Why the flu is different for people with diabetes

The flu is a respiratory infection caused by an influenza virus. Common symptoms include fever, chills, muscle aches, sore throat, cough, and congestion. These viruses spread year-round, but the number of cases typically increases significantly in the fall and winter months, a time of year referred to as “flu season.”

The severity of flu illness varies from person to person. Some people experience only mild symptoms and recover within a few days. Others experience more severe symptoms and are sick for a week or longer. And some people become severely ill, experience life-threatening complications, and require hospitalization.

While the flu can be unpredictable, certain factors put a person at greater risk of severe illness and complications. One risk factor is having an existing chronic health condition. A chronic health condition commonly associated with severe flu illness and complications is diabetes.

Understanding diabetes

Diabetes is a group of chronic health conditions that cause high levels of blood glucose. Blood glucose, commonly called blood sugar, is the body’s major source of energy. Nearly all cells in the body rely on glucose in order to function normally and remain healthy.

Essential to this process is a hormone called insulin, which guides glucose from the bloodstream into cells. For a simple illustration, think of insulin as a key that opens a cell to let glucose inside.

When a person has diabetes, the body does not produce enough insulin and/or is unable to use insulin. As a result, blood glucose cannot effectively move into cells and instead remains in the bloodstream.

Blood glucose levels that are too high for too long can damage blood vessels and nerves, leading to many different complications. These complications include cardiovascular disease, vision loss, kidney disease, stroke, nerve damage, and many others. The risk of these complications exists even when diabetes is well managed.

Different types of diabetes have different causes:

• Type 1 diabetes is an autoimmune disease. It occurs when the body’s immune system attacks and destroys the cells that produce insulin.
• Type 2 diabetes accounts for approximately 90 percent of diabetes cases. Risk factors include overweight/obesity, being physically inactive, and family history.
• Gestational diabetes occurs during pregnancy. It is caused by changes in hormone levels and body composition that occur during pregnancy. Gestational diabetes increases the risk of other health problems during pregnancy, problems with fetal development, and having type 2 diabetes in the future.

Diabetes and the risk of severe illness

Diabetes weakens the immune system, the body’s defense against illness and infection. This makes a person who has diabetes more likely to become infected with the flu, more likely to experience severe illness, more likely to experience flu-related complications, and more likely to be hospitalized. According to the Centers for Disease Control and Prevention, roughly 30 percent of adults who are hospitalized for the flu have diabetes.

Flu-related complications among people with diabetes:

• Uncontrolled blood glucose, including elevated blood glucose levels and episodes of hypoglycemia (very low blood glucose).
• Secondary bacterial infections, including sinus infections, ear infections, bronchitis, and pneumonia—a serious lung infection that can lead to respiratory failure and other complications.
• Heart attack or stroke. Cardiovascular disease is the leading cause of death among people with diabetes, and flu illness significantly increases a person’s risk of having a heart attack or stroke.
• Sepsis, an extreme overreaction to an infection by the body’s immune system, which can cause organ failure and death.

Not everyone who has diabetes will experience severe illness or complications from the flu—and studies show that getting an annual flu shot can protect against these types of outcomes. People who are vaccinated against the flu are less likely to get sick and less likely to experience severe illness or complications if they do get sick.

Your best source of information on flu vaccines—and which flu vaccine you should get—will be your healthcare provider and/or pharmacist.