Hyperglycaemia (high blood glucose levels) occurs more frequently during illness. This is because the body’s defence mechanism for fighting illness puts more glucose into the blood and prevents your insulin from working properly. This will often cause symptoms like passing more urine and feeling thirsty.

When you have diabetes and are feeling ill, there are certain steps that you must follow to try to avoid your diabetes getting out of control or needing hospital treatment.

Conditions that may upset your blood glucose levels include:

  • The common cold or flu
  • Diarrhoea and vomiting
  • Urine or chest infections
  • Leg or foot ulcers
  • Any infection such as tooth abscesses or boils

Have information to help you manage your diabetes during illness to hand.

Test your blood glucose levels more often, at least four times a day, before meals, or more if necessary.

Remember when you are ill:

  • Drink plenty of sugar free fluids, at least three to four litres through the day, as illness and high blood glucose levels can cause dehydration.
  • Continue to take your insulin/medication, you may even require more whilst ill.
  • If you cannot tolerate any food, replace meals with carbohydrate containing drinks, e.g. milk, Complan, soup etc.
  • If these cannot be tolerated take sugary drinks to replace meals e.g. Lucozade, normal coke, pure orange juice etc.
  • Contact your family doctor (GP) if you are vomiting for more than a few hours.
  • Check your urine for ketones if your blood glucose level is above 15mmol/l.

Discuss any over the counter medicines with your local pharmacist.

  • See your family doctor (GP) if an infection is suspected.
  • Contact a health professional if you are unsure about what to do if you are unwell.

If you take insulin and your blood glucose levels are over 15mmol/l or you are vomiting test your urine for ketones. The presence of both high blood glucose levels and ketones in the urine indicates a lack of insulin in your body.

If you take insulin you should always have ketone strips at home. Check regularly to ensure they are not out of date (see patient information leaflet PIF 671 What are Ketones?). 

Risks, benefits and alternatives

Never stop your insulin or diabetes tablets when you are ill, if you do you run the risk of worsening blood glucose levels. Your blood glucose level can rise when you are ill, even if you are not eating. Generally you will need to increase your insulin or diabetes tablets when you are unwell. 

The benefits of monitoring blood glucose more closely whilst ill and adjusting your insulin and tablet therapy during illness will be that symptoms of high or low blood glucose levels will be less severe and treated promptly helping you feel better and reducing the risks of developing dehydration or problems such as diabetes ketoacidosis or hyperosmolar hyperglycaemic state. Speak to your family doctor (GP), practice nurse or diabetes specialist nurse about dose adjustments.


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Further information

NHS 111
Tel: 111

Diabetes UK
10 Parkway
Website www.diabetes.org.uk  

The North West Diabetes UK 
First floor 
The Boultings
Winwick Street
WA2 7TT.
Tel: 01925 653 281
Email: n.west@diabetes.org.uk