Objective: To estimate the prevalence of islet cells autoantibodies among non-diabetic relatives of type 1 and type 2 diabetic patients. Methods: The study was conducted at the College of Medicinal Technology, Basra, Iraq, from December 2010 to December 2012, and comprised both diabetics and non-diabetics. The participants were first divided into two groups: type 1 diabetics; and type 2 diabetics. Both the groups had 2 sub-groups each; their non-diabetic relatives and non-relatives as controls. Laboratory investigations were done to estimate glutamic acid decarboxylase and islet cell antigen-2 autoantibodies by enzyme-linked immunosorbent assay for all groups. Significant differences were assessed with chi-square test. Results: Of the 300 subjects, 100(33.3%) were diabetics and 200(66.6%) non-diabetics. Among diabetics, 40(40%) had type 1 while 60(60%) had type 2 diabetes. Among type 1 diabetics, 27(67.5%) tested positive for glutamic acid decarboxylase autoantibodies compared to 15(25%) in type 2 diabetics, 6(15%) among relatives of type 1, 7(11.7%) among relatives of type 2 diabetic patients, and none among controls. Besides, 16(40%) of type 1 diabetic patients tested positive for islet cell antigen-2 autoantibodies compared to 8(13.3%) in type 2, and none in the sub-groups. Conclusion: The relatives of both types of diabetic patients showed immunity to islet cell autoantibodies which confirmed the effect of genetic factors in disease pathogenesis and may be important in disease prediction.