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. Supplementary Information: The online version contains supplementary material available at 10.1007/s13340-021-00552-z. © The Japan Diabetes Society 2021.