One-hour plasma glucose identifies metabolic subgroups in individuals with HbA1c-defined prediabetes and normal fasting and 2-hour glucose

Q: What are the key findings of this study?

Elevated 1-hour plasma glucose (≥8.6 mmol/L) identified significantly lower β-cell function (disposition index 40.47 vs 85.19, p<0.001) in adults with HbA1c-defined prediabetes but normal OGTT.

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: HbA1c-defined prediabetes and normal fasting and 2-hour glucose (n=8537). Intervention: 1-hour plasma glucose ≥8.6 mmol/L vs. 1-hour plasma glucose <8.6 mmol/L. Primary outcome: β-cell function (disposition index) (β = -0.223, 95% CI -0.227 to -0.219, p=<0.001).

Q: What does this research mean for the field?

Among individuals with HbA1c-defined prediabetes but normal fasting and 2-hour glucose, a 1-hour plasma glucose test identifies distinct subgroups with significantly different β-cell function and metabolic profiles. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Q: What question did this study set out to answer?

To evaluate whether one-hour postload plasma glucose distinguishes metabolic subgroups and beta-cell function among individuals with HbA1c-defined prediabetes who have normal fasting and two-hour glucose levels.

Ling Ouyang; Qianwen Nie; Youyuan Huang; Qiu Xue; Aimei Dong

doi:10.1186/s12902-026-02485-7

August 20, 2026BMC Endocrine DisordersOpen Access

One-hour plasma glucose identifies metabolic subgroups in individuals with HbA1c-defined prediabetes and normal fasting and 2-hour glucose

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Key result

Elevated 1-hour glucose linked to ~52% lower β-cell function in HbA1c-defined prediabetes.

β = -0.223
95% CI -0.227 to -0.219
P<0.001
n=8,537

Why the study?

Does 1-hour postload plasma glucose identify distinct metabolic subgroups with differing β-cell function among adults with HbA1c-defined prediabetes and normal fasting/2-hour glucose?

Key Points

To evaluate whether one-hour postload plasma glucose distinguishes metabolic subgroups and beta-cell function among individuals with HbA1c-defined prediabetes who have normal fasting and two-hour glucose levels.
Analyzed cross-sectional data from 8,537 Chinese adults undergoing a standard 75-g oral glucose tolerance test and HbA1c measurement.
Stratified non-diabetic participants into glycemic phenotypes based on HbA1c (≥5.7%) and oral glucose tolerance test criteria, isolating an HbA1c+/OGTT− discordant subgroup (n=922).
Further classified the discordant subgroup using a one-hour plasma glucose cutoff of 8.6 mmol/L and evaluated beta-cell function using the disposition index and linear mixed-effects models.
Among 3,800 participants with prediabetes, 24.3% had isolated HbA1c elevation (HbA1c+/OGTT−), and 51.8% of this discordant cohort exhibited elevated one-hour plasma glucose (≥8.6 mmol/L).
Individuals with one-hour plasma glucose ≥8.6 mmol/L had reduced beta-cell function (disposition index = 40.47), delayed glucose peaks at 60 minutes, impaired early-phase insulin secretion, and higher overall glycemic exposure.
Individuals with one-hour plasma glucose <8.6 mmol/L maintained preserved or enhanced beta-cell function compared to normal glucose tolerance controls (disposition index = 85.19 vs. 75.56, P < 0.001).

Study Design

Type

Cross-Sectional (n=8,537)

Multicenter

No

Structured PICO

Does 1-hour postload plasma glucose identify distinct metabolic subgroups with differing β-cell function among adults with HbA1c-defined prediabetes and normal fasting/2-hour glucose?

P

Population

8,537 Chinese adults without known diabetes, median age 55 years, undergoing standard 75-g OGTT and HbA1c testing to evaluate metabolic phenotypes.

