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What to do when you're sick

You are not likely to get sick more often just because you have type 1 diabetes.

But if you do get sick, it can make your blood glucose and ketones higher. This means you should take extra care.

Contact your diabetes team for advice if you're not sure about what to do.

Sick day advice for adults with type 1 diabetes (PDF, 677 KB, 9 pages)

Urgent advice: Contact your diabetes team if:


  • keep taking your insulin - you may need more than usual

  • check your glucose levels more often than normal - every 2 to 4 hours

  • check the insulin adjustment table in the Sick day advice booklet or ask your diabetes team if you're not sure

  • drink lots of water or sugar-free drinks to avoid dehydration

  • try to eat small amounts regularly

  • check for ketones - you can get blood ketone test strips on prescription from your pharmacy and a ketone meter from your diabetes team

If you cannot eat, drink carbohydrate drinks like milk, full-sugar soft drinks or fruit juice, or have ice cream or sweets.


  • do not worry about taking medicines that contain sugar, for example over-the-counter cough medicine. Small amounts of sugar won't cause problems.

  • do not fast - try to eat normally if you can

  • do not stop taking your long-acting insulin, even if you are unable to eat.

Glucose levels and ketones

For most people it is normal to have blood glucose between 4 to 12mmol/l when they are sick.

Vomiting or diarrhoea may make your blood glucose levels go too low.

Treat a hypo

If your blood glucose levels go too high, you may need more insulin than normal. Ask your diabetes team if you are unsure.

When you are unwell, high levels of ketones in your blood can develop and lead to diabetic ketoacidosis (DKA). This can be life-threatening.

Make sure you have a meter and strips for testing for ketones in your blood. You can get blood ketone test strips on prescription from your pharmacy and a ketone meter from your diabetes team.

Sick day advice for adults with type 1 diabetes (PDF, 677 KB, 9 pages)

Emergency action required: Contact your diabetes team, or go to the emergency department or phone 999 immediately if

your glucose level is high and you have symptoms of DKA:

  • ketone levels over 3mmol/l
  • abdominal pain
  • fast breathing
  • feeling or being sick
  • your breath smells of pear drops or acetone
  • a sweet or metallic taste in your mouth

You will need treatment in hospital.

Going to hospital

Tell staff as soon as you arrive that you have type 1 diabetes. Tell them if you use a glucose sensor or an insulin pump.

Tell anyone who is treating you that you have type 1 diabetes.

It's important for you to continue to get your insulin and to have food containing carbohydrates. You can discuss this with the team looking after you.

If you cannot eat or drink because you need a test or an operation, you might need a glucose drip.


Keep up to date with your vaccines - including flu, pneumococcal and COVID-19.

Your GP will advise you about any that you need.

Everyone with type 1 diabetes can get the flu vaccine for free.

Page last reviewed: 17 October 2023
Next review due: 17 October 2026

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 9.