The effect of white rice (WR) mixed with high β-glucan-containing barley at 50% on improvement of postprandial blood glucose levels was assessed by meal tolerance test and continuous glucose monitoring (CGM) in 15 healthy subjects with normal glucose tolerance (age 31.6 ± 12.9 years old, 4 males and 11 females). A meal tolerance test (500 kcal) was conducted using 2 types of test meals: a test meal only with WR and a test meal WR mixed 50% barley, and the side dish was the same in both meals. Blood glucose levels of the subjects 180 minutes after ingestion of the test meals were compared. In addition, a CGM device was attached to the subjects for 2 days when the WR or barley as a staple food was provided 3 times a day for consecutive days, and the daily variation of glucose was investigated. The glucose levels 30 minutes after dietary loads and the area under the blood concentration-time curve over 180 minutes were significantly decreased in the barley consumption group. In CGM, 24-hour mean blood glucose and 24-hour standard deviation of blood glucose were also significantly decreased after ingestion of the barley. Postprandial glucose level elevation was suppressed by mixing high-β-glucan barley with WR in subjects with normal glucose tolerance.

The aim of our study was to investigate whether high β-glucan-containing barley (7.2 g per 100 g) improves postprandial plasma glucose levels and suppresses postprandial insulin levels during a meal tolerance test in type 2 diabetic patients. A meal tolerance test (500 kcal) was conducted using two types of test meals: a test meal with white rice (WR) alone (WR diet) and a test meal with WR mixed with 50% barley (BR diet) as staple food. The side dish was the same in the both meals. The changes in plasma glucose and serum C-peptide immunoreactivity (CPR) levels for 180 minutes after ingestion of the test meals were compared. Ten patients with type 2 diabetes (age 52.5 ± 15.1 years, and 7 males and 3 females) were included in this study. The mean HbA1c level and body mass index were 8.8 ± 1.4%, and 29.7 ± 4.5 kg/m 2 , respectively. Plasma glucose levels after ingestion of the WR diet or BR diet peaked at 60 minutes, which showed no significant differences between the two types of test meals. However, the incremental area under the curve (IAUC) of plasma glucose levels after ingestion of BR diet was significantly lower than that of WR diet. The serum CPR levels at 180 min and their IAUC over 180 minutes after ingestion of BR diet were significantly lower than those of WR diet. Conclusion: Increase in postprandial plasma glucose and insulin levels was suppressed by mixing high-β-glucan barley with WR in type 2 diabetic patients.

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