How the gut microbiota contributes to type 2 diabetes: What we already know

With 425 million people in the world living with diabetes, chances are you have a family or friend who has this chronic disease. One of the primary risk factors for the development of type 2 diabetes is obesity. Changes in the gut microbiota have been implicated in the emergence of both obesity and type 2 diabetes in humans. This therefore begs the question: could changing the gut microbiota trigger, prevent or manage type 2 diabetes? And, if so, how?

A new review led by Dr. Victor Gerdes and colleagues from MC Slotervaart and the Academic Medical Center at the University of Amsterdam in the Netherlands summarizes key human and animal studies, analyzing the role of the gut microbiota in obesity and type 2 diabetes.

Several studies discussed in the review have found that obesity-related changes in the gut microbiota are associated with low grade inflammation, which supports a close link between the immune and metabolic systems throughout the gut microbiota. These changes appear to be attenuated by dietary interventions, with human studies showing that a fiber-enriched diet may improve insulin resistance in both lean and obese subjects. However, not everyone responds to dietary interventions in the same way.

The gut microbiota might explain why the impact of nutritional interventions varies among individuals, even when they eat the same food. A study published in 2015 by a team from the Weizmann Institute of Science in Israel showed how the gut microbiota may have an impact on blood sugar control, with researchers finding that a person’s gut microbiota could predict how quickly their blood sugar would increase in response to eating a particular food. These noteworthy findings therefore suggest that modifying a person’s gut microbiota may mean they can better control their blood sugar.

Furthermore, similarities between bacterial composition and obesity-related changes have been observed in several studies included in the review, though primarily in animal models. Changes such as the total number of bacteria, bacterial diversity and bacterial function in the gut appear to correlate not only with obesity, but also with low grade inflammation, thus driving insulin resistance.

Gerdes and colleagues explain that researchers have begun to explore how changing the microbiota to resemble the composition of a lean individual would impact blood sugars and insulin resistance. Several studies stated in the review have attempted to alter bacterial composition through probiotics, prebiotics and fecal microbiota transplants, and found that the gut microbiota can be modulated to reduce hunger hormones, weight and fat mass, therefore helping to better control blood sugar.  However, most of the research on modifying the gut microbiota has come from animal model studies and has not been reproducible in humans. This is probably because animals have a different gut microbiota and physiology than humans, along with confounding factors in human studies that include differences in ethnicity, environment and diet.

These promising findings highlight the need for larger-scale human studies to validate what might actually work in humans, but they also provide hope for the role of targeting the gut microbiota in order to manage type 2 diabetes. Future research will surely look at the exciting possibility of developing new therapeutic agents to alter insulin resistance, obesity, appetite and, ultimately, the possibility of disease reversal.

 

References

Aydin, Ö, Nieuwdorp, M., & Gerdes, V. The Gut Microbiome as a Target for the Treatment of Type 2 Diabetes. Curr Diab Rep. 2018; 18(8):55. doi:10.1007/s11892-018-1020-6.

Andrea Hardy
Andrea Hardy
Registered Dietitian, Andrea Hardy from Calgary, Canada specializes in gastrointestinal disorders and the gut microbiome. She is recognized as Canada’s gut health dietitian – educating health care professionals and the public on the pivotal role nutrition plays in gut health. You can find her at Ignite Nutrition, or on Twitter (@AndreaHardyRD).