Effective index of mass screening for diabetes mellitus.

虽然空腹血糖（FBG）在人群筛查中应用广泛，但发现餐后高血糖患者并不敏感。本研究以另一种糖尿病筛查方法糖化血红蛋白A<1c>（HbA_1<1c>）为研究对象，采用75 g口服葡萄糖耐量试验（OGTT）比较两种方法对餐后高血糖筛查的准确性，并探讨HbA_1的理想界值<1c>。既往研究表明，HbA_6的临界值为6.5%<1c>，与FBS=7.0 mmol/L的临界值相当。然而，临界点太高，因此，非常具体但不敏感。本研究通过降低HbA_1的临界值<1c>，观察糖尿病诊断准确率和归因于发现新糖尿病患者的变化。受试者为231名男性和323名女性，他们接受了所有三项测试，即，从<1c>ROC曲线分析，HbA_1的准确性<1c>并不像FBG那样随着截断点的降低而降低。当临界点为6.5%时，受试者的真阳性和真阴性比例分别为2.4%和1.1%。在研究人群中，19%的餐后高血糖患者FBG不能发现，但HbA_2却能检测到<1c>。当截断点降低到5.6%时，受试者的真阳性率和真阴性率分别为2.4%和1.1%，HbA_2可检出80%的餐后高血糖<1c>。此时，敏感性、特异性和阳性预测值分别为0.91、0.82和0.50。如果截断点降低超过5.6%，阳性预测值迅速降低，意味着降低性价比，从研究来看，HbA 1c对截断点的变化具有稳健性，因此降低截断点不会导致准确性降低。5.6%的临界点似乎是合理的，可以发现更多的餐后高血糖患者。

Although fasting blood glucose (FBG) is well-used in mass screening, it is not sensitive to find postprandial hyperglycemia patients. Focusing on another screening test for diabetes mellitus, Glycohemoglobin A_<1c> (HbA_<1c>), this study compared the accuracy of both screening tests for postprandial hyperglycemia using 75g oral glucose tolerance test (OGTT), and discussed the ideal cut off point of HbA_<1c>. Previous study reported that the cut off point of 6.5% for HbA_<1c> is as accurate as that of FBS=7.0 mmol/L. However, the cut off point is too high and therefore, very specific but not sensitive. In this study the authors lowered the cut off point of HbA_<1c> and observed the change of accuracy of diagnosis and attribution to finding new patients of diabetes mellitus. The subjects were 231 males and 323 females who underwent all three tests, i.e., FBG, HbA_<1c>, and 75g OGTT.From the analysis of the ROC curve, the accuracy of HbA_<1c> is not lowered as lowering the cut off point, unlike FBG. When the cut off point was 6.5%, the true positive and negative proportions of the subjects were 2.4% and 1.1%, respectively. In the study population, 19% of postprandial hyperglycemia who could not be found by FBG was detectable by HbA_<1c>. When the cut off point was lowered to 5.6%, the true positive and negative proportions of the subjects were 2.4% and 1.1%, respectively, and 80% of postprandial hyperglycemia could be found by HbA_<1c>. At the point, the sensitivity, the specificity, and positive predictive value were 0.91, 0.82 and 0.50, respectively. If the cut off point was lowered beyond 5.6%, positive predictive value was rapidly lowered, meaning lowering cost performance.From the study, HbA1c was robust against the change of cut off point, and therefore, lowering the cut off point did not cause of lower accuracy. The cut off point of 5.6% seemed to be reasonable to find more postprandial hyperglycemia patients.