老年人群糖化血红蛋白用于诊断糖调节异常的可行性研究

目的探讨老年人群中糖化血红蛋白（HbA1c）诊断糖尿病（DM）和糖调节异常（IGR）的理想切点及可行性。方法对北京万寿路社区老年人群（≥60岁）进行横断面流行病学调查,其中1 674人无糖尿病者行口服75g葡萄糖耐量试验（OGTT）,测定空腹血糖、2h血糖及HbA1c。采用受试者工作特征曲线（ROC曲线）进行判断,以OGTT诊断DM及IGR时的HbA1c值计算最佳切点。并与美国糖尿病协会（ADA）的糖尿病HbA1c诊断标准比较。结果按照1999年WHO的DM诊断标准,本研究人群中糖耐量正常（NGT）894例,空腹血糖受损（IFG）53例,糖耐量低减（IGT）369例,合并IFG＋IGT 87例,新诊断糖尿病（NDDM）271例。采用ROC曲线判断与OGTT诊断DM状态相关的HbA1c理想切点为5.9%,敏感性和特异性分别为80.1%和73.8%,曲线下面积0.832（95%CI 0.802-0.862）;与IGR状态相关的HbA1c理想切点为5.7%,敏感性和特异性分别为64.3%,60.9%,曲线下面积0.668（95%CI 0.638-0.698）。HbA1c≥5.9%作为糖尿病诊断标准与OGTT的符合率达75%,可确诊80.1%的NDDM（217例）,但包括17.3%的NGT（155例）和41.7%的IGR（212例）。按ADA HbA1c≥6.5%的标准,NDDM中的检出率只有39.1%（106例）,而特异性高仅涉及0.9%的NGT（8例）及4.5%的IGR（23例）。结论 HbA1c≥5.9%时应进一步行OGTT以明确是否患有糖尿病,≥6.5%时诊断糖尿病的特异性达到97.8%。HbA1c不适用于筛查IGR人群。

Diagnosis of type 2 diabetes mellitus and impaired glucose regulation with glycosylated hemoglobin A1c in the elderly

Objective To study the feasibility of using the optimal cut points of glycosyted hemoglobin A1c（HbA1c） in diagnosis of type 2 diabetes mellitus（DM） and impaired glucose regulation in the elderly.Methods Cross-sectional epidemiology of the elderly（age≥60 years） in Wanshou Road Community of Beijing was investigated in 2009.Oral glucose tolerance test（OGTT） was performed in 1 674 participants without known DM to measure their fasting blood glucose,2h glucose and HbA1C levels.Values of the optimal HbA1c cut points were calculated and compared with the ADA diagnostic criteria for DM when DM and IGR were diagnosed OGTT.Results Of the 1 674 participants,894 had normal glucose tolerance（NGT）,53 had impaired fasting glucose（IFG）,369 had impaired glucose tolerance（IGT）,87 had IFG and IGT,and 271 had newly diagnosed diabetes（NDD） according to the 1999 WHO diagnostic criteria.The ideal HbA1c cut point value was 5.9% when DM was diagnosed with ROC curve and OGTT,with a sensitivity of 80.1%,a specificity of 73.8%,and an area under the ROC curve of 0.832（95% CI=0.802-0.862）,and 5.7% when IGR was diagnosed with ROC curve and OGTT,with a sensitivity of 64.3%,a specificity of 60.9%,and an area under the ROC curve of 0.668（95% CI=0.638-0.698）.The Compliance rate of ROC curve and OGTT was 75%,17.3% and 41.7%,respectively,for NDDM,NGT and IGR,with a specificity of 80.1%.The diagnosis rate was 39.1%,0.9% and 4.5%,respectively,for NDDM,NGT and IGR following the ADA criteria at a HbA1c cut point≥5.9%.Conclusion OGTT should be performed to conform the diagnosis of DM when the HbA1c is≥5.9%,with a specificity of 97.8%.However,HbA1c should not be used in screening for IGR.