Intestinal bacteria are affected by diabetes medicine

Most of the approximately 100 trillion bacteria that live hidden in the human gut are difficult to grow in the traditional way, because they do not tolerate atmospheric oxygen. Within the past few years, new research driven by deep analysis of bacterial DNA and advanced bioinformatics has made it possible to analyze the composition and function of the hundreds of different bacterial species in the human intestines. The bacteria produce thousands of substances that affect our physiology and health in countless ways.

In disease research, changes in intestinal bacteria composition and function - called dysbiosis - come into focus. During previous studies, the researchers did not take into account the possible effects that drugs can have on the bacteria in the patients' intestines. Therefore, it was difficult to determine which dysbiosis associated with particular diseases and which changes of intestinal bacteria are associated with medical treatment. At the same time, conflicting results were reported from intestinal bacterial research of the same disease. The reason for that could be that the studies did not take into consideration an effect of medication on the gut microbial ecology.

Metformin triggers the intestinal bacterial communities to produce fatty acids
European and Chinese researchers in the EU-funded MetaHIT consortium have carried out studies of intestinal bacteria from Danish, Swedish, and Chinese patients with type 2 diabetes and similar healthy people – in total, studies of 784 people. Here, the aim was to separate the changes in the intestinal bacteria that are associated with disease from changes that may be associated with intake of certain drugs. The results have just been published in the prestigious international journal Nature.

The study shows that the most widely used drug for the treatment of high blood sugar, metformin, changes the intestinal bacteria in type 2 diabetes patients in favorable directions. This means that there is a larger capacity among the bacteria to produce certain types of short-chain fatty acids such as butyric acid and propionic acid. These fatty acids may in different ways lower blood sugar levels. The drug metformin has been also known to have adverse effects on the gastrointestinal tract for example bloating and increased flatulence. The researchers have found a possible explanation to it, since metformin-treated patients have more Coli bacteria that may cause the intestinal discomfort.

"We could not show that other types of diabetes medications had any substantial impact on the intestinal bacteria. In contrast, we demonstrated that in studies of type 2 diabetes patients who were not treated with metformin, that they all, whether they were from Denmark, China or Sweden, had fewer of the bacteria producing the health promoting short-chain fatty acids. Whether the lack of certain combinations of fatty acid-producing intestinal bacterial species in untreated patients are a contributing causative factor to type 2 diabetes disease is currently under investigation, "says Professor Oluf Borbye Pedersen from the Novo Nordisk Foundation Center for Basic Metabolic Research at university of Copenhagen, leader of the international study.

Facts about the study
The research project was carried out by the EU-supported MetaHIT consortium and led by Professor Oluf Pedersen, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Science, University of Copenhagen.

The Danish partners were researchers from the University of Copenhagen, Technical University of Denmark and the Center for Prevention and Health, Glostrup Hospital.
For further information, please contact:

Professor Oluf Borbye Pedersen e-mail: oluf@sund.ku.dk, mobile: +45 29 38 25 26