1-Hour Post-Load Glucose: Early Screening for High Risk of Type 2 Diabetes in Koreans with Normal Fasting Glucose

Abstract

Context: With rising the prevalence of type 2 diabetes mellitus (T2DM) and prediabetes, the importance of 1-hour post-load plasma glucose (1-h PG) for early hyperglycemia screening is emphasized.

Objective: This study investigates the utility of 1-h PG in predicting T2DM in adults with normal fasting plasma glucose (FPG) levels.

Methods: 7,504 participants were categorized into three groups: normal glucose tolerance (NGT) with 1-h PG < 155 mg/dL, NGT with 1-h PG ≥ 155 mg/dL, and impaired glucose tolerance (IGT). Insulin sensitivity and secretion indices were compared between groups at baseline, and T2DM incidence was analyzed using Cox proportional hazards models. The predictive abilities of 1-h PG and 2-hour post-load plasma glucose (2-h PG) were assessed with receiver operating characteristic analysis.

Results: At baseline, the composite insulin sensitivity index in the NGT & 1-h PG ≥ 155 mg/dL group was similarly reduced as in the IGT group (P = .076). Over a mean follow-up of 7.4 years, T2DM developed in 960 patients (12.8%). The highest risk was in the IGT group (hazard ratio [HR] 5.47), followed by the NGT & 1-h PG ≥ 155 mg/dL group (HR 2.74), compared to the NGT & 1-h PG < 155 mg/dL group. The 1-h PG level had a higher area under the curve (0.772) than other glycemic parameters, including 2-h PG.

Conclusion: Even with normal FPG, a 1-h PG ≥ 155 mg/dL indicates lower insulin sensitivity similar to IGT and increased T2DM risk, making it a more effective early screening tool than 2-h PG.

Keywords: Glucose tolerance test; Impaired glucose tolerance; Insulin sensitivity; Post-load plasma glucose; Prediabetes; Type 2 diabetes mellitus.