This study investigated the value of HbA1c as a screening and diagnostic test for diabetes mellitus (DM) in high-risk Turkish individuals. Materials and methods: A total of 295 participants were successfully screened. Patients were divided into 4 groups based on their oral glucose tolerance test results, according to criteria put forth by the American Diabetes Association; 120 (40.7%) had normoglycemia, 44 (14.9%) had DM, 62 (21%) had impaired fasting glucose, and 69 (23.4%) had impaired glucose tolerance. Results: With a cut-off value for the diagnosis of DM of 6.1%, HbA1c had a sensitivity of 81.8% and a specificity of 80%, with positive and negative predictive values of 80.2% and 81.05%, respectively. A sensitivity of 56.8% and a specificity of 89.2% were calculated for a cut-off value of 6.5%. Both fasting plasma glucose and 2-h plasma glucose levels were found to correlate moderately with HbA1c levels (r = 0.47, P = 0.001 and r = 0.52, P = 0.000, respectively). Conclusion: The results of our observations suggest that HbA1c could be used to make a diagnosis of DM in the Turkish population. However, further studies are needed to determine the most accurate cut-off value. Standardization of HbA1c assays used worldwide is also of great importance.

This study investigated the value of HbA1c as a screening and diagnostic test for diabetes mellitus (DM) in high-risk Turkish individuals. Materials and methods: A total of 295 participants were successfully screened. Patients were divided into 4 groups based on their oral glucose tolerance test results, according to criteria put forth by the American Diabetes Association; 120 (40.7%) had normoglycemia, 44 (14.9%) had DM, 62 (21%) had impaired fasting glucose, and 69 (23.4%) had impaired glucose tolerance. Results: With a cut-off value for the diagnosis of DM of 6.1%, HbA1c had a sensitivity of 81.8% and a specificity of 80%, with positive and negative predictive values of 80.2% and 81.05%, respectively. A sensitivity of 56.8% and a specificity of 89.2% were calculated for a cut-off value of 6.5%. Both fasting plasma glucose and 2-h plasma glucose levels were found to correlate moderately with HbA1c levels (r = 0.47, P = 0.001 and r = 0.52, P = 0.000, respectively). Conclusion: The results of our observations suggest that HbA1c could be used to make a diagnosis of DM in the Turkish population. However, further studies are needed to determine the most accurate cut-off value. Standardization of HbA1c assays used worldwide is also of great importance.