Association of the gut microbiome and metabolome with the dynamics of laboratory parameters in individuals with type 2 diabetes and obesity after bariatric surgery

Background. It is known that the gut microbial community has a significant impact on the health of the host organism. It has been shown that changes in the composition and metabolic potential of the microbiota occur in people with obesity and diabetes type 2 (T2D). However, the impact of the microbiota on metabolic changes after bariatric surgery remains unclear.

Aim. To assess the influence of the gut microbiome composition on metabolic parameters in patients with obesity and T2D after bariatric surgery.

Materials and methods. The study included patients with T2D and obesity, who were treated with bariatric surgery (gastric bypass). Before surgery, as well as 6 and 12 months after surgery, the anthropometric, laboratory parameters were measured, feces were collected for analysis of the intestinal microbiota. The microbiota composition was determined through sequencing of the 16S rRNA gene from stool samples. For a subset of patients, the stool metabolome was also studied.

Results. After surgery, there was a significant positive trend in weight loss, glycemia, lipid spectrum parameters, and insulin resistance. However, patients did not achieve target levels of 25(OH) vitamin D and calcium. Taxa were identified whose abundance before surgery was associated with the dynamics of parathyroid hormone and vitamin D. The order Verrucomicrobiales was negatively associated with vitamin D dynamics, while the order Fusobacteriales, which includes hydrogen sulfide producers in the gut, was positively associated with the increase in parathyroid hormone. Interestingly, these bacteria were also elevated in patients with higher total cholesterol levels prior to intervention, whereas other H₂S producers in the gut correlated with C-peptide levels. No significant associations between the metabolome and clinical parameters' were found; however, the correlation structure of microbiome and metabolome data in patients with obesity was examined.

Conclusion. The study revealed an association between several intestinal microbiota species and metabolic parameters after bariatric interventions. These results are pilot and, if reproduced, may allow the prediction of the bariatric surgery effects on weight and glycemia based on the composition of the gut microbiota.