Parboiled Rice and Glycemic Control: Effects on Postprandial Glucose, Insulin Sensitivity, and Incretin Response in Healthy and Type 2 Diabetic Individuals, a Pilot Study

Type 2 diabetes Mellitus (T2DM) is a growing global health concern, particularly in regions where rice is a dietary staple. Parboiled rice (PBR) has been proposed as a lower glycemic index alternative to white rice (WR), potentially improving postprandial glucose control. However, the effects of PBR on insulin sensitivity, β-cell function, and incretin hormone response remain unclear. This pilot study aimed to evaluate the effects of PBR compared to WR on postprandial glucose, insulin sensitivity, and incretin hormone responses in both healthy individuals and those with T2DM. Twenty subjects (n = 10 / group) participated in a randomized, crossover study. Blood samples were collected at fasting and postprandial time points after rice consumption to measure glucose, insulin, and GLP-1 levels. Insulin resistance / sensitivity and β-cell function were assessed using HOMA-IR, Matsuda Index (MI), and Disposition Index (DI). Fasting glucose and insulin levels were significantly higher in T2DM subjects compared to healthy individuals. PBR resulted in significantly lower glucose levels in healthy participants compared to WR. In T2DM subjects, PBR substantially reduced glucose levels but did not reach statistical significance. Insulin responses followed a similar pattern. GLP-1 responses were lower in T2DM subjects. MI and DI were significantly higher after PBR in healthy individuals compared to T2DM subjects suggesting improved insulin sensitivity. PBR demonstrated potential benefits in lowering postprandial glucose levels and improving insulin sensitivity. Further research with a larger sample size is needed to confirm these findings and explore the mechanisms underlying PBR’s effects in T2DM management. This study was supported by the Kuwait University research grant, Project # YF03/18.