Cutoff value of HbA1c for predicting diabetes and prediabetes in a Chinese high risk population aged over 45

Objective: To evaluate the cutoff value of HbA1c for predicting diabetes and prediabetes in a Chinese high risk population aged over 45. Methods: A total of 619 people aged over 45 without diabetes were randomly recruited to complete the Finnish Diabetes Risk Score (FINDRISC) questionnaire. 208 high-risk individuals (defined by Diabetes Risk Score >= 9) had OGTT and HbA1c determined at the same time. Results: In a Chinese population aged over 45, the best cutoff values of HbA1c for detecting diabetes and prediabetes were 5.8% and 5.4% respectively. The area under the receiver operating characteristic (AUROC) curve of HbA1c for detecting diabetes was 0.85 (95% CI: 0.80-0.90) and prediabetes was 0.62 (95% CI: 0.54-0.70). The combined use of HbA1c and fasting blood glucose (FPG) had a larger AUROC than HbA1c alone (0.88, 95%CI: 0.83-0.92 in detecting diabetes vs 0.75, 95% CI: 0.67-0.82 in prediabetes), and had a higher sensitivity in predicting diabetes and higher specificity and positive predictive value (PPV) in predicting prediabetes. However, the AUROC between HUA1c alone and combined use in predicting diabetes was not significantly different (p=0.173). Conclusions: FINDRISC is a feasible tool to screen people who are at high risk of diabetes. The cutoff values of HbA1c to diagnose diabetes and prediabetes in a Chinese high risk population aged over 45 were 5.8% and 5.4%, respectively. The sensitivity and specificity of HbA1c for detecting diabetes and prediabetes were relatively low, so that the combined use of HbA1c and FPG may be more effective in prediction.