Effects of barley intake on glycemic control in Japanese patients with type 2 diabetes mellitus undergoing antidiabetic therapy: a prospective study

Background Barley reportedly reduces postprandial hyperglycemia in healthy individuals. However, its effects in patients with type 2 diabetes mellitus (T2DM) undergoing antidiabetic therapy remains unclear. This study aimed to clarify the effects of barley intake on postprandial hyperglycemia in T2DM patients who use metformin or acarbose. Methods T2DM patients who were undergoing dietary therapy without medications (naive), with metformin, or with acarbose ( n = 10/group) were recruited. They were instructed to eat white rice twice per day for 5 days, followed by barley-mixed rice twice per day for 6 or 7 days. Subsequently, blood glucose fluctuations in the interstitial fluid glucose were measured using a continuous glucose monitoring device. Meal tolerance tests were performed using test diets containing white rice and barley-mixed rice before and after the trial, respectively. Results Postprandial hyperglycemia was lower in patients taking barley-mixed rice than in those taking white rice in each group. However, the AUC of blood glucose concentration in the acarbose-treated patients showed only a trend. Mean amplitude of glycemic excursions (MAGEs) decreased in patients who consumed barley-mixed rice. Additionally, although MAGEs in the naive decreased, it did not in the metformin- ( P = 0.098) and acarbose-treated ( P = 0.29) patients. Conclusion Barley-mixed rice lowers postprandial glucose concentrations in treatment-naive and metformin-treated T2DM patients, and shows a trend in acarbose-treated patients. Therefore, using barley-containing diets as dietary therapy may be useful in improving glycemic control in diabetes patients. Trial registration UMIN000028623.