Dietary treatment with rice containing resistant starch improves markers of endothelial function with reduction of postprandial blood glucose and oxidative stress in patients with prediabetes or newly diagnosed type 2 diabetes

Objective: We aimed to evaluate whether 4-week of dietary treatment with rice containing resistant starch reduces blood glucose and oxidative stress as well as improves endothelial function. Methods: Patients with impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or newly diagnosed type 2 diabetes (n = 90) were randomly assigned to either a group ingesting rice containing 6.51 g resistant starch daily or a control rice group for 4-weeks. We assessed fasting and postprandial levels of glucose and insulin, oxidative stress markers and endothelial function using reactive hyperemia peripheral arterial tonometry (RH-PAT). Results: The diet containing rice with resistant starch reduced fasting insulin and insulin resistance, postprandial glucose (P = 0.010) and insulin levels at 30 min, and glucose and insulin areas under the response curve after the standard meal. Rice with resistant starch also decreased urinary 8-epi-PGF_2α and plasma malondialdehyde (MDA) and increased the RH-PAT index (P < 0.001) and total nitric oxide (NO). Postprandial changes in glucose at 60 and 120 min and areas under the glucose response curve, MDA, RH-PAT, and total NO of the test group differed significantly from those in the control even after adjusting for baseline values. Overall, changes in the RH-PAT index correlated positively with changes in total NO (r = 0.336, P = 0.003) and superoxide dismutase activity (r = 0.381, P = 0.001) and negatively with changes in MDA (r = -0.358, P = 0.002) and 8-epi-PGF_2α. Conclusions: In patients with IFG, IGT or newly diagnosed type 2 diabetes, 4-weeks of dietary treatment with rice containing resistant starch was associated with improved endothelial function with reduction of postprandial glucose and oxidative stress compared with control.