Glycated haemoglobin in diagnosis of diabetes mellitus and pre-diabetes among middle-aged and elderly population: Shanghai Changfeng study / 生物医学与环境科学（英文）

ABSTRACT

<p><b>OBJECTIVE</b>To investigate the optimal glycated haemoglobin (HbA1c) cut off points and evaluate the impact of HbA1c on diabetes and pre-diabetes in middle-aged and elderly population.</p><p><b>METHODS</b>Subjects were recruited from Shanghai Changfeng Study. A total of 1973 community-based participants (age ⋝45) without known diabetes underwent oral glucose tolerance test (OGTT) by using a 75-g oral glucose load and HbA1c was measured by using high performance liquid chromatography (HPLC). Subjects were classified as normal glucose tolerance (NGT), pre-diabetes(impaired glucose regulation, IGR) and new diagnosed diabetes (NDD) per 1999 WHO criteria. Two tests are compared with receiver operating characteristic curve (ROC).</p><p><b>RESULTS</b>Among 1973 subjects, 271 (13.7%) were diagnosed as NDD and 474 (24.0%) as IGR by using OGTT. HbA1c was 5.7%±0.7% in this population. Use of 6.5% as the HbA1C cutoff point has sensitivity of 38.7% and specificity of 98.5%. We recommend 6.0% as a better cutoff value for diagnosis of diabetes in this population (AUC 0.829, 95% CI 0.798-0.860, P<0.001) with its sensitivity and specificity as 66.1% and 86.8%. For IGR, the results showed low sensitivity (44.9%) and specificity (66.7%) with an AUC of 0.571 for HbA1c when 5.8% was used as the cutoff point. Participants detected with HbA1c⋝6.0% were associated with nearly the same metabolic characteristics, including body mass index (BMI), blood pressure, lipid profile and urine albumin-creatinine ratio (uACR) compared with diabetic subjects detected by OGTT.</p><p><b>CONCLUSION</b>The optimum HbA1c cutoff point for diabetes in our study population was lower than ADA criteria, and HbA1c may not be used to identify IGR.</p>