Sick-day rules: managing diabetes when you're unwell

What to do with diabetes when you have the flu, a stomach bug or another illness: keep drinking, keep checking, keep taking insulin, ask about pausing certain medicines (SADMANS), and check ketones.

6 min read · last reviewed October 3, 2026

Everyone gets sick sometimes: a cold, the flu, a stomach bug, an infection. When you have diabetes, being sick needs a little extra care. Illness and stress hormones can push your blood sugar up, even if you're eating less. Throwing up and diarrhea can dry you out (dehydration), which can strain your kidneys. And if you're not eating, some medicines can make your blood sugar drop too low.

The good news is that a simple plan, made ahead of time, keeps most sick days safe. These are often called "sick-day rules."

Something you can do this week: Ask your team, "Can we make my sick-day plan together?" Write it down and keep it with your medicines.

Rule 1: Keep drinking

Sip fluids often, about a cup (250 mL) every hour while you're awake, unless your team has told you to limit fluids.

• If your blood sugar is high, choose sugar-free drinks such as water, broth or diet ginger ale.
• If you can't eat and your blood sugar is normal or low, choose drinks with some sugar, such as juice or regular pop, to keep your sugar up.

Rule 2: Keep checking

Check your blood sugar more often than usual, for example every 2 to 4 hours, including during the night if your team suggests it. Write down your readings, what you drank and ate, and your medicines. This helps your team give you advice if you call.

Rule 3: Keep eating if you can

Try to eat small amounts of your usual foods. If you can't, try easy-to-digest foods or drinks with carbohydrate, such as crackers, toast, soup, applesauce, popsicles, or juice. This helps prevent lows and gives your body energy.

Rule 4: Don't stop your insulin

If you take insulin, keep taking it, even if you can't eat. Your body still needs insulin when you're sick, and often needs more. Stopping insulin can lead to a dangerous condition called diabetic ketoacidosis (DKA). Your team may tell you how to adjust your doses while you're sick. If you aren't sure what to do, call them.

Rule 5: Ask about pausing certain medicines (SADMANS)

If you're throwing up, have diarrhea, or can't drink enough fluids, some common medicines may need a short pause until you're eating and drinking normally again, usually within 24 to 48 hours. These medicines can cause kidney problems, low blood sugar or other side effects when you're dehydrated.

Diabetes Canada uses the word SADMANS to help you remember them:

• Sulfonylureas (diabetes pills such as gliclazide or glyburide, which can cause lows when you're not eating)
• ACE inhibitors (blood pressure and heart medicines whose names often end in "-pril")
• Diuretics ("water pills") and direct renin inhibitors
• Metformin
• ARBs (blood pressure medicines whose names often end in "-sartan")
• NSAIDs (anti-inflammatory pain medicines, such as ibuprofen and naproxen, found in many cold and pain products)
• SGLT2 inhibitors (diabetes medicines whose names end in "-gliflozin")

Important: Don't stop or change any medicine on your own. Ask your team or pharmacist ahead of time which of your medicines are on this list, and what to do with each one when you're sick. Restart them when you're eating and drinking normally, unless you're told otherwise. Some people may also be told to pause other medicines, such as GLP-1 medicines, if they're throwing up.

Something you can do today: Ask your pharmacist to mark which of your medicines are "sick-day medicines."

Rule 6: Check for ketones, if your team advises

Ketones are acids your body makes when it doesn't have enough insulin to use sugar for energy and starts to burn fat instead. High ketones can lead to DKA.

Your team may ask you to check ketones if you have type 1 diabetes, take an SGLT2 inhibitor, or your blood sugar stays high. Diabetes Canada suggests checking ketones if your blood sugar stays above 14 mmol/L (about 250 mg/dL) before meals for more than a few meals. You can test with blood ketone strips (preferred) or urine strips.

As a general guide for blood ketones:

• Below 0.6 mmol/L: normal.
• 0.6 to 1.5 mmol/L: a bit high. Follow your sick-day plan and re-check in a couple of hours.
• 1.5 to 2.9 mmol/L: high. You are at risk of DKA. Call your team now.
• 3.0 mmol/L or higher: very high. Go to the emergency department or call 9-1-1.

People taking SGLT2 inhibitors can develop DKA even when their blood sugar isn't very high. If you take one and feel unwell, check ketones if you can, and get help.

Call 9-1-1 or go to emergency if you have

• throwing up and can't keep fluids down
• stomach pain, fruity-smelling breath, or deep, fast breathing
• high ketones (3.0 mmol/L or higher in the blood) or ketones with throwing up
• confusion, extreme sleepiness, or feeling very weak
• very high blood sugar with extreme thirst and signs of dehydration (this could be hyperosmolar hyperglycemic state, or HHS, which is more common in type 2 diabetes)
• a severe low that you can't treat yourself

Call your team the same day if

• you've been throwing up or had diarrhea for more than a few hours
• your blood sugar stays above your target, or above 14 mmol/L, for more than a few readings
• your ketones are moderate or high
• you've had repeated lows
• you're not sure what to do with your medicines

Your sick-day kit

Keep these together in one place:

• your written sick-day plan and team phone numbers
• your meter, strips and ketone strips (check the expiry dates)
• a thermometer
• sugar-free drinks, plus juice or regular pop and glucose tablets for lows
• easy foods such as crackers, soup and applesauce

Questions to ask your care team

• Can we write my sick-day plan together?
• Which of my medicines should I pause if I can't eat or drink? When do I restart them?
• How should I adjust my insulin when I'm sick?
• Should I check ketones? Which kind of strips should I use?
• When should I call you, and when should I go to emergency?

This article is general information, not medical advice. Talk with your health care team about your own situation. In an emergency, call 9-1-1 or your local emergency number.

In an emergency, call 9-1-1 or your local emergency number.

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

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