Does diabetes weaken your immune system? The Centers for Disease Control and Prevention (CDC) says it can. CDC explains that high blood sugar adds stress to your body and makes nearly every system work harder, including the white blood cells of your immune system, so your immune system might be weakened and less effective. CDC says that means diabetes increases your chances of getting sick, staying sick longer, or getting severely sick.
Key takeaways
- CDC says people with diabetes can have more frequent respiratory infections, flu, pneumonia, urinary tract infections, and skin infections, and may heal more slowly.
- A 2021 research review says chronic high blood sugar is a key driver of problems in neutrophils, white blood cells that fight germs.
- CDC says people with diabetes might not be more likely to catch COVID-19 or flu, but are more likely to get severely ill, especially when blood sugar is not well managed.
- Illness can raise blood sugar, and fever, sweating, and poor appetite can lower it. Check more often when you are sick.
- CDC lists blood sugar in range, fruits and vegetables, activity, hand washing, stress care, sleep, and vaccines as ways to stay healthy.
How Your Immune System Works
CDC describes the immune system in layers. Your skin is the first line of defense because it keeps germs out. The second layer is a type of white blood cell, called lymphocytes, that circulate in your body looking for threats such as bacteria, viruses, toxins, and fungi. Once your immune system recognizes a germ, it fights it, often without you noticing.
Your immune system also builds immunity. CDC says that once it has learned to fight a virus, it often remembers how to do it again, so you may have fewer or no symptoms the next time. Vaccines work by giving your immune system instructions on how to fight a virus, which protects you from getting severely ill. Our guide to vaccines for people with diabetes covers which ones are recommended.
How Diabetes Affects the Immune System
CDC says high blood sugar can also trigger inflammation, a protective immune response that can damage internal organs over time. When your immune system is working harder because of inflammation and may already be weakened, it is harder to fight off infections.
Research reviews describe what may be going on at the cell level:
- Neutrophils. A 2021 review in Frontiers in Immunology says neutrophils are white blood cells that handle germs, and that their responses to infection are dysregulated in diabetes, mostly because of persistent high blood sugar. The authors report that moving toward an infection, engulfing germs, and making germ-killing chemicals inside the cell are decreased in diabetes, which weakens the response. At the same time, some inflammatory pathways are turned up, which can damage the body and keep inflammation going.
- Inflammation and metabolism. A 2020 review says inflammation and metabolic changes such as insulin resistance and obesity affect each other, and that the impaired immune system together with metabolic imbalance increases the chance of infection.
- Many possible causes. A 2022 review says several mechanisms have been proposed for why people with type 2 diabetes are more likely to develop severe respiratory infections. They include immune problems that were already present, insulin resistance, diet quality, and interactions with diabetes medicines or other conditions.
Researchers are still working out how much each factor matters. The practical message from CDC and ADA is the same: higher blood sugar makes it harder for the body to fight infections.
Which Infections Are More Common?
CDC says research shows people with diabetes can have more frequent illnesses of these kinds, and that it may take longer to heal from illnesses, cuts, and wounds.
| What CDC lists | Where to read more |
|---|---|
| Respiratory tract infections | Vaccines for people with diabetes |
| Influenza (flu) | Should diabetics get a flu shot? |
| Pneumonia | Do diabetics need the pneumonia vaccine? |
| Urinary tract infections | Can recurrent UTIs be a sign of diabetes? |
| Skin infections | How diabetes affects your skin |
| Slower healing of cuts and wounds | Why diabetics heal slowly |
Foot wounds deserve special attention. Our guides on caring for cuts and scrapes and diabetic foot ulcers explain what to watch for.
Do You Catch More Germs, or Get Sicker?
It depends on the germ. CDC says people with diabetes might not have a higher risk of getting infected with COVID-19 or flu, but research shows they have an increased risk of severe illness from these viruses, especially if blood sugar is not well managed.
For RSV, ADA says that if you have diabetes, you are more likely to get RSV and to have serious problems from it. ADA says this may be because diabetes weakens the immune system so it cannot fight germs as well. CDC's vaccine fact sheet (March 2020) adds that people with diabetes are at increased risk of death from pneumonia, bloodstream infections, and meningitis.
CDC's flu page says people with type 1, type 2, or gestational diabetes are at higher risk of serious flu complications even when diabetes is well managed, and that about 30% of adults hospitalized with flu have diabetes.
Why Being Sick Changes Your Blood Sugar
CDC says that if you get sick, you may notice your blood sugar is higher than usual, because your immune system releases hormones that can increase blood sugar temporarily. CDC also says some cold and flu medicines can raise blood sugar. On the other hand, fever, sweating, and poor appetite can cause low blood sugar.
That is why CDC says to monitor your blood sugar closely when you are ill. CDC's sick day page says to check your temperature each morning and evening, because a fever may be a sign of infection. Our guide to diabetes sick day rules covers what to keep on hand, and our guides on diabetic ketoacidosis and ketones in urine explain why ketone checks can matter during illness.
Type 1 and Type 2
CDC says type 1 diabetes is an autoimmune disorder, in which the immune system mistakenly attacks part of the body, and that people with type 1 diabetes may have weaker immune systems for this reason. The 2021 review above includes both type 1 and type 2 diabetes and says chronic high blood sugar is a basic abnormality in both. Our guide to whether type 2 diabetes is an autoimmune disease explains the difference between the two types.
