Effect of blood sampling schedule on the ability to discriminate between postprandial glycemic responses

The blood glucose responses elicited by foods are often determined using blood samples taken at 15-min intervals. Our objective was to see whether taking blood samples at 10-min intervals affected the results.

Overnight-fasted healthy subjects (n=11) were studied on nine different occasions with seven different test meals. Blood samples were obtained at fasting and at 10, 15, 20, 30, 40, 45, 50, 60, 90, and 120 min after starting to eat. Peak rise, incremental area under the curve, and relative glycemic response were calculated using the 10- and 15-min sampling schedules.

With 10-min intervals, peak rise was 4% greater than with 15-min intervals (P<0.001), but sampling interval did not significantly affect mean incremental area under the curve or relative glycemic response. The 10-min blood sampling schedule had a slightly greater ability to discriminate between foods and between subjects for peak rise and relative glycemic response.

We conclude that the blood sampling schedule used may influence the accuracy and precision of measurements of glycemic response; however, the difference between taking blood samples at 10-min and 15-min intervals is quite small.