Objective: This investigation evaluated nine metabolic indexes from IVGTT and OGTT in an effort to determine their prognostic performance in predicting the development of type 1 diabetes in those with moderate risk, as defined by familial relation to a type 1 diabetic, a positive test for islet cell antibodies (ICA) and insulin autoantibody (IAA), but with normal glucose tolerance.
Research Design and Methods: Subjects (n = 186) who had a projected risk of 25 – 50% for developing type 1 diabetes within 5 years were followed until clinical diabetes onset or the end of the study as part of the Diabetes Prevention Trial–Type 1. Prognostic performance of the metabolic indexes was determined using receiver operating characteristic (ROC) curve and survival analyses.
Results: Two-hour glucose from OGTT most accurately predicted progression to disease compared to all other metabolic indicators with an area under the ROC curve of 0.67 (0.59-0.76), closely followed by FPIR/HOMAR-IR with an AUC value of 0.66. The optimal cut-off value for two-hour glucose (114 mg/dl) maintained sensitivity and specificity values > 0.60. The hazard ratio for those with two-hour glucose ≥ 114 mg/dl compared to those < 114 mg/dl was 2.96 (1.67-5.22).
Conclusions: FPIR/HOMA-IR from IVGTT provided similar accuracy in predicting the development of type 1 diabetes as two-hour glucose from OGTT, which due to lower cost is preferred. The optimal cut-off value determined for two-hour glucose provides additional guidance for clinicians to identify subjects for potential prevention treatments before the onset of the impaired glucose tolerance.
- Received April 29, 2010.
- Accepted August 21, 2010.
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