/G and -318 C/T of CTLA-4 gene have significant relationship with  type II diabetes, without any significant relationship with the  position of -1722 T/C.