Effect of a functional fibre supplement on glycemic control when added to a year-long medically supervised weight management program in adults with type 2 diabetes

Soluble fibre beneficially affects metabolism but whether it can augment the reductions in glycemia induced through intensive weight management has not been extensively studied. Our objective was to examine the adjunct effect of the soluble viscous fibre PGX® on glycemic control in adults with type 2 diabetes (T2D) enrolled in a year-long medically supervised weight management program. In a placebo-controlled, double-blind study, 290 adults with overweight/obesity and T2D were randomized to receive PGX (15–20 g/day) or isocaloric placebo (rice flour, 6.4–8.6 g/day) as an adjunct to intensive weight management for 52 weeks. The primary outcome was change in glycemic control (HbA1c). Other outcome measures included weight loss, blood lipids, blood pressure, cytokines and fecal microbiota. Compared to baseline HbA1c in PGX (7.2 ± 1.1%) and placebo (7.0 ± 0.9%) groups, there was a significant reduction at 16 and 26 weeks, however, only PGX showed a significant absolute reduction of 0.23% at 52 weeks; there were no between-group differences in HbA1c. At 52 weeks, only PGX significantly decreased body weight compared to baseline and reduced waist circumference at all time points. Compared to baseline, only PGX showed a significant reduction in LDL cholesterol at 16 and 26 weeks. PGX significantly increased the relative abundance of Collinsella, Parabacteroides and Roseburia. Adding PGX to a weight management program for individuals with T2D provides a sustained reduction in HbA1c compared to placebo. Improvements in other metabolic outcomes suggest that PGX may be a promising adjunct to weight loss programs in patients with T2D. This trial was registered at ClinicalTrials.gov as NCT01644201.