AimsBecause one-hour post-load plasma glucose (1 h-PG) ≥ 155 mg/dL (8.6 mmol/L) has been proposed as an early marker for future diabetes but lacks sufficient longitudinal confirmation of its risk, we aimed to evaluate the risk of T2D based on 1 h-PG and track changes of insulin sensitivity and β-cell function over time by 1 h-PG in a longitudinal cohort. MethodsOGTTs were conducted every 2 years in the 10-year longitudinal Korean Genome Epidemiology study (n = 6144) with three groups characterized at baseline: Low 1 h-PG (< 155 mg/dL) with Normal Glucose Tolerance (NGT), High 1 h-PG (≥155 mg/dL) with NGT, and prediabetes (PreDM). ResultsT2D risk was higher in people with High 1 h-PG with NGT and PreDM than those with Low 1 h-PG with NGT. Baseline insulin sensitivity in Low 1 h-PG as measured by the insulin sensitivity and secretion (ISS) model and Matsuda insulin sensitivity index (ISI) was higher than in High 1 h-PG, which was comparable to PreDM. β-cell function as assessed by ISS and the insulinogenic index decreased from Low 1 h-PG to High 1 h-PG to PreDM. Over time, insulin sensitivity decreased in the three groups. Time from High 1 h-PG to T2D was 0.9 years shorter than from Low 1 h-PG. All participants passed the 1 h-PG threshold for T2D (209 mg/dL, 11.6 mmol/L) first, and 74 % passed the 1 h-PG threshold for impaired glucose tolerance (IGT; 155 mg/dL) first. ConclusionsHigh 1 h-PG NGT is an intermediate risk category between Low 1 h-PG NGT and PreDM and may provide an opportunity for early intervention to prese rve ß-cell function.
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