Metabolism

Glucose tolerance tests: curves and area under the curve

How to run, analyse and report a glucose tolerance test in mice and other models.

The test

After a fast (commonly 4–6 hours; longer fasts change the result), measure baseline blood glucose, give glucose (often 1–2 g/kg body weight, intraperitoneally or by gavage) and measure again at set times, typically 15, 30, 60, 90 and 120 minutes. Keep fasting length, dose route and timing the same across groups, and record them for the methods.

Two ways to analyse

• The curve: compare groups across time with a two-way repeated-measures ANOVA (group × time) or a mixed model, followed by multiple comparisons at each time point if the interaction is significant.
• Area under the curve (AUC): summarise each animal’s curve as one number with the trapezoidal rule, then compare groups with a t-test or one-way ANOVA.

Total or incremental AUC?

Total AUC includes the baseline glucose. Incremental AUC (iAUC) subtracts each animal’s baseline and reflects the response to the glucose load itself. If groups differ at baseline, report both and say which one your conclusion rests on.

Insulin tolerance test

The same design with insulin instead of glucose; results are often shown as % of baseline glucose, and the area above the curve or the initial rate of fall is compared.

Report

Fast length, glucose dose and route, time points, the glucometer or assay, and how AUC was calculated.

Published 2026 by Dr. Ambuj Shahi. This guide is general information for researchers; follow your institution’s and journal’s requirements.