New York, Dec 13 (IANS): Ever wondered why orally-administered drugs for diabetes work for some people but not for others? According to researchers, including one of Indian origin, bacteria that make up the gut microbiome might be the reason.

The study, from the Wake Forest University in the US, examined how gut bacteria either enhanced or inhibited a drug's effectiveness.

"Certain drugs work fine when given intravenously and go directly to the circulation, but when they are taken orally and pass through the gut, they do not work," said Hariom Yadav, Assistant Professor from the varsity.

"Conversely, metformin, a commonly used anti-diabetes drug, works best when given orally but does not work when given through an IV," he added.

Examining interactions between the most commonly prescribed anti-diabetic drugs with the microbiome, the team found that before being absorbed into the bloodstream, many orally-administered drugs are processed by intestinal microbial enzymes.

As a result, the gut microbiome influences the metabolism of the drugs, thereby affecting patients' responses, Yadav said, in the paper published in the journal EBioMedicine.

"Our review showed that the metabolic capacity of a patient's microbiome could influence the absorption and function of these drugs by making them pharmacologically active, inactive or even toxic," Yadav said.

"We believe that differences in an individual's microbiome help explain why drugs will show a 90 or 50 per cent optimum efficacy, but never 100 per cent," he noted.

Importantly, modulation of the gut microbiome by drugs may represent a target to improve, modify or reverse the effectiveness of current medications for Type-2 diabetes, the researchers noted.