Oral glucose tolerance test (OGTT) is used as a standard to diagnose people with diabetes. However, it does not reflect the total glucose load. The aim of this study was to explore correlation between blood glucose values at different times during OGTT and the Incremental Area under the Curve (IAUC), to investigate whether there might be a time point for glucose measurement which would best represent the total glucose load. OGTT were performed in 196 Norwegian-Pakistani women, and glucose was measured fasting and every 15 minute up to 2 hours. The results indicate that fasting values are least correlated with total glucose load, but that values measured at 75, 90 and 60 minutes represent it the best. We suggest that fasting values fail to mirror total glucose load in many cases, and that 2 hour values may be inferior to earlier ones in representing glucose load. High-risk groups, such as Pakistani immigrants, may especially take advantage from improvements in methods to diagnose diabetes.