Managing Diabetes

Sick Day Rules

Diabetes and illness

Sick day rules - what precautions should I take?Having diabetes does not mean you are likely to fall ill more often than anyone else. However, there are some precautions you should take when you are sick in order to avoid acute complications of diabetes especially if you have type 1 diabetes. Part of the body's natural response to the stress of an illness (such as an infection or injury) is to make more sugar. In people with type 1 diabetes this may lead to very high blood sugar levels and a condition known as diabetic ketoacidosis. (Please refer to the leaflet on ketoacidosis for further information.) During periods of illness you may experience loss of appetite and reduce your intake of food. Many insulin treated patients reduce or stop insulin due to concerns about hypoglycaemia during intercurrent illness. 

What precautions should I take?

  • Never stop taking your insulin or omit doses. Your blood sugar levels may continue to rise even if you do not eat.
  • If your blood sugar levels are higher than 10 mmol/l you may consider taking a larger or additional dose of insulin.
  • Test your blood glucose more often.  If your levels are unstable increase the frequency to every 4 hours or more.
  • If blood glucose readings are higher than 13 mmol/l, and you are unwell or vomiting, check your urine for ketones. Use 'Ketostix' strips to test your urine. Your Diabetes Specialist Nurse or Practice Nurse will advise you on how to obtain these strips. Some blood glucose meters allow you to test for ketones as well (MediSense Optium), and this is quite acceptable. However, testing for ketones in the urine is a very sensitive test and there is no necessity to demonstrate ketones bodies in the blood.
  • Drink lots of fluids. Its easy to become dehydrated when you are ill especially if you have a temperature, vomiting or diarrhoea. If you are unable to keep fluids down call your doctor. You also lose fluids through sweating and breathing. Aim to drink at least 3 litres of fluid a day. If you take this in small amounts such as a glass every hour you should manage to cope with the extra volume. If this is difficult persist with regular sips. When people are admitted to hospital with ketoacidosis they are severely dehydrated and require as much as 6-9 litres of fluids to restore lost volumes.
  • Stick to your normal diet as far as possible. If unable to eat solids take liquids and even sugary drinks if necessary.

I have ketones in the urine

If your blood glucose is continuously more than 17 mmol/l or if you are vomiting, test your urine for ketones. Ketones may appear in the blood and urine due to starvation. They also can indicate a lack of insulin. The presence of ketones in the urine may be a warning of developing ketoacidosis and should be acted upon. Remember ketoacidosis is a life threatening emergency which needs to be identified and treated quickly.

Advice on diet

Try to drink 4-6 pints of sugar-free liquids (water, tea) throughout the day.

If you don't feel like eating, replace your solid food with soup, milk, ice cream, fruit juice, sugar, honey, fruit juice.

Advice on insulin

Follow these general guidelines.

Blood glucose


less than 13 mmol/l

continue with your normal dose of insulin

13 - 22 mmol/l

take 2 units extra of insulin with each injection, even if you are unable to eat anything

greater than 22 mmol/l

take 4 extra units of insulin, even if you are not able to eat

Reduce your dose of insulin back to your usual dose when blood glucose returns to normal.

Know when to call for help!

You or a member of your household should seek assistance in the event of any of the following. Speak to your Specialist Nurse or your GP. If in doubt always seek advice - it is better not to leave it too late!

  • Unable to eat or drink
  • Loss of fluids due to repeated vomiting or diarrhoea
  • Very high blood sugar levels (higher than 25 mmol/l) despite taking more insulin
  • persistent ketones or 'large' ketones
  • blood glucose levels are low
  • if you become drowsy or confused
  • if you are worried!


Dr Nishan Wijenaike, Consultant Physician
West Suffolk Hospitals Diabetes Service
Revised June 2005