Validity of glycated hemoglobin in screening and diagnosing type 2 diabetes mellitus in Chinese subjects

Abstract

Background/aims: The application of glycated hemoglobin (HbA(1c)) for the diagnosis of diabetes is currently under extensive discussion. In this study, we explored the validity of using HbA(1c) as a screening and diagnostic test in Chinese subjects recruited in Nanjing, China.

Methods: In total, 497 subjects (361 men and 136 women) with fasting plasma glucose (PG) ≥ 5.6 mmol/L were recruited to undergo the oral glucose tolerance test (OGTT) and HbA(1c) test. Plasma lipid, uric acid, and blood pressure were also measured.

Results: Using a receiver operating characteristic curve, the optimal cutoff point of HbA(1c) related to diabetes diagnosed by the OGTT was 6.3%, with a sensitivity and specificity of 79.6% and 82.2%, respectively, and the area under the curve was 0.87 (95% confidence interval, 0.83 to 0.92). A HbA(1c) level of 6.5% had a sensitivity and specificity of 62.7% and 93.5%, respectively. When comparing the HbA(1c) ≥ 6.5% or OGTT methods for diagnosing diabetes, the former group had significantly higher HbA(1c) levels and lower levels of fasting and 2-hour PG than the latter group. No significant difference was observed in the other metabolism indexes between the two groups.

Conclusions: Our results suggest that HbA(1c) ≥ 6.5% has reasonably good specificity for diagnosing diabetes in Chinese subjects, which is in concordance with the American Diabetes Association recommendations.

Keywords: Diabetes mellitus, type 2; Diagnosis; Glucose tolerance test; Glycated hemoglobin.

Figure 1

The ROC curve for diabetes diagnosis using HbA_1c, with OGTT as the reference standard. ROC, receiver operating characteristic; HbA_1c, glycated hemoglobin; OGTT, oral glucose tolerance test; AUC, area under the curve; CI, confidence interval.