Background and purpose: Diabetes is a multifactorial disease in which genetic factors, environmental and immunological factors are involved in its pathogenesis. Due to the immunological role of blood groups, this study aimed to evaluate the distribution of ABO blood groups and Rh types in patients with type 2 diabetes in north of Iran.

Materials and methods: This cross-sectional study was performed in type 2 diabetic patients referring to academic endocrine clinics in Sari, Iran, 2015. Relevant information including age, sex, history of hypertension, dyslipidemia and diabetes chronic complications were extracted from patients’ files. The red blood cell surface antigens were detected by direct standard slide agglutination technique.

Results: We studied 1500 diabetic patients of whom 590 (39.3%) had O blood type. The distribution of other blood groups were as follows: A: 26.2%, B: 26.7%, and AB: 7.8%. Compared with the society, in patients with type 2 diabetes, the distribution of A blood group was found to be lower but the distribution of type B was higher (P= 0.000 and P= 0.009, respectively). The prevalence of D antigen was significantly higher in diabetic people (P= 0.000).

Conclusion: In current study, blood group B was associated with type 2 diabetes, therefore, this type should be considered as a risk factor for developing diabetes; for which screening programs should be done in this community. Also, it seems that blood group genotyping could be a valuable guide in evaluating the mechanism of diabetes.