Metformin has been one of the most popular drugs used to treat type 2 diabetes for more 60 years, but researchers continue to debate whether it is primarily working through the bloodstream or through the bowel. A new study suggests it works in part by altering proportions of bacteria (particularly Akkermansia and Bifidobacterium) in the gut, which appear to influence blood-sugar levels.

Why it matters: The study, combined with earlier research, suggests certain bacteria in the intestines may play a role in controlling type 2 diabetes. Scientists are always looking for a better way to control sugar levels in the roughly 27 million Americans with type 2 diabetes, which the World Health Organization has predicted will be the seventh leading cause of death by 2030. Fredrik Backhed at the University of Gothenburg, Sweden — a co-author of the new study told New Scientist that he hopes some people might be able to change their gut bacteria via their diet in order to get benefits similar to those from taking Metformin.