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Handling Diabetes When You're Sick

For people with diabetes, being sick can affect blood sugar levels. The good news is that taking a few precautions can help you keep your blood sugar levels under control.

How Does Illness Affect Blood Sugar Levels?

When you get sick — whether it's a minor illness like a cold or a bigger problem — the body sees the illness as stress. To deal with the stress, it releases hormones that increase sugar in the blood.

In one way, this is good because it helps supply the extra fuel the body needs. But in a person with diabetes, it can lead to blood sugar levels that are too high. Some illnesses cause the opposite problem. If you don't feel like eating or have nausea or vomiting, and you're taking the same amount of insulin you normally do, your blood sugar levels can get too low.

Blood sugar levels can be very unpredictable when you're sick. Because you can't be sure how the illness will affect them, it's important to check blood sugar levels often on sick days and change your insulin doses as needed.

Planning for Sick Days

Your diabetes management plan will help you know what to do when you're sick. The plan might tell you:

  • how to check your blood glucose levels and ketones when you're sick
  • which medicines are OK to take
  • what changes you might make to your food and drink and diabetes medicines
  • when to call your doctor

Also, people with diabetes should get the pneumococcal vaccine, which protects against some serious infections. You also should get a flu vaccine every year. These vaccines may help cut down the number of sick days you have and keep your diabetes under better control.

What to Do When You're Sick

Your doctor will give you specific advice when you're sick. But here are some general guidelines:

  • Stay on track. Unless your doctor tells you to make a change, keep taking the same diabetes medicines. You need to keep taking insulin when you're sick, even if you're not eating as much as you usually do. That's because your liver makes glucose and releases it into your blood — even when you're stuck on the couch — so you always need insulin. Some people with diabetes need more insulin than usual on sick days. Even some people with type 2 diabetes who don't usually take insulin may need some on sick days.
  • Check blood sugar and ketone levels often. Your doctor will tell you how often to check your blood sugar and ketone levels — usually you'll need to check more often while you're sick.
  • Pay special attention to nausea and vomiting. People with diabetes sometimes catch a bug that causes nausea or vomiting. But nausea and vomiting are also symptoms of ketoacidosis. If you feel sick to your stomach or are throwing up, it's important to keep a close eye on your blood glucose and ketone levels and get medical help according to the guidelines in your diabetes management plan. The best approach is to stick to your insulin schedule, check ketones regularly, and follow your doctor's advice about when to get help.
  • Prevent dehydration. Be sure to drink plenty of fluids, even if you have nausea or vomiting. Your doctor can recommend the types and amounts of fluids to drink that can help you manage both your illness and your blood sugar levels.
  • Use over-the-counter (OTC) medicines wisely. People sometimes take OTC medicines (the kind you can buy without a prescription) for illnesses like the cold or flu. But these have ingredients that can raise or lower blood sugar or cause symptoms that look like high or low blood sugar. Follow your doctor's advice about taking an OTC medicine. Your doctor might even include common medicines that are OK for you in your diabetes management plan, and can also explain what to check for on medicine labels.
  • Take notes. Your doctor might have a lot of questions about your illness and your symptoms. So it can help if you write down your symptoms, medicines and doses, what food and drinks you had, and whether you kept the food down. Also, tell the doctor if you've lost weight or had a fever, and have your blood sugar and ketone level test results handy.
  • Get some rest. People need rest when they're sick. It helps your body focus its energy on fighting illness. If you think you need to, let a parent take over managing your diabetes for a day or two. Your mom or dad can keep track of your blood sugar levels and figure out the best insulin dosage — and you can get some sleep!

When Should I Call the Doctor?

Your diabetes management plan will explain when you may need medical help and what to do. Here are some general reasons to call your doctor:

  • if you have no appetite or you can't eat or drink
  • if your blood sugar level is low because you haven't been eating much — but remember to take steps at home to bring your blood sugar back up
  • if you keep vomiting or having diarrhea
  • if your blood sugar levels are high for several checks or don't decrease when you take extra insulin
  • if you have moderate or large amounts of ketones in the urine (or high levels of blood ketones if you have a meter that tests for this)
  • if you think you might have ketoacidosis
  • if you can't eat or drink because you're having a medical test like an X-ray, surgery, or a dental procedure

Any time you have questions or concerns, ask your doctor for advice.

Reviewed by: Larissa Hirsch, MD
Date reviewed: September 2019