607-P: Associations of Gut Microbiome with Glycemic Control in a Carbohydrate-Restricted, High-Protein Diet for Type 2 Diabetes Mellitus

Objective: The Low Biologically Available Glucose (LoBAG) diet was designed to improve glycemic control of type 2 diabetes mellitus (T2D). We evaluate changes in the gut microbiome when participants with T2D are given the LoBAG diet.

Methods: Thirty-six participants with T2D taking metformin or no glucose-lowering medication were enrolled in a 12-week randomized controlled trial. Participants were randomly assigned to the LoBAG diet (30% low-starch carbohydrate, 30% protein, 40% fat) or a control diet (50% carbohydrate, 15% protein, 35% fat). Fecal samples were collected at weeks 0, 6, and 12 along with the primary outcome, hemoglobin A1c (HbA1c).

Results: Diet groups were significantly distinct in terms of Bray-Curtis dissimilarity in weeks 6 and 12 following the dietary intervention (p<0.001, PERMANOVA), indicating shifts in the microbiome profile following the diet intervention. In particular, abundance of Firmicutes was lower in the LoBAG diet group (Mann-Whitney U test, p < 0.001). The primary outcome, HbA1c, was significantly more reduced in the LoBAG diet group (t-test, p=0.04, week 12 - baseline) following dietary intervention.

Conclusions: Participants with T2D consuming the LoBAG diet had greater reduction in HbA1c over 12 weeks than those consuming a control diet. This difference was also associated with shifts in the gut microbiome, but further studies are needed to explore a relationship between HbA1c and the gut microbiome.