One-Hour Oral Glucose Tolerance Tests For The Prediction And Diagnostic Surveillance Of Type 1 Diabetes

Context: Once islet autoantibody-positive individuals are identified, predicting which individuals are at highest risk for type 1 diabetes (T1D) is important. A metabolic risk score derived from 2-hour oral glucose tolerance test (OGTT) data, the Diabetes Prevention Trial-Type 1 risk score (DPTRS), can accurately predictT1D. However, 2-hour OGTTs are time-consuming and costly.Objective: We aimed to determine whether a risk score derived from 1-hour OGTT data can predictT1D as accurately as the DPTRS. Secondarily, we evaluated whether a 1-hour glucose value can be used for diagnostic surveillance.Methods: The DPTRS was modified to derive a 1-hour OGTT risk score (DPTRS60) using fasting C-peptide, 1-hour glucose and C-peptide, age, and body mass index. Areas under receiver operating curves (ROCAUCs) were used to compare prediction accuracies of DPTRS60 with DPTRS in Diabetes Prevention Trial-Type 1 (DPT-1) (n = 654) andTrialNet Pathway to Prevention (TNPTP) (n = 4610) participants. Negative predictive values (NPV) for T1D diagnosis were derived for 1-hour glucose thresholds.Results: ROCAUCs forT1D prediction 5 years from baseline were similar between DPTRS60 and DPTRS (DPT-1: 0.805 and 0.794; TNPTP: 0.832 and 0.847, respectively). DPTRS60 predicted T1D significantly better than 2-hour glucose (P < .001 in both cohorts). A 1-hour glucose of less than 180 mg/dL had a similar NPV, positive predictive value, and specificity forT1D development before the next 6-month visit as the standard 2-hour threshold of less than 140 mg/dL (both >= 98.5%).Conclusion: A 1-hour OGTT can predictT1D as accurately as a 2-hour OGTT with minimal risk of missing a T1D diagnosis before the next visit.