Type 1 diabetes mellitus (DM) is an autoimmune disease with chronic complications that is becoming more frequent as life expectancy of diabetics has increased owing to improved methods of detection and better management. In this study, we investigated whether the presence of autoimmunity can be used in predicting the development time of microvascular complications. Our study included 52 patients with type 1 diabetes mellitus (DM). The subjects had developed microvascular complications and they had been tested for anti-GAD (glutamic acid decarboxylase) antibodies and/or islet-cell antibodies (ICA). In the assessment of microvascular complications, we used ocular fundus examination, electromyography (EMG), and 24-h urine microalbuminuria tests. Of the patients included in the study, 30 were female and 22 were male. Of all patients characterized for the existence of diabetic complications, 36 of 52 had both diabetic retinopathy and diabetic nephropathy, 5 patients had diabetic neuropathy, and 11 patients had diabetic retinopathy only. At the diagnosis of diabetes, 20 in 52 patients tested negative for autoantibodies (anti-GAD and anti-ICA), while 32 of 52 tested positive for anti-GAD and/or anti-ICA. The mean HbA1C level of autoantibody-negative patients was 7.7%, while antibody-positive patients had slightly higher HbA1c levels (7.9%). However, this difference was not statistically significant (p>0.05). The mean development time of microvascular complications in autoantibody-positive patients was calculated as 11: 40±6.46 years, and in patients with negative autoimmunity results it was 10.91±6.70 years. The presence of diabetes-related autoantibodies (DRAs) in patients with type 1 diabetes mellitus does not have a significant effect on the development time of diabetic microvascular complications.