In humans, there appears to be certain microbial bacteria that increase the risk of diabetes. Conversely, other microbes appear to be protective against it.
So said, Robert E. Ratner, MD, FACP, FACE, during his plenary lecture Thursday morning. Dr. Ratner, who is Chief Scientific and Medical Officer of the American Diabetes Association and an AACE charter member, reviewed the increasing body of research on the microbiome and the role it plays in diabetes.
He began by showing just how many microbial cells and genes exist in and on the human body. While there are about 10 trillion human cells in our bodies, there are about 100 trillion microbial cells. And while these cells are everywhere, Dr. Ratner focused his discussion on the cells found in the terminus of the gastrointestinal tract.
“Yes,” he said. “We’re going to spend the next 40 minutes talking about crap.”
Dr. Ratner reviewed a study of non-obese diabetic mice to illustrate how gut bacteria are associated with diabetes. Of the mice, 80 percent of the females developed diabetes compared to only 20 percent of the males. However, when feces from the females were transferred to the males, the males developed diabetes at rates similar to the females.
Studies using bio-bred rats have also shown links between gut bacteria and diabetes development.
“One of the interesting things about the BB rat is that it has a particular microbiome,” Dr. Ratner said. “The wild type BB diabetes-prone rat develops diabetes at a rate of 60 percent in 20 weeks. However, if you take that same BB diabetes-prone rat and identify a particular bug in their GI tract — in this case lactobacillus johnsonii — very few of them develop diabetes. In fact, only about 20 percent ever get diabetes. In contrast, if you look at another bug — in this case lactobacillus ruterii — you see increased probability of developing diabetes. So again, it’s gene-environment interaction that’s leading to disease.”
Dr. Ratner reviewed results from several other studies looking at the microbiome in humans, including a study showing links between certain bacteria and type 2 diabetes as well as a study showing how diet changes and weight loss can change the ratio of firmicutes to bacteroides bacteria. After a year of diet and weight loss, subjects had bacteria ratios similar to lean control subjects.
Dr. Ratner also looked at data on the bacterium akkermansia muciniphila.
“Subjects with adequate levels of akkermansia muciniphila maintain a gut barrier,” he said. “The mucus layer is thicker. The generation of antimicrobial peptides is greater. Bio-optic lipids are greater. Endotoxemia goes down. Insulin sensitivity goes up. Hepatic glucose production goes down. Fat oxidation goes up. Fat mass goes down and so does inflammation.”
While these studies and others offer exciting findings, Dr. Ratner said attendees must remember they’re all association studies.
“Bugs really do have an effect to protect us in the GI tract,” he said. “Ultimately… what we really need to do is talk about causation. That’s where studies in the microbiome are really deficient.”