Enzymatic 2-Hydroxybutyrate Assay: A Novel Screening Tool to Detect Dysglycemia Beyond Standard Fasting Tests

Highlight

This study introduces a novel enzymatic assay (XpressGT) for measuring fasting 2-hydroxybutyrate (2-HB) as a sensitive biomarker to detect dysglycemia beyond conventional fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) measurements. 2-HB levels increase significantly from normoglycemia to prediabetes and type 2 diabetes, showing strong association with postprandial hyperglycemia despite normal fasting parameters. The assay demonstrated high diagnostic performance, achieving an area under the receiver operating characteristic curve (AUC) of 0.79, with 90% sensitivity and 98.9% negative predictive value for ruling out dysglycemia. These findings suggest enzymatic 2-HB measurement could serve as a noninvasive, cost-effective screening tool for early dysglycemia detection in patients who would otherwise be missed by standard fasting tests.

Study Background

Dysglycemia, encompassing impaired glucose tolerance and early stage type 2 diabetes mellitus (T2DM), poses a substantial and growing global health burden. Early identification of dysglycemia is critical for timely intervention to prevent progression and associated complications. Conventional screening relies heavily on fasting plasma glucose and HbA1c measurements, which do not robustly capture postprandial glucose excursions. Oral glucose tolerance testing (OGTT), the gold standard for detecting postprandial dysglycemia, is labor-intensive and inconvenient for widespread screening. Thus, there is an unmet need for simple, reliable biomarkers that effectively identify dysglycemia, especially in individuals with normal fasting glucose and HbA1c values.

Metabolomic studies have identified 2-hydroxybutyrate (2-HB), a byproduct of amino acid catabolism and oxidative stress, as a promising candidate biomarker linked to insulin resistance and glucose metabolism disturbances. However, measuring 2-HB traditionally requires laborious methods like liquid chromatography-mass spectrometry, limiting clinical applicability. The development of a rapid enzymatic assay for 2-HB presents an opportunity to translate this biomarker into practical clinical use.

Study Design

The investigation was conducted using samples from the Biomarkers of Personalized Medicine cohort comprising 772 individuals assessed for glycemic status. The study focused on fasting 2-HB levels measured by the novel enzymatic XpressGT assay. A prespecified subcohort of 534 individuals with normal fasting plasma glucose (<110 mg/dL) and HbA1c (140 mg/dL during OGTT.

Associations between 2-HB concentrations and glycemic categories (normoglycemia, prediabetes, and type 2 diabetes) were assessed. Diagnostic performance metrics, including area under the curve (AUC), sensitivity, and negative predictive value, were calculated to determine assay utility in detecting dysglycemia in subjects with normal fasting parameters. Logistic regression analyses adjusted for confounders evaluated the independent association of 2-HB with dysglycemia.

Key Findings

Fasting 2-HB levels demonstrated a stepwise increase across glycemic categories: normoglycemia (39.0 µmol/L), prediabetes (51.9 µmol/L), and type 2 diabetes (57.0 µmol/L), indicating a biological gradient consistent with glycemic deterioration.

In the subcohort with normal fasting glucose and HbA1c, 2-HB showed robust discriminatory ability for postprandial dysglycemia with an AUC of 0.79, signifying good accuracy. A threshold of 39 µmol/L achieved 90% sensitivity, minimizing false negatives, and a remarkably high negative predictive value of 98.9%, suggesting strong capacity to rule out dysglycemia.

Multivariate logistic regression revealed that each one standard deviation increase in 2-HB was associated with a 2.23-fold higher odds of dysglycemia (P < 0.001), independent of fasting glucose and HbA1c. This supports 2-HB as an independent biomarker linked to early glycemic abnormalities often undetected by routine fasting measures.

Safety or adverse effects were not applicable given the assay’s biochemical nature; however, its rapid enzymatic design promises scalability and clinical feasibility.

Expert Commentary

The results highlight the clinical utility of enzymatic 2-HB measurement as a screening biomarker that fills an important diagnostic gap. While fasting glucose and HbA1c are standard, their limitations in capturing postprandial glucose excursions and early dysglycemia are well documented. Introducing a simple enzymatic assay for 2-HB could dramatically enhance screening, enabling earlier detection and intervention before overt diabetes develops.

Mechanistically, 2-HB generation is linked to increased oxidative stress and perturbations in glutathione metabolism triggered by insulin resistance and impaired glucose regulation. This biological plausibility reinforces its value as a metabolic sentinel biomarker.

Yet, some considerations remain. The single-cohort design calls for verification across more diverse populations and longitudinal studies evaluating predictive value for progression to diabetes. Moreover, while the enzymatic assay offers rapid turnaround and potential cost-effectiveness, widespread clinical adoption will require validation in real-world diagnostic workflows and harmonization with standard testing protocols.

In the context of existing guidelines, screening via fasting glucose and HbA1c remains predominant. Integration of 2-HB testing could complement but not replace these established markers currently. Further evidence from intervention studies demonstrating improved clinical outcomes based on 2-HB-guided screening would strengthen its positioning.

Conclusion

The enzymatic measurement of fasting 2-hydroxybutyrate represents a promising advancement in dysglycemia screening, providing incremental diagnostic value beyond conventional fasting plasma glucose and HbA1c measures. Its high sensitivity and negative predictive value for postprandial dysglycemia in individuals with ostensibly normal fasting profiles suggest it could become a powerful tool to identify patients at risk earlier and more accurately. Pending further validation, enzymatic 2-HB assay could support earlier lifestyle or therapeutic interventions, potentially mitigating progression to type 2 diabetes and its complications.

Funding and ClinicalTrials.gov

The study was supported by institutional grants associated with the Biomarkers of Personalized Medicine cohort. No clinical trial registration number was reported for this observational biomarker validation study.

References

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