Most of you likely know someone or will know someone who has type 2 diabetes. Not only does it account for around 90% of all diabetes, it affects around 8% of the world’s population. When you have type 2 diabetes, your body essentially does not recognize insulin, the protein that tells the cells in your body to take up glucose from your blood. Your cells don’t get enough sugar and cannot function properly. Furthermore, all that extra glucose floating around in your blood can also have devastating effects.
Its prevalence has been increasing, along with the rising obesity epidemic. This is because obesity and similar diet and lifestyle choices often cause type 2 diabetes. There are other causes, such as genetics, gender, and certain bacteria in the gut microbiota as well. The bacterial species Bacteroides and Prevotella have been connected with type 2 diabetes, and this is important for a study that was recently done with medication for type 2 diabetes.
The medications used in the study were Glipizide, which acts by trying to ramp up your body’s insulin production, and Acarbose, which stops more complex sugars from being broken down thus making sure less glucose is absorbed into your blood. While Glipizide would have no effect on the bacteria in the users gut, Acarbose would allow more complex sugars to pass farther into the intestine and thus provide different molecules for bacteria to chow down on. This key difference was vital for explaining the effects the researchers saw.
Patients treated with acarbose had increased amount of Lactobacillus and Bifidobacterium, and depleted amounts of Bacteroides. Clearly Bacteroides aren’t that big of a fan of those new complex sugars. This change in bacterial composition clearly also changed the genes involved in bile acid metabolism. This is important because specific types and ratios of bile acids are heavily involved in metabolism. The change in genes, changed the amount and type of bile acids present in the patients. This change provided the patients with a lot of benefits, including lower blood sugar and increased responsiveness to insulin.
The researchers also noticed that within the group of patients treated with Acarbose, those with a higher level of Bacteroides than Prevotella exhibited greater improvement of metabolic parameters, and thus lowered the burden of type 2 diabetes. These findings could potentially show that knowledge of a the bacteria swimming around in a type 2 diabetic’s gut would allow the prediction of which medication would have a greater affect on them.
Metabolic diseases such as diabetes and obesity are becoming a major concern for all countries. In developing countries such as South Asia, which are affected by the highest rate of population growth, the social system cannot afford the corresponding expenses. One of the major consequences linked to the occurrence of these metabolic diseases is the rapid increase in cardiovascular events leading to death (1). Therefore, in Western countries, where metabolic diseases are firmly established, as well as in Eastern countries, where diabetes and obesity are strongly emerging, there is a crucial need to identify the risk factors of diabetes and obesity and to find new therapeutic targets.
What is Type I Diabetes?
In Type I Diabetes, the body’s immune system attacks part of its own pancreas. In fact, the immune system ,more specifically T cells — which are a type of immune cells that destroys foreign particles, recognizes the insulin-producing cells in the pancreas as foreign and destroys them. This type of attack is known as autoimmunity. The insulin-producing cells, also called “islets”, are the cells that sense glucose in the blood and, in response, produce the necessary amount of insulin to normalize blood sugars. Without insulin, sugar builds up in the blood. If left untreated, the high level of blood sugar can damage the eyes, kidneys, nerves, and heart (2).
Gut Microbiota and Diabetes
A high incidence of Type I Diabetes has now plagued developed countries for several decades, where environmental conditions have dramatically changed (3).
Recent research has shown the critical role of the gastrointestinal microbiota in both the protection and development of Type I Diabetes. The discovery of the role of intestinal microbiota came from the observation that the incidence of spontaneous Type I Diabetes in a certain type of mouse colony can be affected by the microbial environment in the animal housing facility or by exposure to microbial stimuli such as injection with mycobacterium (a type of bacteria) or various microbial products (4).
Studies on rats have shown that bacterial species such as Lactobacillus johnsonii and Lactobacillus reuters prevented the development of Type I Diabetes. Moreover, observations following the administration of antibiotics in Type I Diabetic rat models showed that the occurrence of the disease was reduced, strengthening the hypothesis that a specific intestinal microbiota composition can induce autoimmune diseases, including Type I Diabetes.
Thus, prevention of Type I Diabetes can, in the future, be based on interventions targeting the gut microbiota.