Effects of cooked rice containing high resistant starch on postprandial plasma glucose, insulin, and incretin in patients with type 2 diabetes.

Background and objectives: Few studies exist on resistant starch in rice grains. The Okinawa Institute of Science and Technology Graduate University (OIST) has developed a new rice (OIST rice, OR) rich in resistant starch. This study aimed to clarify the effect of OR on postprandial glucose concentrations.

Methods and study design: This single-center, open, randomized, crossover comparative study included 17 patients with type 2 diabetes. All participants completed two meal tolerance tests using OR and white rice (WR).

Results: The median age of the participants was 70.0 [59.0-73.0] years, and the mean body mass index was 25.9±3.1 kg/m2. The difference in total area under the curve (AUC) of plasma glucose was -8223 (95% confidence interval [CI]: -10100 to -6346, p<0.001) mg·min/dL. The postprandial plasma glucose was significantly lower with OR than with WR. The difference in the AUC of insulin was -1139 (95% CI: -1839 to -438, p=0.004) µU·min/mL. The difference in the AUC of total gastric inhibitory peptide (GIP) and total glucagon-like peptide-1 (GLP-1) was -4886 (95% CI: -8456 to -1317, p=0.011) and -171 (95% CI: -1034 to 691, p=0.673) pmol·min/L, respectively.

Conclusions: OR can be ingested as rice grains and significantly reduced postprandial plasma glucose compared to WR independent of insulin secretion in patients with type 2 diabetes. OR could have escaped absorption not only from the upper small intestine but also from the lower small intestine.