Spotlight on the gut microbiome
A Finnish study found that certain gut bacteria were more common in people who later developed type 2 diabetes, while an Israeli study identified a distinct microbial signature in adults with type 1 diabetes compared with healthy controls.
Two recent studies looked at the associations between bacteria in the gut and type 1 and type 2 diabetes, finding certain species to be more common in patients with the diseases.
The first study, conducted in Finland and published by Diabetes Care on Jan. 31, used fecal samples from 5,572 patients without diabetes at baseline. Over median follow-up of 15.8 years, 432 cases of type 2 diabetes were diagnosed. Four species were consistently associated with incident diabetes: Clostridium citroniae (hazard ratio [HR], 1.21; 95% CI, 1.04 to 1.42), C. bolteae (HR, 1.20; 95% CI, 1.04 to 1.39), Tyzzerella nexilis (HR, 1.17; 95% CI, 1.01 to 1.36), and Ruminococcus gnavus (HR, 1.17; 95% CI, 1.01 to 1.36). Two species clusters were significantly associated with diabetes and mostly consisted of these same species. “These findings build on and extend previous mainly cross-sectional evidence and further support links between dietary habits, metabolic diseases, and type 2 diabetes that are modulated by the gut microbiome,” the authors said. “All four observed diabetes-associated taxa have been previously linked with other metabolic diseases and risk factors.” They noted that additional research in this area could improve prediction of diabetes as well as lead to treatments for type 2 diabetes that modify the gut microbiome. The generalizability of the results to other countries is uncertain, and they should be validated in other cohorts, the authors noted.
The other study, conducted in Israel and published by Diabetes Care on Jan. 20, compared fecal samples of 74 adults with type 1 diabetes and 296 age-matched healthy controls. The diabetes patients had a distinct microbial signature that separated them from control subjects; there were several bacterial species with significantly higher scores in type 1 diabetes, including Prevotella copri and Eubacterium siraeum, and several with higher scores in control subjects, including Firmicutes bacterium and Faecalibacterium prausnitzii (P<0.05). The study also looked at data from continuous glucose monitoring and blood tests and found several bacterial taxa and metabolic pathways to be associated with glycemic control. The study was limited by its observational nature, and additional research will be needed to determine whether the identified bacteria are a cause or an effect of diabetes. “Our findings provide a foundation for additional large-scale analyses of the gut microbiome” in type 1 diabetes patients, which could eventually lead to development of novel therapeutic strategies, the authors said.