| Objective To study the value of glycosylated hemoglobin on diagnosis of abnormal glucose metabolism among the middle aged and elderly population in LanzhouMethods A cluster sampling study was performed choosing sample of 8871 subjects without history of diabetes in the elderly population (aged≥40 years) in Lanzhou. Questionnaire was conducted, height, weight, waist circumference, hip circumference and blood pressure were measured, waist-hip ratio, body mass index(BMI) were calculated, fasting blood glucose (FBG), postprandial blood glucose (PBG), glycosylated hemoglobin (HbAlC), high-density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) total cholesterol (CHOL), triglyceride (TG), were tested. Using OGTT test as the gold standard, to analysis the effect of glycosylated hemoglobin on screening and diagnosis of diabetes and impaired glucose regulation through drawing curves receiver operating characteristic (ROC) curve.Results 1.8,296 subjects were deemed eligible for and included in the study. Based on 1999 World Health Organization criteria, there were 4391 (52.9%) with normal glucose tolerance (NGT),1206 (14.5%) diabetes (DM), and 2699 (32.5%) impaired glucose regulation (IGR). Among 1206 diabetes, there were 232 (2.8%) with isolated fasting blood glucose diabetes(i-FBG), 569 (6.9%) postprandial blood glucose diabetes(2hPG), and 405 (4.9%) fasting blood glucose combining with postprandial blood glucose diabetes. Among2699 impaired glucose regulation, there were 423 (5.1%) with isolated impaired fasting glucose (i-IFG),1633 (19.7%) isolated impaired glucose tolerance, and 643 (7.8%) impaired fasting glucose combining with impaired glucose tolerance (IGT).2. Based on HbAlc≥6.5%recommend by ADA2010 as DM diagnosis, there were 941 patients with DM, This outcome was generally consistent with the WHO diagnostic criteria (Kappa value=0.465). Applying the HbAlc≥6.5%for diagnosing diabetes, its sensitivity, specificity, positive predictive value and negative predicative value were 47.4%,94.8%,60.8% and 93.6%, respectively, the misdiagnosis rate is only 5.2%, the missed diagnosis was 52.6%, and the 39.2% of the patients of HbAlc≥6.5% did not meet the OGTT-DM diagnostic criteria. Applying only FPG≥7.0mmol/L as OGTT-DM diagnostic criteria, the sensitivity is only 52.8%, the missed diagnosis was 47.2%, and the consistency of diagnosing was for general (Kappa value=0.604).3. Based on HbAlc≥5.7% recommend by ADA as DM diagnosis, there were 5069 patients with IGR. The sensitivity, specificity, positive predictive value and negative predicative value of OGTT-IGR diagnosis were 79.7%,37.5%,44.0%and80.0%, Applying only FPG>6.1mmol/L as OGTT-DM diagnostic criteria, the sensitivity is only 39.5%, the missed diagnosis was 60.5%.4. According to the gold criteria of diagnosing DM by OGTT, and drawing the ROC curve, HbAlc≥6.2% and FPG≥6.1 mmol/L looked as the optimal cut-point for predicting DM, the sensitivity, specificity, positive predictive value, negative predictive value were 67.4%vs78.4%, 80.5%vs85.0%,37.0%vs47.0%,93.6%vs 95.9%,0.808vs0.902. HbAlc can be used in the screening in OGTT-DM, but the effect is not as good as FBG.5.1n using the ROC curve, the optimal cut-point of HbAlc and PFG for screening of DM were 6.15% and 5.6mmol/L, and its sensitivity, specificity, positive predictive value, negative predictive value and the area under curve (AUC) were 52.7%vs 66.8%,72.2%vs80.7%, 53.8%vs65.3%,71.3%vs79.3% and 0.664vs0.807 respectively, the effect of screening of OGTT-IGR FPG was better than HbA1c, and HbA1c for screening of IGR was poor in ability.6. When joint HbAlc≥6.2% or FPG≥6.1 mmol/L was for screening OGTT L-DM, the joint sensitivity was 93.0%, the missed diagnosis is only 7.0%, it was better than using only one of them and the sensitivity increased by 14.6%～25.6%;When joint HbAlc≥6.2% and FPG>6.1 mmol/L for diagnosis of DM, its joint rate of specificity was 97.1%, and the misdiagnosis rate is only 2.9%, comparing to use only of them, its specific degrees increased by 12.1%-16.6%;when joint HbAlc≥6.5% and FPG>6.1 mmol/L, the joint specific degrees up to 99.1%, the misdiagnosis rate of less than 1%.7. When joint HbAlc≥6.0% or FPG>5.6mmol/L for screening OGTT L-IGR, its joint sensitivity is as high as 93.3%, comparing to use only one of them, its sensitivity increased by 26.5-41.2%; When joint HbA1c≥6.0% and FPG≥5.6mmol/L, its joint rate of specificity reached 94.6%, the misdiagnosis rate is only 5.4%, comparing to only use HbA1≥6.2%, its specific degrees increased by 13.9%～22.4%.8. According to OGTT diagnostic criteria, compared to female crowd, the male crowd’s optimal cut points of HbA1c for screening OGTT-DM was bigger (6.2%vs6.1%); Using HbA1c for screening DM optimal cut points of People over the age of 50 higher than 40-49 people (6.2%vs6.1%). Using HbA 1 c for diagnosing DM has BMI specificity, the optimal cut points of HbAlc had the rising trend when BMI was increased, but the sensitivity and specificity was not declined.Conclusion HbAlc can be used to diagnosis of DM in the Gansu province, HbAl c may not apply to Screen IGT group. The effect of FPG was best in screening and diagnosing DM and IGR, It showed that blood glucose was more suitable for using diagnose of DM and IGR than HbA1c among the middle aged and elderly population in Lanzhou. Joint application of HbAlc and FPG could obtain higher sensitivity and specificity, reduced missed diagnosis and misdiagnosis rate, improved the effect of early diagnosis. |
PDF Full Text Request