E

Exposure

Elevated 1-hour plasma glucose (1-h PG) ≥8.6 mmol/L during a 75-g OGTT

C

Comparator

Normal 1-hour plasma glucose (1-h PG) <8.6 mmol/L during a 75-g OGTT

O

Outcome

β-cell function assessed using the disposition index (DI)surrogate

Main Result

Effect estimate: β = -0.223 (95% CI -0.227 to -0.219)

Absolute Event Rate: 40.47% vs 85.19%

p-value: p=<0.001

Limitations

Cross-sectional design precludes assessment of temporal relationships and progression to diabetes
Population consisted of individuals referred for metabolic evaluation and may not be fully representative of the general population
Information regarding haemoglobinopathies, including thalassaemia, was unavailable
Anthropometric variables and cardiovascular risk factors were not consistently available
Repeat OGTT measurements were unavailable, preventing direct assessment of the reproducibility of 1-h PG
Study population may not be fully representative of the general population
Repeat OGTT measurements were unavailable

Implication

A 1-hour postload glucose ≥8.6 mmol/L effectively identifies individuals with hidden β-cell dysfunction among those with prediabetes diagnosed solely by HbA1c, highlighting the utility of 1-hour glucose for risk stratification.

Abstract

Background This study evaluated whether 1-hour postload glucose (1-h PG) identifies distinct metabolic subgroups with differing OGTT-derived β-cell function indices among Chinese adults with HbA1c-defined prediabetes and normal fasting and 2-hour glucose. Methods This cross-sectional study included 8,537 Chinese adults undergoing 75-g OGTT and HbA1c testing. Participants were stratified into four glycemic phenotypes based on HbA1c (≥5.7%) and OGTT criteria. Within the HbA1c+/OGTT− subgroup (n=922), individuals were further classified by 1-h PG (cutoff 8.6 mmol/L). β-cell function was assessed using the disposition index (DI). Linear mixed-effects models analyzed glucose and insulin dynamics. Results Among 3,800 individuals with prediabetes, 24.3% exhibited isolated HbA1c elevation (HbA1c+/OGTT−). Within this discordant subgroup, 51.8% had elevated 1-h PG (≥8.6 mmol/L). The 1-h PG+ subgroup demonstrated lower β-cell function (DI = 40.47), delayed glucose peaks (60 min), impaired early-phase insulin secretion, and greater overall glycaemic exposure, whereas the 1-h PG− subgroup exhibited preserved or enhanced β-cell function (DI = 85.19 vs. 75.56 in NGT, P < 0.001). Multivariable linear regression analysis demonstrated that 1-h PG remained significantly associated with β-cell function after adjustment for age, sex, and HbA1c. Conclusions Among individuals with HbA1c-defined prediabetes and normal Fasting and 2-Hour Glucose, 1-hour plasma glucose identifies subgroups with differing metabolic profiles and β-cell function. These findings highlight substantial metabolic heterogeneity within this population. However, given the cross-sectional design of the study, longitudinal investigations are required to determine whether these metabolic differences translate into differences in future diabetes risk and clinical outcomes. Trial registration Not applicable.

Discussion

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Cite This Study

Ouyang et al. (2026) conducted a cross-sectional in HbA1c-defined prediabetes and normal fasting and 2-hour glucose (n=8,537). 1-hour plasma glucose ≥8.6 mmol/L vs. 1-hour plasma glucose <8.6 mmol/L was evaluated on β-cell function (disposition index) (β = -0.223, 95% CI -0.227 to -0.219, p=<0.001). Elevated 1-hour plasma glucose (≥8.6 mmol/L) identified significantly lower β-cell function (disposition index 40.47 vs 85.19, p<0.001) in adults with HbA1c-defined prediabetes but normal OGTT.

synapsesocial.com/papers/6a895f0dca7ade938187d6eb https://doi.org/10.1186/s12902-026-02485-7

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One-hour plasma glucose identifies metabolic subgroups in individuals with HbA1c-defined prediabetes and normal fasting and 2-hour glucose

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

One-hour plasma glucose identifies metabolic subgroups in individuals with HbA1c-defined prediabetes and normal fasting and 2-hour glucose

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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