Glucose Tolerance Testing and Diabetes Risk Assessment

Oral glucose tolerance testing (OGTT) remains the gold standard for assessing post-prandial glucose handling and stratifying individuals according to diabetes risk. Following a period of overnight fasting, participants ingest a standardised 75 g glucose load, with plasma glucose and often insulin measured at fasting and at intervals up to two hours. Thresholds for impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and overt diabetes are defined by fasting and two-hour glucose concentrations, yet growing evidence highlights the utility of intermediate time points, notably the one-hour post-load value, and the shape of the glucose excursion curve. These dynamic indices capture early-phase insulin secretion, β-cell reserve and insulin sensitivity more sensitively than static measures. Integration of advanced glycaemic biomarkers, risk scores and machine-learning models has further refined individual risk prediction, facilitating personalised prevention strategies and early therapeutic intervention on a global scale.

Research from Nature Portfolio

Recent studies have extended the capabilities of OGTT by incorporating continuous glucose monitoring to map sub-minute glycaemic responses, revealing heterogeneity in early insulin secretory patterns that predict future dysglycaemia. Multi-omics analyses of blood samples collected during OGTT have identified novel glycoprotein acetylation markers and lipid-derived metabolites that enhance prediction of microvascular complications beyond conventional glucose measurements. Advanced statistical and machine-learning techniques applied to full glucose and insulin time-course data have achieved improved discrimination of individuals at high risk of progression to type 2 diabetes, supporting the development of dynamic risk calculators suitable for diverse populations.

Glucose Tolerance Testing and Diabetes Risk Assessment publication trend

The graph below shows the total number of articles in glucose tolerance testing and diabetes risk assessment across all publications each year (not limited to Nature Index journals).

Technical terms

Oral glucose tolerance test (OGTT): A diagnostic procedure measuring plasma glucose (and often insulin) at set intervals after ingestion of a 75 g glucose solution to assess glucose regulation.

Impaired fasting glucose (IFG): Elevated fasting plasma glucose below the diabetic threshold, indicating increased diabetes risk.

Impaired glucose tolerance (IGT): Two-hour post-load plasma glucose above normal but below diabetic levels, reflecting post-prandial dysglycaemia.

One-hour post-load glucose: Plasma glucose measured at 60 minutes during OGTT, emerging as a sensitive early predictor of dysglycaemia and cardiovascular risk.

β-cell function: The capacity of pancreatic β cells to secrete insulin in response to glucose stimulation, often estimated by indices derived from OGTT.

Insulin resistance: A diminished physiological response to circulating insulin, typically assessed by surrogate indices such as HOMA-IR or dynamic measures from OGTT.

Area under the curve (AUC): The integral of glucose (or insulin) concentration over time during OGTT, summarising total exposure.

References

1. Characteristics and Risk of Diabetes in People With Rare Glucose Response Curve During an Oral Glucose Tolerance Test. The Journal of Clinical Endocrinology & Metabolism (2023).
2. Prediabetes and Cardiometabolic Risk: The Need for Improved Diagnostic Strategies and Treatment to Prevent Diabetes and Cardiovascular Disease. Biomedicines (2024).
3. One-hour glucose is an earlier marker of dysglycemia than two-hour glucose. Diabetes Research and Clinical Practice (2023).