Predicting more accurately the overall glucose response to a lunch meal by using the postprandial glucose peak

Although the assessment of postprandial glycemia is clinically important, the most relevant time points with the smallest number of blood samples giving the highest predictive power have yet to be established. It has been suggested that a sample estimating the postprandial peak concentration would improve this predictive power compared to the usual recommended time points. In this study, we assessed the power of these time points to predict the glucose response to a meal mimicking everyday life. Subjects were 11 healthy young men (mean age, 22 +/- 1 years; body mass index, 21.7 +/- 1.8 kg/m(2)). Plasma glucose, insulin, and nonesterified fatty acids were measured by continuous collection of blood in tubes filled every 5 minutes for 240 minutes after a 2-item lunch meal consumed ad libitum on the first test day, and in the same amount 1 week later. The most relevant time point for the plasma glucose peak level was found at 45 minutes (mean interval, 47 +/- 3 minutes) and was not dependent on the energy intake at lunch. Its coefficient of variation was low (7.0% +/- 1.5%). The best predictive equation for the whole postmeal glucose area under the curve (AUC) was found at 120 minutes and involved glucose, insulin, and nonesterified fatty acids (r(2) = 0.89; P < 10(-7)). The 120-minute postmeal glucose profile constructed with the 0-, 45-, 90-, and 120-minute time points overlapped more accurately with the actual profile than did the time points normally used in the glucose tolerance test, and slightly improved the correlation between the calculated and the actual plasma glucose area under the curve (r = 0.96; P < 10(-7)). In conclusion, in healthy, young, lean male subjects, a blood sample collected 45 minutes after a spontaneous lunch meal estimates the postprandial plasma glucose peak and suggests that including the peak level along with 90- and 120-minute time points may improve the predictive power of the plasma glucose profile after a meal.