An acute disease almost always raises blood glucose (sugar) levels because of:

  • the secretion of stress hormones (also known as counterregulatory hormones: primarily cortisol, adrenaline and glucagon), which have an insulin-antagonistic effect;
  • less regular exercise, which makes the injected insulin less effective, even if the amount of food consumed is reduced.

Sick days on insulin

The daily insulin needs of people with diabetes often rise when they get sick. Consequently, even though diabetics may eat less when ill, they still need to take their regular insulin doses as prescribed, or adjusted, by their doctors.

Advice and adjustments

  • Take your blood glucose (sugar) readings more often: every 2-4 hours, or more often if necessary.
  • Take your insulin or diabetes medication as usual, unless advised otherwise by your doctor.
  • Take your temperature: if needed, take acetaminophen to lower your temperature and prevent dehydration through sweating caused by fever.
  • If you have type 1 diabetes: if your blood glucose (sugar) is above 14.0 mmol/L, measure the ketones in your blood or urine every 2 to 4 hours, or more often if necessary.


If you lose your appetite, drink liquid or semi-liquid sources of carbohydrates (fruit sauces, yogurt, etc.) at the rate of 15 g of carbohydrates per hour if you have taken the proper insulin doses.


If your blood glucose (sugar) level is high:

Drink lots of unsweetened liquids (sparkling water, diet soft drinks, bouillon, etc.) to avoid becoming dehydrated, at the rate of 250 ml every hour.

If your blood glucose (sugar) levels tend to fall:

Have small amounts at a time of sweetened foods (fruit juice, regular Jell-OTM, milk, etc.).

See a doctor or go to Emergency if:

  • Your blood sugar is higher than 20 mmol/L with the presence of ketones (moderate to high) — type 1 diabetes
  • Your blood sugar is higher than 25 mmol/L and you feel excessively drowsy — type 2 diabetes
  • You are vomiting continuously and are not able to keep liquids down
  • Your fever stays above 38.5 ºC (101.3 ºF) for more than 48 hours

How to look after yourself

Talk to a pharmacist before using over-the-counter remedies to treat an illness. Make sure that there are no contraindications for people with diabetes.

Cough medicines, expectorants and acetaminophen have no effect on blood glucose (sugar) levels. To ease your cold or flu symptoms, get plenty of rest and stay hydrated. Choose sugarless cough drops to soothe a sore throat, and use saline solution for a blocked nose. It is better for a person with diabetes to regularly use a nasal saline solution instead of decongestants because they affect blood glucose (sugar) levels.

Is it a cold or flu?

A cold is a benign viral infection that generally lasts fewer than 10 days, whereas the flu is a more serious condition, accompanied by high fever (39 °C to 40 °C for 3 to 4 days), headache, muscular aches and pains, chest pain, a dry cough, and exhaustion that can last 2 to 3 weeks.

By lowering the body’s resistance to other infections, the flu can lead to serious, sometimes fatal complications (for example: pneumonia). That is why it is so important for a person with diabetes to talk to his doctor about getting an annual flu shot.

Research and writing: Diabetes Québec team of health care professionals

June 2014