Should I Get a Flu Shot if I Have Diabetes?

Having type 1 or type 2 diabetes puts you at increased risk of illness because elevated blood sugar weakens the immune system. Getting an annual flu shot is the best way to protect yourself.

Flu shots are recommended for people with diabetesIt's flu shot time. The CDC urges people with diabetes to receive the influenza vaccine every year.

Fall is here, and that means that along with pumpkins and hay rides, it’s influenza (flu) season—which can last until May.

For those with diabetes, flu isn’t just a drag: It can result in hospitalization, and occasionally even death.  Fortunately, a vaccine can slash your risk of the illness by an estimated 40-60%, according to the Centers for Disease Control and Prevention (CDC).  The flu shot also lowers your chances of hospitalization,  which is most common in flu patients with chronic conditions like diabetes.

The vaccine can also “prevent major respiratory infections during the flu season,” says Kavita Seetharaman, MD, staff physician at Joslin Diabetes Center, a Boston-based non-profit affiliated with Harvard Medical School.

Why Is the Flu So Dangerous for People with Diabetes?

“As with any other infection, the flu virus can cause inflammation, congestion, and mucus production in the respiratory tract,” as well as cough, fever, and even breathing difficulties, Dr. Seetharaman says.

But for diabetes patients, there’s another risk. “When patients with diabetes are not feeling well,” due to illness, infection, or injury,  “they can become more insulin resistant. Blood sugar rises [even if patients aren’t eating], and ketones can develop,” she explains. Ketones are chemicals that are produced when there’s not enough glucose (sugar) to fuel the metabolism; the presence of ketones (which can be detected with over-the-counter test strips) indicate that the body is using fat for energy.

Patients with diabetes can accumulate ketones in the blood, which can make them very sick. Patients with both high ketones and persistently high blood sugar levels (usually above 250 mg/dL) who don’t respond to blood sugar corrections are at risk of diabetic ketoacidosis (DKA), a potentially life-threatening illness that requires hospitalization. DKA is most common in people with type 1.

For people with type 2, dehydration and high blood sugar can lead to Hyperosmolar Hyperglycemic Nonketotic Syndrome (HHNS). This condition, in which blood sugar levels may increase to over 600 mg/dL, can cause excess sugar to pass into the urine, leading to frequent urination. Dark urine, confusion, extreme thirst, a parched mouth, loss of vision and hallucinations are other warning signs.

"For type 2s who are on insulin, a dose adjustment may be necessary and patients with symptoms of dizziness, nausea and vomiting and diarrhea will benefit from IV fluids, " Dr. Seetharaman explains. "If they are sick with diarrhea and vomiting, they may need to hold off on taking some of the oral medications for diabetes until they feel better. I recommend a close follow up with their primary care physician and diabetes team to assist in recovering from the flu."

Staying well hydrated is extremely important, as severe dehydration can lead to seizures, coma, and even death.

Flu Transmission and Symptoms

Influenza, or the flu, is a notoriously contagious viral infection that in addition to making you feel achy and fatigued, also impacts the respiratory tract—the nose, throat, and lungs. Flu patients can pass it to others through droplets of expectorated mucus when coughing, sneezing or talking. Healthy people can pick up the flu by touching contaminated surfaces (cell phones, countertops, the refrigerator handle) and then touching their faces. So frequent hand washing is advised during flu season.

Symptoms of the flu include:

  • Fever/chills
  • Cough
  • Sore throat
  • Runny nose
  • Body aches
  • Headaches
  • Fatigue
  • Flushed skin
  • Vomiting and diarrhea

Complications of the flu can cause pneumonia, ear infections, sinus infections, bronchitis, dehydration and the worsening of chronic conditions. Dangerously low blood sugar or DKA in people with type 1, and dangerously high blood sugars or HHNS, more common in people with type 2, are other complications.

If you suspect you’ve contracted the flu, “Call your doctors and update them—we really want to prevent ketoacidosis,” Dr. Seetharaman urges. And if you do have the flu, “follow sick day guidelines:  check blood sugars with a finger stick and correct high blood sugars with insulin every four hours, even if you’re not eating.” In addition, “stay well hydrated to help prevent ketoacidosis.”

She adds that patients should treat symptoms as advised by their medical team. Patients should also keep in mind that acetaminophen (the pain reliever/fever reducer ingredient in Tylenol and other medications) can alter the accuracy of a continuous glucose monitor reading. So, if you’re taking the medication, use a finger stick to check blood glucose.

For those with severe symptoms, an anti-viral medication (such as Tamiflu) may be an option, particularly if taken within 72 hours of the onset of flu symptoms. “Most patients will improve within 24-48 hours of starting the medication,” Dr. Seetharaman says. They’ll also “have a better chance of recovery without getting worse and needing hospitalization.” (Note: Be mindful of over-the-counter cough and cold medications that may contain sugar.)

If You Do Get Sick…

When freelance writer Ginger Vieira came down with the flu 5 years ago, she followed sick day rules and managed to stay on top of her blood sugars—and out of the hospital. “I did have moderate and large ketone measurements the first few days,” recalls the author of Emotional Eating with Diabetes, Pregnancy With Type 1 Diabetes, and Dealing With Diabetes Burnout, who was diagnosed with T1D in 1999 and also has celiac disease.

After speaking with her certified diabetes educator (CDE), Vieira increased her basal insulin dose by 20%, even though she had no appetite and wasn’t eating much. “This kept my blood sugar in range and my ketones at a minimum. Without this increase, my blood sugars were sitting well above 200 mg/dL.”

In addition, “I also drank Gatorade in order to get some carbohydrates, not only to give my body fuel while it battled the flu but also to prevent … [more] ketones.” 

Flu patients can also benefit from the vaccine. The shot “can prevent other forms of the flu,” Dr. Seetharaman observes. “Get the shot once you’re feeling completely well, in 2 to 3 weeks.” She adds that for 2017-2018, the CDC recommends the injectible vaccine only.  Flu shots take about two weeks to become effective.

Since her bout with the flu, Vieira has made sure to get the vaccine annually, and, she adds, “I have not actually gotten the flu since!”


Updated on: September 12, 2018
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