本帖最後由 lsc0019 於 2009-9-17 00:06 編輯
作者：Laurie Barclay, MD
出處：WebMD醫學新聞
August 28, 2009 — 根據一項發表於8月號小兒醫學期刊的研究結果，血紅素A1c（HbA1c）與1,5-anhydroglucitol血液檢查可能加速肥胖青少年第二型糖尿病篩檢。
來自達拉斯德州大學西南醫學中心的Shuchi Shan醫師與其同事們表示，簡易地對兒童實施T2DM（第二型糖尿病）篩檢，將可以加速早期介入速度。雖然成人必須接受至少三種這樣的檢查（空腹血糖、HbA1c與1,5-anhydroglucitol），但是這些檢查尚未系統性地在肥胖兒童身上進行比較。
在一項大型兒童肥胖門診族群（共468位）中，研究者比較HbA1c、1,5-anhydroglucitol、空腹血糖與胰島素抗性評量，檢視這些檢驗在找出第二型糖尿病與葡萄糖耐受性不佳病患的效果。病患的平均身體質量指數（BMI）為34.4 kg/m2。空腹實驗室檢驗值，包括血糖、胰島素與HbA1c。在對胰島素產生抵抗性的病患中（血清空腹胰島素濃度高於15 μIU/mL），檢測1,5-anhydroglucitol的濃度。每位病患都接受口服葡萄糖測試，測量2小時後血糖與胰島素濃度。
他們也檢驗潛在可能預測超過2小時血糖臨界值的因子，包括空腹血糖、評估胰島素抵抗性體內平衡模式（HOMA-IR）、HbA1c與1,5-anhydroglucitol值。作為篩檢效果的評量，他們也畫出接受者工作特徵曲線來決定曲線下面積（AUC）。
在胰島素抵抗性組，3位病患有第二型糖尿病（2%），23位病患有葡萄糖耐受性不佳（12%）的問題。在偵測第二型糖尿病方面，最佳的敏感度與專一度，HbA1c值6.0%以上為99%與96%、1,5-anhydroglucitol濃度低於17.0 μg/mL為96%與88%。空腹血糖濃度與HOMA-IR在這些病患的敏感度與專一度較低。
在整個研究組中，9位病患有第二型糖尿病（2%）、44位病患有葡萄糖耐受性不佳（9%）的問題。在偵測第二型糖尿病方面，最佳的敏感度與專一度，HbA1c值5.7%以上為86%與85%、空腹血糖104 mg/dL為88%與93%、HOMA-IR值7.9為62%與70%。
研究作者們寫到，HbA1c、1,5-anhydroglucitol與空腹血糖都是預測肥胖兒童T2DM的良好預測因子，但是HOMA-IR值則不是。HbA1c與1,5-anhydroglucitol都是預測胰島素抵抗性肥胖兒童T2DM的絕佳預測因子。
這項研究的限制包括僅對胰島素抵抗性受試者測量1,5-anhydroglucitol濃度、試驗組第二型糖尿病病例數相對較少、以及這項研究中有關於複製到執業之篩檢效果的不確定性。
研究作者們的結論是，因為過去討論到HbA1c標準化的困難，使用目前這項研究的數據，根據在社區取得的HbA1c數值來指引治療決定，仍需特別謹慎。
研究作者們表示沒有相關資金上的往來。
Blood Tests May Facilitate Screening for Type 2 Diabetes in Obese Youth
By Laurie Barclay, MD
Medscape Medical News
August 28, 2009 — Blood tests for hemoglobin A1c (HbA1c) and 1,5-anhydroglucitol may facilitate screening for type 2 diabetes in obese youth, according to the results of a study reported in the August issue of Pediatrics.
"Easily implemented screening tests for T2DM [type 2 diabetes mellitus] in children would facilitate early intervention," write Shuchi Shah, MD, from University of Texas Southwestern Medical Center in Dallas, and colleagues. "Although at least 3 such tests have been examined in adults (fasting BG [blood glucose], HbA1c, and 1,5-anhydroglucitol), they have not been systematically compared in obese children."
In a large pediatric obesity clinic population (n = 468), the investigators compared HbA1c, 1,5-anhydroglucitol, fasting blood glucose, and a measure of insulin resistance for their efficacy in identifying patients with type 2 diabetes and impaired glucose tolerance. Mean body mass index (BMI) was 34.4 kg/m2. Fasting laboratory tests included serum glucose and insulin and HbA1c. In a subgroup of insulin-resistant patients (serum fasting insulin level > 15 μIU/mL), levels of 1,5-anhydroglucitol were also measured. Every patient had an oral glucose-tolerance test for measurement of 2-hour postload serum glucose and insulin levels.
Potential predictors for exceeding various 2-hour blood glucose cutoff values were examined, including fasting blood glucose, Homeostasis Model of Assessment for Insulin Resistance (HOMA-IR), HbA1c, and 1,5-anhydroglucitol values. As measures of screening efficacy, receiver operator characteristic curves were fitted to determine area under the curve (AUC).
In the insulin-resistant subgroup, type 2 diabetes was present in 3 patients (2%) and impaired glucose tolerance in 23 patients (12%). For detection of type 2 diabetes, optimal sensitivity and specificity were, respectively, 99% and 96% at HbA1c levels of 6.0% or more, and 96% and 88% at 1,5-anhydroglucitol levels of less than 17.0 μg/mL. Fasting blood glucose levels and the HOMA-IR were less sensitive and specific in these patients.
In the entire study group, type 2 diabetes was present in 9 patients (2%) and impaired glucose tolerance in 44 patients (9%). For detection of type 2 diabetes, optimal sensitivity and specificity were, respectively, 86% and 85% at HbA1c levels of 5.7%, 88%, and 93% at a fasting blood glucose level of 104 mg/dL and 62% and 70% at an HOMA-IR of 7.9.
"HbA1c, 1,5-anhydroglucitol, and fasting BG levels are good predictors of T2DM in obese children, whereas HOMA-IR values are not," the study authors write. "HbA1c and 1,5-anhydroglucitol are excellent predictors of T2DM in insulin-resistant obese children."
Limitations of this study include measurement of 1,5-anhydroglucitol levels only in subjects who were insulin-resistant, relatively few cases of type 2 diabetes in the study groups, and uncertainty concerning replication in practice of the screening efficacy obtained in this study.
"Because of the difficulty with standardization of HbA1c assays discussed previously, particular caution is urged in using the data in the present study to guide therapeutic decisions on the basis of HbA1c values obtained in the community," the study authors conclude.
The study authors have disclosed no relevant financial relationships.
Pediatrics. 2009;124:573-579. |
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