Enhanced Predictive Capability of a 1-Hour Oral Glucose Tolerance Test: A Prospective Population-Based Cohort Study

Abstract

OBJECTIVETo examine whether the 1-h blood glucose measurement would be a more suitable screening tool for assessing the risk of diabetes and its complications than the 2-h measurement. RESEARCH DESIGN AND METHODSWe conducted a prospective population-based cohort study of 4,867 men, randomly selected from prespecified birth cohorts between 1921 and 1949, who underwent an oral glucose tolerance test with blood glucose measurements at 0, 1, and 2 h. Subjects were followed for up to 39 years, with registry-based recording of events. Discriminative abilities of elevated 1-h ( ‡8.6 mmol/L) versus 2-h ( ‡7.8 mmol/L) glucose for predicting incident type 2 diabetes, vascular complications, and mortality were compared using Kaplan-Meier analysis, Cox proportional hazards regression, and net reclassification improvement. ), 636 (13%) developed type 2 diabetes. Elevated 1-h glucose was associated with incident diabetes (hazard ratio 3.40 [95% CI 2.90-3.98], P < 0.001) and provided better risk assessment than impaired glucose tolerance (Harrell concordance index 0.637 vs. 0.511, P < 0.001). Addition of a 1-h measurement in subjects stratified by fasting glucose provided greater net reclassification improvement than the addition of a 2-h measurement (0.214 vs. 0.016, respectively). Finally, the 1-h glucose was significantly associated with vascular complications and mortality. RESULTS Median age was 48 years (interquartile range [IQR] 48-49). During follow-up (median 33 years CONCLUSIONSThe 1-h blood glucose level is a stronger predictor of future type 2 diabetes than the 2-h level and is associated with diabetes complications and mortality.Type 2 diabetes is associated with significant morbidity and mortality and represents a major burden on health care systems worldwide (1,2). Several randomized clinical trials provide evidence that type 2 diabetes can be prevented or at least postponed with lifestyle modification and drug therapy, which makes identifying high-risk individuals particularly important (3-6). Traditionally, prediabetes has been defined as impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) during a 2-h oral glucose tolerance test (OGTT), and interventional studies thus far have predominantly included subjects with IGT (7,8). However, not all subjects with prediabetes develop type 2

One‐hour post‐load plasma glucose predicts progression to prediabetes in a multi‐ethnic cohort of obese youths

“…Thereafter, elevated 1hPG has been consistently reported to be associated with impaired insulin sensitivity, reduced β‐cell function and a less favourable cardiometabolic risk profile . Furthermore, the predictive power of 1hPG has been confirmed in large cohorts of adults from different ethnic populations …”

“…In adults, several longitudinal studies have recently identified 1‐hour post‐load glucose concentration (1hPG) during an oral glucose tolerance test (OGTT) as an earlier and more accurate predictor of diabetes than currently used biomarkers . In 2007, Abdul‐Ghani et al found that the area under the ROC curve for 1hPG to predict future diabetes is significantly greater than that of fasting and 2‐hour plasma glucose.…”

β-Cell secretory defects are present in pancreatic insufficient cystic fibrosis with 1-hour oral glucose tolerance test glucose ≥155 mg/dL

“…We have recently reported impaired β‐cell secretory capacity even in the setting of PI‐CF and normal glucose tolerance (NGT), defined using the 1‐hour OGTT glucose <200 mg/dL, compared to pancreatic sufficient CF (PS‐CF) and healthy control subjects . In non‐CF populations, 1‐hour OGTT glucose above a threshold as low as 155 mg/dL (8.6 mmol/L) portends increased risk of developing type 2 diabetes, greater adverse cardiovascular disease outcomes, and increased mortality, and is associated with impaired β‐cell function . In CF, higher 1‐hour glucose is associated with a 4‐to‐5‐fold increased risk for developing CFRD over the subsequent 5 years .…”

One hour post-load plasma glucose and 3 year risk of worsening fasting and 2 hour glucose tolerance in the RISC cohort

“…In a 33 year study, it was not only a better predictor of incident diabetes, but also of diabetes complications and mortality [4]. Robust evidence from the Botnia study and Malmö Prevention Project cohorts supports 1hPG as the best simple variable predicting incident type 2 diabetes, in comparison with other indices [1].…”