Can Blood Sugar Levels Affect Your Immune System?

Published: Dec. 29, 2025

6 min read

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Blood sugar levels affect the entire body in complex ways. The sugar that’s in our body, also known as glucose, comes from the foods and drinks we consume and it’s an essential source of energy for our cells.¹ However, changes in glucose levels that can happen when you’re living with diabetes may cause issues with the way certain parts of the body work, including the immune system.¹ Both hyperglycemia, high glucose, and hypoglycemia, low glucose, can directly impact the immune system’s ability to function properly. Individuals living with diabetes are more likely to experience hyperglycemia and hypoglycemia than those who do not live with the condition and are at greater risk of getting sick or having infections.^2-5

Understanding the Role Your Immune System Plays in Your Body

The immune system protects the body from bacteria, viruses, fungi, and parasites that can cause infections and make you sick. It keeps germs out of your body and kills them if they get inside. It also works to destroy cancer cells and helps heal wounds and repair damage.⁶ The immune system is a complex network that includes organs like the lymph nodes, spleen, thymus, and tonsils, as well as the skin and the mucous membrane that lines the nose, throat, lungs, and digestive tract—your body’s first lines of defence against invaders.⁶ White blood cells and proteins called antibodies and cytokines work together to orchestrate and execute attacks on unwanted guests. White blood cells are like warriors that play a central role in identifying threats, carrying out attacks, and communicating with the rest of the immune system..⁶

Some white blood cells that are part of the immune system are pre-programmed to deal with invaders that shouldn’t be in your body. This is known as innate immunity.^6,7 There are other white blood cells, called lymphocytes, that learn from being exposed to new germs and threats you encounter throughout your life, known as acquired or adaptive immunity.^6,7 Vaccines work to train these white blood cells to recognize new threats and make antibodies that can destroy them.⁶

In most situations, the immune system easily differentiates between what belongs in the body and what doesn’t. Sometimes, the immune system overreacts to things that aren’t necessarily threatening, which is why people experience allergies.⁶ The immune system can also mistakenly attack healthy parts of the body and cause autoimmune diseases that include type 1 diabetes (T1D), rheumatoid arthritis (RA), lupus, and Crohn's disease.⁸

Type 1 Diabetes and the Immune System

T1D happens because of an autoimmune event where the immune system mistakenly attacks cells in the pancreas called beta cells, which produce the hormone insulin.⁹ This attack destroys the beta cells, and the body can no longer produce the insulin it needs to absorb glucose for energy.^1,9 Doctors are still working to understand why this autoimmune event happens, but research suggests that family genetics and environmental factors play a role.⁹

Those living with T1D may also be more likely to experience other autoimmune conditions, such as autoimmune thyroid diseases and celiac disease, because the autoimmune event that causes T1D may also affect other parts of the body.¹¹ Living with T1D does not necessarily lead to having a weaker immune system. However, issues with blood sugar management that arise due to T1D can make it harder for the immune system to defend against illness and infection.²

Type 2 Diabetes and the Immune System

Type 2 diabetes (T2D) is not caused by an autoimmune event. It develops as cells in the body become resistant to the insulin the pancreas produces and can no longer absorb glucose properly. Over time, the beta cells can get damaged and stop producing enough insulin.¹¹

However, like those living with T1D, people living with T2D may face challenges managing their glucose levels. This can have an impact on the immune system functions and cause changes in the cells that are responsible for the body’s immune response.³

There is also a relationship between the immune system, insulin resistance, and fat in the body. Experiencing obesity is one of the risk factors that can contribute to the development of T2D.¹²Obesity can cause chronic inflammation, which is when the immune system stays on high alert even if there is no immediate threat from the outside.¹⁴Chronic inflammation has been linked to the development of insulin resistance present in T2D.¹⁴

How Does Blood Sugar Affect the Immune System?

Experiencing high blood sugar, or hyperglycemia, can weaken the immune system.² Having a lot of glucose in the blood can cause the immune system to launch an inflammatory response.^2,3 Because the immune system is working overtime dealing with the perceived threat, it can’t deal with incoming invaders like bacteria and viruses.² High blood sugar levels can also reduce the body’s ability to heal wounds, making it more vulnerable to infections.²

Low blood sugar, or hypoglycemia, may also lead to inflammation.^4,5Studies have shown that the body can launch a prolonged inflammatory response after a period of hypoglycemia that can last for several days. Even individuals who do not live with diabetes can experience inflammation after their blood sugar goes low.^4,5

Because diabetes and blood sugar can impact immune function, people living with the condition may experience common illnesses like colds more often and have more severe symptoms than those who do not live with it.² They are also at greater risk of experiencing serious symptoms if they catch illnesses like the flu, pneumonia, and COVID-19.² Individuals living with diabetes may also be more likely to experience skin infections—including Staph infections or boils—urinary tract infections, and cold sores caused by the herpes simplex virus 1.^2,3

Supporting Your Immune System when You Live with Diabetes

Our immune system is extremely complex, and there isn’t a proven way to “boost” your immune function.¹⁵ However, you can take steps to help make your immune system’s job a little easier. It’s important to talk to your doctor and diabetes care team about how to support your immune system and protect yourself from getting sick. Making healthy choices as part of your diabetes self-management routine can set you and your immune system up for success. This can include:6,¹⁵

Eating nourishing foods, including fruits, veggies, lean protein, and healthy fats to ensure you get enough essential nutrients.
Getting in regular movement you enjoy. Diabetes Canada recommends aiming for 150 minutes of physical activity each week.
Prioritizing sleep and working to manage or reduce stress.
Avoid or quit smoking.

