Exploration and Validation of the Performance of Hemoglobin A1c in Detecting Diabetes in Community-Dwellers With Hypertension

BACKGROUND: Diabetes can complicate hypertension management by increasing the risk of cardiovascular disease (CVD) and all-cause mortality. Studies targeting diabetes detection in hypertensive individuals demonstrating an increased risk of diabetes are lacking. We aimed to assess the performance of hemoglobin A(1c) (HbA(1c)) and its cut-off point in detecting diabetes in the abovementioned population. METHODS: Data from 4,096 community-dwellers with hypertension but without known diabetes were obtained from the Study on Evaluation of iNnovated Screening tools and determInation of optimal diagnostic cut-off points for type 2 diaBetes in Chinese muLti-Ethnic (SENSIBLE) study; these data were randomly split into exploration (70% of the sample) and internal validation (the remaining 30%) datasets. The optimal HbA(1c) cut-off point was derived from the exploration dataset and externally validated using another dataset from 2,431 hypertensive individuals. The oral glucose tolerance test was considered the gold-standard for confirming diabetes. RESULTS: The areas under the ROC curves for HbA(1c) to detect diabetes were 0.842, 0.832, and 0.829 for the exploration, internal validation, and external validation datasets, respectively. An optimal HbA(1c) cut-off point of 5.8% (40 mmol/mol) yielded a sensitivity of 76.2% and a specificity of 74.5%. Individuals who were not diagnosed as having diabetes by HbA(1c) at 5.8% (40 mmol/mol) had a lower 10-year CVD risk score than those diagnosed as having diabetes (P=0.01). HbA(1c)≤5.1% (32 mmol/mol) and ≥6.4% (46 mmol/mol) could indicate the absence and presence of diabetes, respectively. CONCLUSIONS: HbA(1c) could detect diabetes effectively in community-dwellers with hypertension.