Accuracy of 1-hour plasma glucose in diagnosing intermediate hyperglycaemia and diabetes in adults

Abstract

Background: One-hour plasma glucose during a 75-g oral glucose tolerance test may detect dysglycaemia earlier than fasting or two-hour glucose, but its diagnostic performance has not been adequately evaluated in Bangladeshi adults.

Objectives: To assess the diagnostic accuracy of one-hour plasma glucose for detecting intermediate hyperglycaemia and diabetes in adults, using the conventional fasting and two-hour oral glucose tolerance test as the reference standard

Methods: This cross-sectional observational study was conducted at the Department of Endocrinology, Bangladesh Medical University, Dhaka, from January 2025 to January 2026. Adults without known diabetes or intermediate hyperglycaemia were enrolled by non-probability consecutive sampling. Following written consent, participants underwent a 75-g oral glucose tolerance test with fasting, one-hour, and two-hour plasma glucose measurements. Reference diagnoses followed World Health Organization criteria; one-hour thresholds were 8.6-11.5 mmol/L for intermediate hyperglycaemia and ≥11.6 mmol/L for diabetes, according to International Diabetes Federation criteria. Diagnostic performance and agreement were calculated in SPSS.

Results: Among 610 adults, mean body mass index was 26.7 kg/m², and 377 (61.8%) had obesity. For intermediate hyperglycaemia, one-hour plasma glucose showed 64.7% sensitivity, 70.9% specificity, 43.3% positive predictive value, 85.4% negative predictive value, and 69.3% accuracy. For diabetes, sensitivity was 89.3%, specificity 91.4%, positive predictive value 59.3%, negative predictive value 98.4%, and accuracy 91.1%. Agreement across normal glucose tolerance, intermediate hyperglycaemia, and diabetes was moderate (Cohen's kappa 0.47). Compared with the reference test, one-hour plasma glucose classified more participants as having intermediate hyperglycaemia or diabetes.

Conclusions: One-hour plasma glucose demonstrated high sensitivity and specificity for diabetes but modest accuracy for intermediate hyperglycaemia. Its high negative predictive value may support earlier exclusion of diabetes; however, positive results should be confirmed using standard diagnostic criteria.

[J Assoc Clin Endocrinol Diabetol Bangladesh, 2026;5(Suppl 1): S42]