Written by Xavier Toledo, Reviewed by Diana Licalzi, MS, RD, CDE
It is well known that type 2 diabetes is a multifactorial disease, meaning many factors contribute to its development. Perhaps less known is the gut microbiome's role in the onset and progression of the condition.
Research indicates, however, that improving the composition of the gut microbiome through probiotic supplementation may lead to better type 2 diabetes outcomes. In this article, we examine the potential health benefits of probiotic supplements for those living with type 2 diabetes.
What is the Gut Microbiome?
The human gastrointestinal (GI) tract (sometimes referred to as the “gut”) contains trillions of microorganisms and their associated genes, collectively referred to as the microbiome. These microorganisms (e.g., bacteria, archaea, etc.) are so abundant they outnumber our human cells!
Our microbiome plays a critical role in our overall health and can even influence the course of numerous conditions, including type 2 diabetes . For example, the gut has both “good” and “bad” microorganisms, but an unequal balance between the two may lead to increased pathogenic bacteria, inflammation, and worsen type 2 diabetes .
What’s more, a groundbreaking discovery revealed differences between the gut microbiomes of diabetic and non-diabetic individuals. These studies revealed an imbalance in the gut microbial composition of diabetic individuals, known as microbial dysbiosis .
Improving the composition of the gut microbiome may therefore lead to better type 2 diabetes outcomes. The gut microbiome can be altered by our everyday activities, including through our diet, supplements like probiotics, and even exercise. For an in-depth review of how diet influences our gut microbiome, read our blog on the topic.
What Are Probiotics?
Probiotics refer to live microorganisms that can help replenish the good bacteria existing within our gut. People often purposefully consume probiotics with the hopes of bettering their health. These health benefits generally result from improvements in the composition of the gut microbiome.
So, how can we incorporate probiotics into our diets? There are several notable sources. These include our food (e.g., yogurt, tempeh, etc.), the environment (e.g., dirt, pets, etc.), and supplements. In this article, we’ll focus on probiotic supplementation and its impact on type 2 diabetes.
Can Probiotics Improve Type 2 Diabetes?
Over the years, several studies have examined the relationship between probiotic supplements and diabetes-related markers, including fasting blood glucose (FBG), HbA1c, and insulin resistance.
A 2020 meta-analysis examined the effects of probiotics on diabetes biomarkers in a total of 15 randomized control trials (RCTs), which included over 900 patients with type 2 diabetes. The researchers found that probiotic supplementation significantly improved HbA1c, fasting blood glucose, and insulin resistance . The authors concluded that the “ results were quite robust and stable,” indicating grounds for the use of probiotics as an additional treatment option for type 2 diabetes.
Another 2020 meta-analysis consisting of 32 RCTs revealed similar findings. Probiotic supplements reduced fasting glucose, HbA1c, and fasting insulin levels. When looking at fasting blood glucose specifically, both short-term (8 weeks or shorter) and long-term (12 weeks or more) studies showed probiotic supplementation significantly decreased FBG levels.
What’s more, the researchers examined changes in other health markers, including positive effects on total cholesterol, triglycerides, and CRP (a marker for inflammation) .
A 2021 systematic review and meta-analysis examined the change in glucose levels before and after taking probiotic supplementation. The outcomes also revealed that probiotics lowered FBG in both the short-term and long-term, and those with glucose levels above 130mg/dL tended to see more remarkable results . Lastly, several other studies have found that probiotics positively impact fasting insulin levels .
There are many possible reasons why probiotics may impact blood sugar levels. One common hypothesis is that probiotics may affect the metabolites produced by the gut microbiome. Examples of these metabolites include the short-chain fatty acids butyrate and acetate—both of which have been associated with changes in glucose metabolism . However, like most things in the evolving field of nutrition, more research is needed to elucidate the role probiotics play in improving type 2 diabetes.
What is the Best Probiotic for Type 2 Diabetes?
Like most supplements, many probiotic options are available on the market. Because of this, it can be overwhelming to decide which one is best for you.
One of the most important differences between probiotic supplements is the ingredients—notably, which probiotic strains they contain. There are hundreds of unique strains of probiotics, and each of them performs different functions in the body. Although the verdict is still in the air as to which probiotic strains are best for those with type 2 diabetes, it is crucial to ensure that your probiotic supplement meets the following general criteria:
Adequate Amount of Probiotics: When taking a probiotic, the goal is for the “good” bacteria to form colonies within your gut. Once they’ve formed a colony, they’re able to jump into action and start changing your gut microbiome for the better. To give yourself the best chance of forming these colonies, you need to ensure that your supplement has at least one million colony-forming units (or CFUs). This is considered the minimum amount of CFUs to provide therapeutic benefits .
Live Cultures: If you’re taking probiotics in hopes of improving your health, your probiotics must be alive when you take them. There are several ways that you can ensure this. First, check the expiration date to ensure the probiotics are not expired. Additionally, check the storage instructions. Some probiotic supplements may require refrigeration, for example.
Is It Safe For Diabetics to Take Probiotics?
Since probiotic supplements are composed of the “good” bacteria that already exist within our body, they are generally considered safe for most individuals. However, you should always check with your care team (e.g., your physician, dietitian, or other qualified health professional) when considering a new supplement.
Some groups (such as those who have recently undergone surgery, the immunocompromised, and the critically ill) should be cautious about probiotic supplementation. However, no safety concerns have been widely reported regarding probiotics for the diabetic community. As a program member, we’d be happy to assess your situation and offer more personalized guidance on whether probiotic use is wise for you.
Final Thoughts on Probiotics for Type 2 Diabetes
Supplements alone, including probiotics, will never treat or cure type 2 diabetes. Proper diet and other lifestyle modifications are imperative to reversing or delaying the progression of this condition. However, with many individuals looking to complement their efforts in treating diabetes, probiotic supplementation may be a practical and effective addition. With several studies showing the positive effects of probiotics, using them as a therapeutic agent for type 2 diabetes seems promising. Plus, in addition to their potential anti-diabetic properties, probiotics have also been linked to improvements in blood lipid levels, blood pressure levels, and overall metabolic control (all of which play an important role in diabetes management) .