Objective: The objective of this study is to determine the diagnostic threshold of HbA1c for diabetes and the impact of using it on diabetes prevalence.
Methods: A population-based stratified study was conducted in 2010 among community-dwelling adults aged ≥35years in southern China. Participants without previously-diagnosed diabetes (PDD) took oral glucose tolerance test (OGTT) and HbA1c assay. HbA1c diagnostic threshold was determined by receiver operating characteristic curve.
Results: A total of 6989 participants with mean age of 52years were recruited. The area under curve of HbA1c was 0.903 (95% CI: 0.883-0.922), with optimal cut-off value at 6.25% (sensitivity 75.6% and specificity 91.9%). There were 449 (6.42%) patients with PDD and 422 (6.04%), 815 (11.66%) and 918 (13.13%) new cases diagnosed by OGTT, HbA1c ≥6.25% or either, respectively. When either HbA1c or OGTT was used, newly-diagnosed diabetes prevalence increased by 117.4%.
Conclusions: Diabetes is prevalent in southern China. Near half of the patients go undetected with current diagnostic criteria. HbA1c ≥6.25% may be the diagnostic threshold value but needs further verification. The introduction of HbA1c threshold into diabetes diagnosis in China will cause a substantial increase in diabetes prevalence and great challenge on the public healthcare system.
Keywords: 2-hour plasma glucose; 2h-PG; AUC; BMI; CHD; DBP; Diabetes mellitus; Diagnosis; FPG; HDL-C; Hemoglobin A1c; LDL-C; NDD; NPV; OGTT; PDD; PPV; Public health; ROC; SBP; Southern China; TC; Threshold value; WHR; areas under the curve; body mass index; coronary heart disease; diastolic blood pressure; fasting plasma glucose; high density lipoprotein cholesterol; low density lipoprotein cholesterol; negative predictive value; newly-detected diabetes; oral glucose tolerance test; positive predictive value; previously-diagnosed diabetes; receiver operating characteristic; systolic blood pressure; total cholesterol; waist–hip ratio.
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