Researchers found that changes in the composition of intestinal bacteria in type 2 diabetes are mainly related to obesity and the intake of dietary supplements and medications, not diabetes, as previously assumed.
People who are overweight have a significantly increased risk of developing type 2 diabetes. In fact, 86% of all patients with this type of diabetes are overweight. Genetic predisposition, lifestyles, such as diet and exercise practices, and the composition of the intestinal bacteria play a role in such metabolic diseases.
This is because the so-called intestinal microbiome helps people to process food and thus has a direct influence on metabolism. In overweight people, the diversity of intestinal bacteria is significantly reduced compared to people of normal weight. In particular, "good" intestinal bacteria, which fulfill functions for a healthy metabolism, are reduced. The same applies to overweight people with type 2 diabetes.
"Since type 2 diabetes usually occurs together with obesity, it is difficult to distinguish which changes in intestinal bacteria are specific only for type 2 diabetes and which for obesity," said Professor Andre Franke, Director at the Kiel-based Institute of Clinical Molecular Biology (German acronym: IKMB) and member of the Executive Board of the Precision Medicine in Chronic Inflammation (PMI) Excellence Cluster.
The researchers determined the intestinal microbiome from 1,280 stool samples. These came from so-called cohort studies, in which numerous test persons regularly collected biosamples from stools, urine, and blood, as well as information about their lifestyle, diseases, and medication intake.
The studies showed that the microbiome of overweight people - both with and without type 2 diabetes - was significantly different from that of people with normal weight. The difference between people with and without type 2 diabetes was relatively small. "The significant reduction in the species diversity of intestinal bacteria observed so far in these people is mainly due to obesity and less to diabetes," the scientists explained.
In addition, the team used the cohorts to investigate the influence of regularly taken drugs and dietary supplements on the intestinal microbiome. The result: drugs such as antihypertensives, analgesics, antidepressants, and antidiabetics as well as dietary supplements such as magnesium, vitamins, calcium and, above all, iron significantly altered the intestinal microbiome. "Such substances, which many people hope will have a health-promoting effect, change our intestinal bacteria. In this way, they also influence how we process our food and could possibly also play a role in metabolic diseases," said the researchers.
Both obesity and possible drug intake thus influence the intestinal bacteria of patients with type 2 diabetes. Using bioinformatic methods, the research team corrected the microbial changes observed in people with type 2 diabetes for this influence. In this way, they were able to identify individual bacterial species that are specifically more prevalent in type 2 diabetics.
They aim to understand more precisely what such microbiome changes actually do and which bacteria are the most important players in such changes. With this knowledge, they hope to be able to specifically influence diabetes' development.