Imbalance in gut bacteria may up risk of diabetes

Last Updated: 2016-07-21

By Megan Brooks

NEW YORK (Reuters Health) - Excess weight and physical inactivity aren't the only contributors to insulin resistance. A new study shows that imbalances in certain bacteria in the gut can contribute to insulin resistance.

"We show that specific imbalances in the gut microbiota are essential contributors to insulin resistance, a forerunner state of widespread disorders like type 2 diabetes, hypertension and atherosclerotic cardiovascular diseases, which are in epidemic growth," senior investigator Dr. Oluf Pedersen, of the Metabolism Center at the University of Copenhagen, said in a news release.

The Danish study included 277 non-diabetic adults and 75 with type 2 diabetes. "By integrating data on host insulin sensitivity and metabolic syndrome, gut microbiome, and fasting serum metabolome, we were able to demonstrate clear metabolome signatures of IR (insulin resistance) phenotypes among non-diabetic individuals and validate them in patients with type 2 diabetes," the authors wrote in the journal Nature July 13.

"In those non-diabetic individuals who are insulin resistant and therefore at increased risk of developing type 2 diabetes, we observe links between the relative abundance of two different bacteria (Prevotella copri and Bacteroides vulgatus) and branched chain amino acids (BCAA) in the serum metabolome - and insulin resistance at the whole body level of the host," Dr. Pedersen added in email to Reuters Health.

"These findings are replicated in type 2 diabetic patients. Also feeding mice one of these bacteria (Prevotella copri) together with high fat diet aggravates glucose intolerance, and insulin resistance in parallel with an increase in circulating BCAA," he said.

For now, Dr. Pedersen cautioned, "Our study represents basic research and has no direct clinical implications."

He said prospective studies where people with prediabetes are examined for their level of insulin sensitivity, insulin secretory capacity and their gut microbiome at baseline and followed for years are needed to confirm or refute the findings in this cross-sectional study.

"If specific imbalances of gut microbiota composition and function at baseline do predict progression from prediabetes to overt type 2 diabetes, such pieces of evidence might suggest potential causality. Obviously, prospective clinical studies should also be complemented with mechanistic studies in animals and in cell models to elucidate the molecular events involved in the disease pathogenesis," Dr. Pedersen said.

The study had no commercial funding and the authors have no relevant disclosures.

SOURCE: http://go.nature.com/2auFLFz

Nature 2016.