The cutoffs and performance of glycated hemoglobin for diagnosing diabetes and prediabetes in a young and middle-aged population and in an elderly population

摘要

The aims were to compare the appropriate cutoffs of glycated hemoglobin (HbA_(1c)) in a population of varying ages and to evaluate the performance of HbA_(1c) for diagnosing diabetes and prediabetes. A total of 1064 participants in the young and middle-aged group and 1671 in the elderly group were included and underwent HbA_(1c) testing and an oral glucose tolerance test (OGTT). Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated to evaluate the optimal HbA_(1c) cutoffs. Kappa coefficients were used to test for agreement between HbA_(1c) categorization and OGTT-based diagnoses. The optimal HbA_(1c) cutoffs for diagnosing diabetes were 5.7% (39 mmol/mol) in the young and middle-aged group with a sensitivity of 66.7%, specificity of 86.7%, and AUC of 0.821 (95% CI: 0.686, 0.955) and 5.9% (41 mmol/mol) in the elderly group with a sensitivity of 80.4%, specificity of 73.3%, and AUC of 0.831 (0.801,0.861). The optimal cutoffs for diagnosing prediabetes were 5.6% (38 mmol/mol) and 5.7% (39 mmol/mol) in the young and middle-aged group and in the elderly group, respectively. Agreement between the OGTT-based diagnosis of diabetes or prediabetes and the optimal HbA_(1c) cutoff was low (all kappa coefficients <0.4). The combination of HbA_(1c) and fasting plasma glucose increased diagnostic sensitivities or specificities. In conclusion, age-specific HbA_(1c) cutoffs for diagnosing diabetes or prediabetes were appropriate. Furthermore, the performance of HbA_(1c) for diagnosing diabetes and prediabetes was poor. HbA_(1c) should be used in combination with traditional glucose criteria when detecting and diagnosing diabetes or prediabetes.