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Gut microbiome research indicates new bacteria and metformin associations

Photograph of a researcher in the lab.
Marju Orho-Melander is one of the lead authors of the article in Nature Communications, which is based in large-scale analyses of faeces and blood samples. Photograph: Petra Olsson

A large-scale faeces and blood sample study indicates strong associations between gut bacteria and metabolites in the blood. Among other findings, the research team behind the study has identified new associations between a common type 2 diabetes drug and the gut microbiome. The study was led by researchers at Uppsala University and Lund University.

The role of the gut microbiome in disease and health has become an increasingly important research area. A new article published in Nature Communications improves our understanding of the connection between gut bacteria and metabolites in the blood. A metabolite is a substance in the body that has evolved through a chemical reaction. Endogenous and exogenous substances, including drugs, can be transformed into metabolites. The study is based on faeces and blood samples from 8,583 participants in the Swedish population study SCAPIS (Swedish CArdioPulmonary bioImage Study). 

“Our results indicate there is a strong link between the gut bacteria and metabolites in the blood. In this study we were able to identify a multitude of new associations because the study was so much larger than previous studies and because the samples were so well-characterized”, says Tove Fall, professor of molecular epidemiology at Uppsala University and corresponding author of the study.

Studies on metformin

The research team at Uppsala University and Lund University has also studied the associations between the drug metformin and the gut microbiome in participants who were treated with the drug. Treatment with metformin is common in people with type 2 diabetes and it can lower blood sugar levels and prevent complications from diabetes. Some individuals experience side-effects from metformin, such as stomach problems. As part of this new study, the researchers have identified 462 bacterial species that are associated with the drug.

“Our findings confirm previous research which has shown that metformin treatment can be associated with changes in the gut microbiome composition. We have also found new associations between metformin and the gut microbiome and have observed that individuals who are treated with metformin have higher levels of certain bacteria and lower levels of other bacteria than individuals who are not receiving the treatment”, says Marju Orho-Melander, research group leader in diabetes and cardiovascular disease at Lund University Diabetes Centre (LUDC) and one of the main authors of the study.

The results can make way for studies into why certain individuals with type 2 diabetes experience stomach problems when on metformin while others do not, based on the makeup of their gut microbiome. 

“Eventually, it may be possible to develop new probiotics that patients with stomach issues can take together with metformin to tolerate the drug better”, says Marju Orho-Melander, professor of genetic epidemiology at Lund University.

Openly available database

To maximize the availability of data from this study, the researchers have made the results available for free online using secure protocols. The team sees this as their contribution to the growing understanding of how the gut microbiome affects people’s health. Marju Orho-Melander believes that the database will provide diabetes researchers with new opportunities to study the disease.

“We know that the gut microbiome and metabolites are of great importance to type 2 diabetes and obesity. This database can be used in future studies by us and other researchers. The data we have collected can also be combined with other types of data, which makes it possible for us to study how gut microbiome composition and metabolites affect possible future disease progression”, says Marju Orho-Melander. 

Link to the press release from Uppsala University 


The main funding body of the Swedish CArdioPulmonary bioImage Study (SCAPIS) is the Swedish Heart-Lung Foundation. SCAPIS is also funded by the Knut and Alice Wallenberg Foundation, the Swedish Research Council, Vinnnova, the Swedish research council and the participating universities (Uppsala University, Umeå University, Linköping University, Lund University, University Gothenburg, and Karolinska Institutet) and the university hospitals (Uppsala University Hospital, Norrland University Hospital, Linköping University Hospital, Skåne University Hopsital, Sahlgrenska University Hospital, and Karolinska University Hospital).

Financial support for this project was provided by the European Research Council, the Swedish Research Council, the Swedish Heart-Lung Foundation, the Göran Gustafsson foundation, Axel and Signe Lagerman’s foundation, the A.L.F. governmental grant, the Novo Nordisk Foundation, the Swedish Diabetes foundation the Swedish Foundation for Strategic Research, and Formas.

Portrait of researcher.


Marju Orho-Melander, professor of genetic epidemiology at Lund University

+46 70 739 82 89
+46 40 39 12 10

marju [dot] orho-melander [at] med [dot] lu [dot] se

Marju Orho-Melander’s profile on the Lund University research portal


Study facts

Topic: Endocrinology, metabolism
Research area: Clinical research, epidemiological research
Type of publication: Peer-reviewed publication
Study design: Quantitative study, research-initiated study, statistical connection
Observational study: Cross-sectional study, cohort study
Number of individuals in the population study: 8,583 

Link to the study in Nature Communications

Link to the openly available database (


Diabetes is one of our main endemic diseases. The strategic research area EXODIAB (Excellence of Diabetes Research in Sweden) aims to develop new treatments and medicines that can prevent, delay or cure the disease and its complications. Another important goal is to improve the basis on which individually tailored care and treatment of patients with diabetes is delivered. 

EXODIAB integrates research from various areas with clinical and population studies (epidemiology), creating platforms for collaborations between academia and industry. 

The research is being developed in a collaboration between Lund University and Uppsala University. The strategic research area involves around 300 employees at Lund University.