Effects of the soluble fiber complex PolyGlycopleX® (PGX®) on glycemic control, insulin secretion, and GLP-1 levels in Zucker diabetic rats

The effects of the novel water soluble, viscous fiber complex PolyGlycopleX® [(α- d-glucurono-α- d-manno-β- d-manno-β- d-gluco), (α- l-gulurono-β- d mannurono), β- d-gluco-β- d-mannan (PGX®)] on body weight, food consumption, glucose, insulin, and glucagon-like peptide (GLP-1) levels were determined in Zucker diabetic rats (ZDFs). Such fibers are thought to improve glycemic control through increased GLP-1 induced insulin secretion. ZDFs were treated 12 weeks with normal rodent chow supplemented with cellulose (control, inert fiber), inulin or PGX® at 5% wt/wt and effects on body weight, glycemic control, and GLP-1 determined. In the fed state, PGX® reduced blood glucose compared to the other groups from week 5 until study termination while insulin was significantly elevated when measured at week 9, suggesting an insulin secretagogue effect. Fasting blood glucose was similar among groups until 7–8 weeks when levels began to climb with a modest reduction caused by PGX®. An oral glucose tolerance test in fasted animals (week 11) showed no change in insulin sensitivity scores among diets, suggesting an insulinotropic effect for PGX® rather than increased insulin sensitivity. PGX® increased plasma levels of GLP-1, while HbA 1c was markedly reduced by PGX®. Body weights were not changed despite a significant reduction in food consumption induced by PGX® up to week 8 when the PGX®-treated group showed an increase in body weight despite a continued reduction in food consumption. PGX® improved glycemic control and reduced protein glycation, most likely due to the insulin secretagogue effects of increased GLP-1.