Wiener K, Roberts N B
Department of Chemical Pathology, North Manchester General Hospital, UK.
Diabet Med. 1998 Jul;15(7):558-63. doi: 10.1002/(SICI)1096-9136(199807)15:7<558::AID-DIA669>3.0.CO;2-Q.
HbA1c was measured by high-performance ion-exchange chromatography in 401 non-pregnant patients undergoing oral glucose tolerance tests (OGTT). All those with HbA1c>6.2% (reference range 3.8-5.5%) had diabetic OGTT (sensitivity 41%, specificity 100%). Although a fasting plasma glucose (FPG) cut-off > or =7.0 mmol l(-1), as recommended by the American Diabetes Association (ADA), had greater sensitivity (78%), false positives (12%) limited its usefulness, so more diagnostic confidence could be placed in a positive HbA1c. In agreement with the ADA, we found FPG gave only slightly lower diabetes prevalence than the OGTT, but this masked a significant number of individual discrepancies (false positives and negatives) cancelling out each other. The new ADA category of impaired fasting glucose did not correlate well with impaired glucose tolerance. HbA1c is insufficiently sensitive as a direct substitute for the OGTT. A third of subjects diabetic on OGTT had normal HbA1c values, so it cannot exclude diabetes as currently defined, but HbA1c screening could make sufficient positive diagnoses to reduce our non-pregnant OGTTs by one-fifth. If a 'risk threshold' for diabetic complications could be applied to HbA1c, it could replace the OGTT as a more pragmatic diagnostic/prognostic test.
对401例接受口服葡萄糖耐量试验（OGTT）的非妊娠患者，采用高效离子交换色谱法测定糖化血红蛋白（HbA1c）。所有HbA1c>6.2%（参考范围3.8 - 5.5%）的患者OGTT结果为糖尿病（敏感性41%，特异性100%）。尽管按照美国糖尿病协会（ADA）的建议，空腹血糖（FPG）切点≥7.0 mmol/L时敏感性更高（78%），但其假阳性率（12%）限制了其应用价值，因此HbA1c阳性结果的诊断可信度更高。与ADA一致，我们发现FPG得出的糖尿病患病率仅略低于OGTT，但这掩盖了大量相互抵消的个体差异（假阳性和假阴性）。ADA新定义的空腹血糖受损类别与糖耐量受损的相关性不佳。HbA1c作为OGTT的直接替代指标敏感性不足。三分之一OGTT诊断为糖尿病的患者HbA1c值正常，因此它不能排除目前定义的糖尿病，但HbA1c筛查可做出足够多的阳性诊断，使我们的非妊娠OGTT检查减少五分之一。如果能将糖尿病并发症的“风险阈值”应用于HbA1c，它可替代OGTT成为更实用的诊断/预后检查。
