Diabetes and the Gut Microbiome

February 22, 2021

One of the ways your diet affects your health status is by modulating the composition of your gut microbiota. It has been found that normal gut microbiota affects the development of the immune system, nutrient absorption, tissue generation and bone homeostasis metabolism. Therefore, a well-balanced diet is responsible for the control of microbial populations and thus in the prevention, management, and treatment of unwanted lifestyle-related diseases such as diabetes.

What is diabetes and how common is it?

Diabetes is a condition in which the body produces insufficient insulin, a hormone that keeps the blood sugar level in balance, or the body does not respond properly to insulin, resulting in high amounts of sugar in the blood. There are three main types of diabetes: Type 1 diabetes (usually inherited and cannot be prevented), Type 2 diabetes (the most common type of diabetes and can be prevented) and gestational diabetes (happens during pregnancy).

The prevalence of diabetes in Singapore is gradually increasing. One in seven Singaporeans is at risk of diabetes. Roughly 440,000 Singapore residents aged 18 years and above had diabetes in 2014 and this number is estimated to grow to 1,000,000 in 2050. Diabetes was the 4th and 8th most common condition of polyclinic attendances and hospitalisation respectively in 2014. Life years lost due to mortality and ill-health related to diabetes was the 4th largest among all diseases in 2010. The cost burden from diabetes, including medical expenses and productivity loss, is expected to rise from beyond $940 million in 2014 to $1.8 billion in 2050.

How does diabetes relate to the gut microbiome? 

Your gut microbiome is the collection of microbes in your gastrointestinal (GI) tract that may impact your immunity, your ability to extract energy from food, your metabolism, and more. These microbes play an important role in your health. The gut microbiome has been associated with pathophysiology of most chronic diseases. Type 2 diabetes is no exception to this rule. There is evidence for the effects of microbiota on glucose metabolism in both preclinical animal models of Type 2 Diabetes and in healthy animals.

Animal models have been useful in understanding factors that impact the gut microbiota, particularly with regard to high fat diets and obesity. A study model showed that dietary fat-induced changes to gut microbiome composition were independent of obesity.

High fat diets are notoriously associated with substantial compositional changes in gut microbiota, including reductions in both Gram-positive (e.g., Bifidobacterium spp.) and Gram-negative bacteria (e.g., Bacteroides).

A better diet with appropriate dietary adherence can improve insulin sensitivity and glycemic control, playing an important role in diabetes prevention. There is no single ‘gut healthy’ diet. But having a balanced diet that predominantly consists of a wide range of foods that are plant-based, high in fibre, or probiotic will promote a healthy gut with a diverse community of microbes, specifically healthy bacteria. This keeps your inner gastrointestinal ecosystem in shape.

What can I eat to keep my gut in check?

Healthy carbohydrates
During digestion, sugars (simple carbohydrates) and starches (complex carbohydrates) break down into blood glucose. Focus on healthy carbohydrates: Fruits, Vegetables, Whole Grains, Legumes and low-fat dairy products. Be sure to avoid less healthy carbohydrates, such as foods or drinks with added fats, sugars and sodium.

Fibre-rich foods
Dietary fibre includes foods that your body cannot digest or absorb. Fiber moderates how your body digests, helps control blood sugar levels and promotes satiety. Soluble fibre also functions as a prebiotic, readily fermented by gut microbes to produce Short-Chain Fatty Acids (SCFAs). Foods high in fiber include: Vegetables, Fruits, Nuts, Legumes and Whole Grains.

Heart-healthy fish
Fish such as salmon, mackerel, tuna, and sardines are rich in omega-3 fatty acids, which may prevent heart disease. It is recommended to consume these heart-healthy fishes at least twice a week. Avoid fried fish and fish with high levels of mercury, such as king mackerel.

Healthy fats
Foods containing monounsaturated and polyunsaturated fats can help lower your cholesterol levels. These include: olive oils, canola oils, nuts and avocados. But don’t overdo it, as all fats, healthy or not, are still calorie-dense foods!

Probiotics contribute to your gut by adding various strands of bacteria to populate the current bacteria in the gut. Probiotics can be consumed in the form of fresh food or supplements. Some of the food items include yoghurt, sauerkraut, tempeh, kimchi, miso, kombucha, pickles, and some cheeses. Some of the fermented foods that are listed here naturally contain probiotics.

Although a diet heavily impacts your gut, controlling your food intake may not be enough to prevent diabetes. Lifestyle intervention is equally important.

What else can I do? 

Avoid smoking
Smoking can harm your digestive system and affect the composition of your gut microbiome. Smoking can make certain conditions harder to treat and increases your risk for Crohn’s disease and gallstones.

Get moving!
Aim for at least 150 minutes of exercise at moderate intensity per week. A good gauge for moderate intensity is the level where you are able to have a conversation, but unable to sing.

Put down the bottle
Alcohol consumption places additional stress on the liver, which is responsible for metabolising alcohol.  Several studies suggest that systemic inflammation, like that caused by alcohol-provoked leaky gut, can influence the nervous system in several ways. If you drink alcoholic beverages, do so in moderation. Men should drink no more than two standard drinks a day, and women, no more than one. A standard alcoholic drink is defined as a can (330 ml) of regular beer, half a glass (100 ml) of wine or 1 nip (30 ml) of spirit.


  1. Conlon, M. A., & Bird, A. R. (2014). The impact of diet and lifestyle on gut microbiota and human health. Nutrients, 7(1), 17–44. https://doi.org/10.3390/nu701001
  2. Gurung, M., Li, Z., You, H., Rodrigues, R., Jump, D. B., Morgun, A., & Shulzhenko, N. (2020). Role of gut microbiota in type 2 diabetes pathophysiology. EBioMedicine, 51, 102590. doi:10.1016/j.ebiom.2019.11.051 
  3. HealthHub (2020). Alcohol and Health—Setting Your Drink Limits. Retrieved 8 January 2021, from https://www.healthhub.sg/live-healthy/182/alcohol_health_setting_drink_limits
  4. Riaz Rajoka, M. S., Shi, J., Mehwish, H. M., Zhu, J., Li, Q., Shao, D., … Yang, H. (2017). Interaction between diet composition and gut microbiota and its impact on gastrointestinal tract health. Food Science and Human Wellness, 6(3), 121–130. doi:10.1016/j.fshw.2017.07.003
  5. SingHealth. (2020). War On Diabetes. [online] Available at: <https://www.singhealth.com.sg/rhs/keep-well/war-on-diabetes> [Accessed 27 January 2021].
  6. Vrieze, A., Van Nood, E., Holleman, F., Salojärvi, J., Kootte, R. S., Bartelsman, J. F. W. M., … Nieuwdorp, M. (2012). Transfer of Intestinal Microbiota From Lean Donors Increases Insulin Sensitivity in Individuals With Metabolic Syndrome. Gastroenterology, 143(4), 913–916.e7. doi:10.1053/j.gastro.2012.06.031 

About the author

Leon is a final year student pursuing Nutrition, Health & Wellness at Singapore Polytechnic. He is an avid fan of Exercise Physiology and Sports Nutrition. He is currently serving his internship at AMILI.