Daily Glucose Profiles in Japanese People with Normal Glucose Tolerance as Assessed by Continuous Glucose Monitoring

Background: Little information is available regarding glucose fluctuations in postprandial states and during the oral glucose tolerance test (OGTT) in Japanese people with normal glucose tolerance (NGT). Methods: Glucose profiles of 27 Japanese people were measured for 4 days by using continuous glucose monitoring. A 75-g OGTT was conducted on the second day, and 24 subjects diagnosed with NGT by a 75-g OGTT were enrolled. The subjects were monitored for their postprandial glucose profile in their ordinary daily life on the third day. Results: The results of our study have shown that the median time (interquartile range) to maximum glucose levels in OGTT was 38 (25-49) min after glucose load and that the median time to maximum glucose levels after breakfast, lunch, and dinner was 40 (31-75), 50 (30-70), and 45 (36-50) min, respectively. The median increase in glucose during OGTT was 45 (35-66) mg/dL, and that after breakfast, lunch and dinner was 21 (12-32), 37 (27-48), and 44 (25-63) mg/dL, respectively. Those with a higher insulinogenic index reached their maximum glucose levels in a shorter time (r = -0.46, P = 0.025) and had smaller glucose increments during OGTT (r = 0.49, P = 0.014). Conclusions: This study is the first report to document the glucose profile of Asian people with NGT.