Background: The evidence base in support of HbA_1c (glycosylated Hemoglobin) as a diagnostic test for diabetes mellitus is focused on predicting a clinical outcome, considered to be the pinnacle of the Stockholm Hierarchy applied to reference intervals and clinical decision limits. In the case of diabetes, the major outcome of interest is the long term microvascular complications for which a large body of data has been accumulated, leading to the endorsement of HbA_1c for diagnosis in many countries worldwide, with some variations in cut-offs and testing strategies.

Aims: To assess the role of Glycosylated Hemoglobin (HbA1C) measurement as a diagnostic test for Diabetes mellitus and to study the relationship of HbA1c and complications of diabetes mellitus.

Materials And Methods:The present clinical study was a prospective comparative study conducted over period of 8 months. Total 1025 diabetic patients who were having symptoms suggestive of diabetes mellitus like polyuria, polyphagia, polydypsia and easy fatigability and never been diagnosed as diabetic were examined out of them 820 were excluded from the study on the basis of exclusion criteria. Remaining 205 patients who satisfied the inclusion criteria were subjected to detailed history, thorough clinical examination, fundoscopic examination and HbA1c test.

Inclusion Criteria: Patients who were having symptoms suggestive of diabetes mellitus like polyuria, polydypsia, polyphagia and easy fatigability, and never being diagnosed as diabetic.

Exclusion criteria:Patients who were already diagnosed as diabetics were excluded from the study and Patients having various conditions leading to alternation in levels of HbA1c like altered erythropoiesis, altered hemoglobin, altered glycation.

Results:Total 1025 diabetic patients were examined out of them 820 were excluded from the study on the basis of exclusion criteria. Remaining 205 patients who satisfied the inclusion criteria were subjected to detailed history, thorough clinical examination, fundoscopic examination and HbA1c test. On the basis of HbA1c as a diagnostic test for diabetes mellitus out of total 205 patients one hundred four(50.7%) were diagnosed as diabetic and one hundred one(49.3) were non diabetic. On the basis of fasting blood sugar level as a diagnostic test for diabetes mellitus out of total 205 patients. Hundred (48.8%) were diagnosed as diabetic and one hundred five(51.2) were non diabetic. On the basis of post prandial blood sugar level  as a diagnostic test for diabetes mellitus out of total 205 patients. Eighty seven(42.4%) were diagnosed as diabetic and one hundred eighteen(57.6) were non diabetic. HbA1c is a good diagnostic test. But FBS, PPBS should also be done to have accurate diagnosis of diabetes mellitus and to avoid the under dignosis and rarely over diagnosis. In this study out of two hundred five patients fourty two (20.2%) had Diabetic retinopathy as a complication and sixty two (30.2) as neuropathy as a complication. Both of these two were highly significant complications associated with higher levels of HbA1c (p value 0.000).while out of two hundred five patients. Fourteen (20%) had diabetic ketoacidosis as a complication. which shown significant association with higher levels of HbA1c.(p value 0.001).

Conclusion:HbA1c is a good diagnostic test and better predictor of glycemia related complications.

But FBS, PPBS should also be done to have accurate diagnosis of diabetes mellitus(DM) and to avoid the under dignosis and rarely over diagnosis. 

 Diabetic retinopathy, neuropathy, DKA are the complications in DM depending upon the HbA1c level. and they have got significant correlation.