The Bugs In Your Gut - Could They Cause Obesity or Diabetes?

Did you know that you have more bacterial cells inside your intestines than you have human cells in your entire body?  Not only that, but they house somewhere between 250 to 800 times more genes than we have human genes in our body.   Perhaps it's not so far out, then, for us to learn that these bacteria (called the 'microbiome') play an important role in our metabolism, and are very likely to contribute to the risk of both obesity and type 2 diabetes.

A wonderful Viewpoint article in JAMA (free to read online here) outlines what we know about this topic so far.

The microbiome has many important functions, including the production of important amino acids (protein building blocks) and vitamins, and they also help to degrade toxins.  The genes in these bacteria also produce hormones and inflammatory molecules that enter our circulation and effect our health.

These bacteria also play a role in how many calories we absorb from food, because they make enzymes that help us to digest polysaccharides, a type of carbohydrate.  Some types of gut bacteria are better at this than others, and studies have shown that people with obesity carry more of the carb-digesting bacteria (called Firmicutes) than people without obesity.  Interestingly, some studies have shown that when a person with obesity loses weight, particularly after bariatric surgery, the proportion of 'good' bacteria (called Bacterioides) increases relative to the 'bad' Firmicutes. Overall, the studies suggest that the gut bacteria may be both a cause and a consequence of obesity.

Along with the increased capacity to absorb carbs in people who carry more Firmicutes bacteria, so comes an increased risk of having not only obesity, but also type 2 diabetes.  Altered production of short chain fatty acids by gut bacteria, as well as low grade gut inflammation caused by chemicals made by the microbiome, also contribute to insulin resistance and diabetes risk.

So how does this play out in terms of treatment of obesity or diabetes? Well, some studies (mostly done in rodents, but some in humans too) have shown that manipulation of the gut microbiome by way of stool transplants (yep, transplanting poo), or perhaps by other modalities such as change in diet or probiotics, may be able to have an effect on the type of bacteria we have, but we are far from developing concrete treatment approaches.   However, as we learn more about our gut bugs and the genes they carry, we come steps closer to learning how we may ultimately be able to incorporate microbiome modification into our treatment options for obesity and metabolic syndrome.

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www.drsue.ca © 2017

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New Canadian Diabetes Association Clinical Practice Guidelines Update

While the full Canadian Diabetes Association (CDA) Clinical Practice Guidelines are formally updated every 5 years (with the next edition due in 2018), interim updates are published if new evidence emerges that is considered to be practice changing.  As such, the CDA has just released an interim update with revised recommendations, in light of the new cardiovascular outcome trial of a diabetes medication called liraglutide.

As blogged previously, in people with type 2 diabetes who were at high risk of cardiovascular disease, the liraglutide cardiovascular trial (called the LEADER trial) demonstrated that liraglutide reduced the risk of cardiovascular events by 13%.  Put another way: if 66 people are treated for 3 years with liraglutide, one cardiovascular event would be prevented.

In the LEADER trial, 81% of patients had a past history of established cardiovascular disease, while 19% of patients did not (but they were still considered to be at high risk of CV events due to their risk factors).  Subgroup analyses suggested that it was patients who had a history of established cardiovascular disease who had the reduction in risk with liraglutide. As patients had to be age 50 or older to be included in the study, we do not know if these findings apply to a younger population.

In the revised CDA Guidelines, liraglutide now joins another medication called empagliflozin, as medications to consider after metformin, in patients with type 2 diabetes and established cardiovascular disease, who are not at target blood sugar control.  As ongoing cardiovascular outcome trials of diabetes medications are completed and published, the CDA Guidelines will be updated accordingly.

I have pasted the new algorithm below, but the resolution isn't great - it's a little friendlier on the eyes here.

Disclaimer: I am a member of the Expert Committee for the writing of the Canadian Diabetes Association 2018 Clinical Practice Guidelines. 

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www.drsue.ca © 2016

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