What Helps
CDC lists these steps to help your immune system work well:
- Keep blood sugar in your target range. CDC says this can help prevent short- and long-term illnesses and help you recover sooner if you do get sick.
- Eat plenty of fruits and vegetables. CDC says they are rich in vitamins and minerals that help your immune system work well, and suggests eating many colors. Talk to your doctor before taking any vitamin or mineral supplements.
- Be physically active. CDC says activity can help you manage blood sugar and keep your immune system strong in case you get sick.
- Wash your hands. Germs spread from surfaces you touch every day.
- Manage stress. CDC says that when stress is high, your immune system may have a harder time fighting infections, and stress can also raise blood sugar.
- Get enough sleep. CDC says that if you regularly get less than 7 hours of sleep, your diabetes will be harder to manage, and too little sleep can make it harder for your immune system to fight infections.
- Get vaccinated. CDC says vaccines are especially important for people with diabetes.
When to Call Your Care Team
Call 911 or go to the emergency room right away if you have trouble breathing. CDC's sick day page also lists these reasons to go to the emergency room: ketones in your urine, being unable to keep liquids down for more than 4 hours, vomiting or severe diarrhea for more than 6 hours, a temperature over 101°F for 24 hours, or blood sugar below 60 mg/dL.
Call the same day for a fever, a cough that is getting worse, a wound that is red, swollen, or draining, burning with urination, or blood sugar readings that stay well above your targets.
At your next visit, ask which vaccines you are due for and whether any recent infections mean your plan should change.
Frequently Asked Questions
Does diabetes weaken the immune system?
CDC says it can. High blood sugar adds stress to the body and makes immune cells work harder, so the immune system might be weakened and less effective. CDC says this can mean getting sick more often, staying sick longer, or getting severely sick. Keeping blood sugar in your target range helps.
Are diabetics more prone to infections?
CDC says research shows people with diabetes can have more frequent respiratory infections, flu, pneumonia, urinary tract infections, and skin infections. CDC also says they might not be more likely to get COVID-19 or flu, but are more likely to become severely ill, especially if blood sugar is not well managed.
Does high blood sugar make it harder to fight infection?
ADA says high blood glucose can make it harder for the body to fight infections. A 2021 research review says chronic high blood sugar is a key cause of altered neutrophil function, and that some germ-fighting jobs of these white blood cells are reduced in diabetes.
Can an infection raise my blood sugar?
Yes. CDC says that when you are sick, your immune system releases hormones that can raise your blood sugar temporarily, and some cold and flu medicines can also raise it. CDC says fever, sweating, and poor appetite can cause low blood sugar, so check more often and follow your sick day plan.
Is the immune system different in type 1 and type 2 diabetes?
CDC says type 1 diabetes is an autoimmune disorder, so people with type 1 may have weaker immune systems. A 2021 review says chronic high blood sugar affects white blood cell function in both type 1 and type 2 diabetes. Your care team can explain what applies to you.
What can I do to support my immune system with diabetes?
CDC lists keeping blood sugar in your target range, eating plenty of fruits and vegetables, being physically active, washing your hands, managing stress, getting enough sleep, and staying up to date on vaccines. CDC says to talk to your doctor before taking vitamin or mineral supplements.
References
- Centers for Disease Control and Prevention. “Your Immune System and Diabetes.” Accessed October 2026.
- Centers for Disease Control and Prevention. “Managing Sick Days.” Accessed October 2026.
- Centers for Disease Control and Prevention. “Flu and People with Diabetes.” Accessed October 2026.
- Centers for Disease Control and Prevention. “Diabetes and Adult Vaccines.” Fact sheet, March 2020. Accessed October 2026.
- American Diabetes Association. “Vaccinations.” Accessed October 2026.
- Dowey R, Iqbal A, Heller S, Sabroe I, Prince L. “A Bittersweet Response to Infection in Diabetes; Targeting Neutrophils to Modify Inflammation and Improve Host Immunity.” Frontiers in Immunology. 2021;12:678771. Accessed October 2026.
- Daryabor G, Atashzar M, Kabelitz D, Meri S, Kalantar K. “The Effects of Type 2 Diabetes Mellitus on Organ Metabolism and the Immune System.” Frontiers in Immunology. 2020;11:1582. Accessed October 2026.
- Al-Sayyar A, Hulme K, Thibaut R, et al. “Respiratory Tract Infections in Diabetes – Lessons From Tuberculosis and Influenza to Guide Understanding of COVID-19 Severity.” Frontiers in Endocrinology. 2022;13:919223. Accessed October 2026.
Next Steps
Pick one habit from the list above to work on this week, and ask your doctor or pharmacist which vaccines you are due for. For a plan built around vaccines, see our vaccine guide for people with diabetes.
For adults with type 2 diabetes or prediabetes who want lifestyle education alongside clinical care, the Done With Diabetes™ program, built around lifestyle changes for type 2 diabetes, organizes learning about meals, movement, sleep, and stress. It does not diagnose or treat diabetes or infections, advise on vaccines, interpret test results, change medicines, or replace your care team.