An examination was conducted to verify D-psicose suppressed the elevation of blood glucose and insulin concentration in a dose-dependent manner under the concurrent administration of maltodextrin and D-psicose to healthy humans. Twenty subjects aged 20-39 y, 11 males and 9 females were recruited. A load test of oral maltodextrin was conducted as a randomized single blind study. The subjects took one of five test beverages (7.5 g D-psicose alone, 75 g maltodextrin alone, 75 g maltodextrin +2.5, 5 or 7.5 g D-psicose). Blood was collected before an intake and at 30, 60, 90 and 120 min after an intake. Intervals of administration were at least 1 wk. The load test with 75 g maltodextrin showed significant suppressions of the elevation of blood glucose and insulin concentration under the doses of 5 g or more D-psicose with dose dependency. An independent administration of 7.5 g D-psicose had no influence on blood glucose or insulin concentration. D-Psicose is considered efficacious in the suppression of the elevation of blood glucose concentration after eating in humans.

Background: d-Allulose is a rare sugar with antiobesity and antidiabetic activities. However, its direct effect on insulin sensitivity and the underlying mechanism involved are unknown. Objective: This study aimed to investigate the effect of d-allulose on high-fat diet (HFD)-induced insulin resistance using the hyperinsulinemic–euglycemic (HE)-clamp method and intramuscular signaling analysis. Methods: Wistar rats were randomly divided into three dietary groups: chow diet, HFD with 5% cellulose (HFC), and HFD with 5% d-allulose (HFA). After four weeks of feeding, the insulin tolerance test (ITT), intraperitoneal glucose tolerance test (IPGTT), and HE-clamp study were performed. The levels of plasma leptin, adiponectin, and tumor necrosis factor (TNF)-α were measured using the enzyme-linked immunosorbent assay. We analyzed the levels of cell signaling pathway components in the skeletal muscle using Western blotting. Results: d-allulose alleviated the increase in HFD-induced body weight and visceral fat and reduced the area under the curve as per ITT and IPGTT. d-Allulose increased the glucose infusion rate in the two-step HE-clamp test. Consistently, the insulin-induced phosphorylation of serine 307 in the insulin receptor substrate-1 and Akt and expression of glucose transporter 4 (Glut-4) in the muscle were higher in the HFA group than HFC group. Furthermore, d-allulose decreased plasma TNF-α concentration and insulin-induced phosphorylation of stress-activated protein kinase/Jun N-terminal kinase in the muscle and inhibited adiponectin secretion in HFD-fed rats. Conclusions: d-allulose improved HFD-induced insulin resistance in Wistar rats. The reduction of the proinflammatory cytokine production, amelioration of adiponectin secretion, and increase in insulin signaling and Glut-4 expression in the muscle contributed to this effect.

D-Allulose altered hepatic metabolites, especially those related to the lipid metabolism processes, such as the fatty acid β-oxidation, cholesterol, bile acid, and glucuronic acid/xylulose pathways.