First published September 23, 2024

Updated on September 17, 2026

Just like many chronic illnesses, type 1 diabetes (T1D) can “open the door” to viruses and bacteria, especially when blood sugar levels are high over a long period. 

Depending on age and blood sugar management, someone with T1D is up to four times more likely to be hospitalized with an infection than the general population. And although modest, the risk of death is also higher for people with T1D.

Vaccines help fight against infections, especially viruses. Diabetes specialists’ associations and public health authorities therefore recommend that people with T1D follow their province’s vaccination schedule for the general population and receive a few additional vaccines as well, which are often offered free of charge to people with diabetes. 

However, please consult with your healthcare team before you make an appointment. While vaccines are safe and reliable for people with T1D, some are not indicated if you have allergies or a weakened immune system (e.g., if you take medications that weaken the immune system, such as treatments for certain cancers or forms of arthritis, or following an organ transplant). 

The vicious circle of T1D and microbes

If blood sugar regularly remains above 10.0 mmol/L on a daily basis, the immune system may be weakened, making one more vulnerable to viruses and bacteria.

During sickness, blood sugar levels may be even higher and even harder to keep within the target range (between 4.0 and 10.0 mmol/L), which will predispose to complications (e.g., pneumonia requiring hospitalization). Infections are stressful for the body, which will release large quantities of glucose into the bloodstream and reduce the effectiveness of insulin. These two phenomena working together is the perfect recipe for hyperglycemia, and it often requires an increase in insulin doses. But, be careful! Having difficulty eating sufficiently, or vomiting may induce hypoglycemia. 

Contracting an infection will cause a blood sugar imbalance, which will ultimately increase the risk of contracting other viruses or bacteria. Hyperglycemia caused by infections often leads to additional medical visits and hospitalization.

To avoid getting caught in this vicious circle, it’s important to maintain good general health, limit tobacco, adopt good hygiene habits (including regular handwashing) and consider vaccination.

Do vaccines carry any risks?

Vaccines are not guaranteed to provide total protection against an illness, but science has clearly established their effectiveness in reducing the risk of contamination and, particularly, the risk of contracting a serious infection. 

Vaccines are associated with unpleasant side effects such as aches, pain at the injection site and fatigue, but these are often minimal and temporary. The risk of serious complications does exist, but it is very, very marginal. 

As the advantages outweigh the disadvantages, vaccination is considered safe and is recommended for everyone, and especially for people with T1D. Vaccines don’t affect blood sugar management (except for possible moderate and temporary hyperglycemia following the injection), whereas infections often result in significant and prolonged hyperglycemia, predisposing to serious complications (e.g., more severe symptoms, hospitalization).

Which vaccines are recommended?

Of all vaccines available, some are specifically recommended for people with diabetes. 

Vaccines and T1DDownload

What about children? 

According to various studies, children and adolescents who live with T1D and manage to keep their blood sugar levels within the target range generally don’t contract more illnesses and infections than those who don’t live with this condition. However, if they get sick, they run a higher risk of complications and hospitalization.

In the event of illness, vaccination, particularly against pneumococcus and influenza, helps to fight microbes and prevent complications and unbalanced blood sugar levels. No additional risk of triggering other autoimmune diseases has been reported in children and adolescents with T1D.

Health authorities recommend that children be vaccinated according to the regular vaccination schedule, with the addition of the annual flu vaccine starting at the age of 6 months.

Encourage vaccination with family and friends

Close ones are a potential source of infectious agents. Therefore, it is recommended that their vaccination records be up to date, including with the seasonal flu vaccine.

In short, immunization through vaccines is preferable to immunization through infection. Unlike microbes, vaccines don’t increase the risk of illness-related complications, and won’t destabilize blood sugar levels.

To learn more, connect and check out our courses on vaccination and sick days.

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Written by:  Nathalie Kinnard, scientific writer and research assistant

Reviewed by:

  • Amélie Roy-Fleming DtP, MSc, CDE
  • Rémi Rabasa-Lhoret, MD, Ph.D.
  • Sarah Haag, R.N., B.Sc.
  • Claude Laforest, Eve Poirier, Jacques Pelletier et Michel Dostie, patient partners of the BETTER project.