It’s also a good idea to reduce your chance of getting an infection.⁶ You can do this by washing your hands regularly and maintaining a foot care routine to clean and check your feet and legs for blisters and wounds.^15,16 Be sure to cook meat thoroughly and wash your produce before eating it.¹⁵ You could consider wearing a mask when you use public transport to avoid catching colds, the flu, and COVID-19. Speak with your doctor about keeping up with vaccines. Health Canada recommends that everyone 9 years of age and older get the flu vaccine every year.¹⁷

Managing Glucose to Help Strengthen Your Immune System

Reducing hyperglycemia and hypoglycemia can help limit inflammation in the body and make it a little easier for the immune system to function effectively.2-5 You can work with your doctor and diabetes care team to create a plan and develop habits that empower you to spend as much time as possible in your ideal glucose range (generally defined by Diabetes Canada as being between 3.9 and 10.0 mmol/L¹⁸). Spending more time in range can help you lower your A1C, which can indicate that you’re experiencing hyperglycemia and hypoglycemia less often.[19]

There are many factors that can cause glucose levels to go high or low. One way to learn what leads to changes in your glucose is to use a continuous glucose monitoring (CGM) system like the Dexcom G7 CGM System. With Dexcom G7, you can see your glucose readings in real time on your compatible smartphone, smartwatch, or handheld receiver.* Dexcom G7 also connects to Dexcom Clarity, which can show you patterns in your glucose over time. This can give you and your doctor insight into how your diabetes management plan is working, empowering you to make more informed decisions around your habits and treatment options to better support your immune system. Using Dexcom CGM Systems, including Dexcom G7, is proven to lower A1C and increase time in range, which can help you take care of your overall health.^20-24

Learn more about using Dexcom G7 to lower A1C.

* For a list of compatible devices, please visit www.dexcom.com/compatibility.

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2 Yor Immune System and Diabetes. Centers for Disease Control and Prevention. May 15, 2024. Accessed November 28, 2024. https://www.cdc.gov/diabetes/diabetes-complications/diabetes-immune-system.html
3 Vaibhav, et al. Health Sciences Review. 2024;13:100201
4 Iqbal A, et al. Diabetes. 2022;71(12):2483-2485
5 Drummond JB, et al. Brain Behav Immun. 2018;73:41-50.
6 Immune System. Cleveland Clinic. Reviewed October 20, 2023. Accessed November 28, 2024. https://my.clevelandclinic.org/health/body/21196-immune-system
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Accessed November 28, 2024. https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-immune-system
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10 Popoviciu MS, et al. J Pers Med. 2023;13(3):422. Published 2023 Feb 26
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12 Assess your risk of developing diabetes. Diabetes Canada. Accessed November 28, 2024. https://www.diabetes.ca/type-2-risks/risk-factors---assessments
13 Inflammation. Cleveland Clinic. Reviewed March 22, 2024. Accessed November 28, 2024. https://my.clevelandclinic.org/health/symptoms/21660-inflammation
14 Wu H, et al. Circ Res. 2020;126(11):1549-1564
15 How to boost your immune system. Harvard Health Publishing. March 28, 2024. Accessed November 28, 2024. https://www.health.harvard.edu/staying-healthy/how-to-boost-your-immu
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16 Foot care: a step towards good health. Diabetes Canada. 2018. Accessed November 28, 2024. https://www.diabetes.ca/DiabetesCanadaWebsite/media/Managing-My-Diabetes/Tools%20and%20Resources/foot-care.pdf?ext=.pdf
17 Flu (influenza): Get your flu vaccine (flu shot). Government of Canada. Updated October 10, 2024. Accessed November 27, 2024. https://www.canada.ca/en/public-health/services/diseases/flu-influenza/get-your-flu-shot.html
18 Imran AS, et. al. Can J Diabetes. 2018:42(S42–S46)
19 Time in Range. Breakthrough T1D. Accessed November 28, 2024. https://breakthrought1d.ca/time-in-range/
20 Beck RW, et al. JAMA. 2017;317(4):371-378
21 Beck RW, et al. Ann Intern Med. 2017;167(6):365-374
22 Martens T, et al. JAMA. 2021;325(22):2262-2272
23 Laffel LM, et al. JAMA. 2020;323(23):2388-2396
24 Welsh JB, et al. J Diabetes Sci Technol. 2024;18(1):143-7

View all

Can Blood Sugar Levels Affect Your Immune System?

Understanding the Role Your Immune System Plays in Your Body

How Does Blood Sugar Affect the Immune System?

Supporting Your Immune System when You Live with Diabetes

Managing Glucose to Help Strengthen Your Immune System

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