Background: HbA1C a marker of chronic hyperglycemia, is associated with diabetes and its complications and has been recommended as a diagnostic test. It is an indicator of average blood glucose concentration over the period of 2–3 months. Objectives:The main objective of this study was to compare the efficiency of HbA1C, fasting & post prandial blood glucose levels, in the diagnosis of type– 2 diabetes mellitus. Material and Methods: This study was conducted in Career Institute of Medical Sciences and Hospital, a tertiary care referral hospital over a period of 6 months (July 2017–December 2017). Total 300 subjects included in this study were divided into 2 groups. Results:The study and control group were almost of the similar ages. FBS & 2 hour PP of control groups are 95.5 ± 9.8 & 168.45 ± 22.8 (mg/dl) respectively & that of type 2DM is 198.5 ± 25.6 & 295.8 ± 32.6 respectively. The HbA1C % of all the 30 cases of DR & all the cases with micro–albuminuria was >7.5%. Conclusion: HbA1C can be used effectively for the diagnosis of type 2 DM & it can be used for predicting the complications of type 2 DM. It shows a direct & linear correlation with the diabetic retinopathy and micro–albuminuria. It is very safe to say that HbA1C is better parameter than FBS & 2 hour PP BS level in diagnosing & predicting the complications of diabetes.