Looking after your diabetes when you are unwell

• It is essential that insulin is working in the body at all the times. You can never stop insulin. 
• Insulin doses may need to be changed when you are unwell. 
• Monitoring of glucose and ketones will increase.
  
• Always check ketone levels when you are unwell, regardless of what the glucose level is.
  • Whilst unwell, ketones should be checked every 4 hours, however, if they rise to 1.0 mmol/L or higher, they need to be more closely monitored every 2 hours. The advice on this page explains how to manage ketones depending on the blood glucose level (BGL).
• If vomiting and ketones are present and you are unsure of appropriate treatment, call your diabetes treating team early for support with insulin dose adjustments.
• Check your fingerprick BGLs when unwell, do not rely on continuous glucose monitor (CGM) for your glucose readings.  

Sick day management falls broadly into two different categories:

1. Illnesses that cause Hyperglycaemia (High BGL’s)

• Illness can trigger stress hormones that cause insulin resistance. This can lead to high BGLs.
  
• Insulin doses may need to be adjusted and increased when managing these types of illnesses. 
  • Making insulin dose adjustments 
    
  • Correcting high glucose levels when ketones are less than 1.0 mmol/L 
    
• Check BGL’s every 2 hours.
• Check blood ketones every 4 hours, if ketones are 1.0 mmol/L or higher, see the information below. 
• See your GP to treat underlying the illness / infection.
• Some acute illnesses (asthma, croup etc) may be treated with steroid medication such as hydrocortisone, prednisolone or dexamethasone. Steroids such as these may cause high BGLs. 
  
• Give pain relief to relieve headaches or sore throat. 
• Encourage sugar free fluids to maintain hydration.

2. Illnesses that cause Hypoglycaemia (Low BGL’s)

• Vomiting, diarrhoea, nausea and reduced appetite can all lead to Hypoglycaemia.
• Check BGL’s every hour.
• Check blood ketones every 4 hours. Ketones can be produced during illness even with normal or low BGL’
• Insulin doses may need to be decreased. Remember: Insulin can never be stopped but doses can be reduced to minimise the frequency of hypo with decreased appetite.
  • Never stop long-acting insulin injection (glargine/Ryzodeg®/Levemir®), although the usual dose might need to be reduced.  
  • Rapid acting insulin doses will need to be reduced with reduced appetite. Start by reducing NovoRapid®/Humalog® by 10% -20%. For example, if your usual doses of NovoRapid are 8 units pre meals, you may need to reduce these doses to 6-7 units NovoRapid pre meals and reviewing how this adjusted dose is going.   
• Sip on sugar containing fluids e.g. sips of lemonade or lemonade icy poles or diluted juice. 
  
• Mini doses of glucagon may be used to treat hypoglycaemia if unable to tolerate food or fluids.

What to do if ketones are 1.0 mmol/L or higher

• You’ll need to check BGL 1-2 hourly and ketones 2 hourly until blood ketones are less than 1.0 mmol/L. 
• Use rapid-acting insulin (e.g. NovoRapid®/Humalog®) to treat elevated ketones 
• This is a printable plan to support your ketone management with injections. 
  Ketone Management Plan

If BGL 15mmol/L or higher 

1. Give an 'urgent dose' of rapid acting insulin immediately. This amount is 10% of your total daily insulin (TDD) using NovoRapid®/Humalog®. 

• To do this: Add up all the insulin you usually have over 24 hours (rapid acting + long acting) and divide this by 10 to get 10% of the amount to inject as rapid acting insulin
  e.g. if your doses are; 4 units Novorapid® for each of breakfast, lunch and dinner and 8 units glargine at night. The TDD = 20 units. 10% of this is 20 divided by 10 = 2 units
  - If you are due NovoRapid®/Humalog® i.e. it is a meal time, add this 10% onto your usual meal time dose of NovoRapid®/Humalog®.
  - If it is not a meal time, give 10% of The TDD dose as an extra injection immediately.    

2. Check ketones in 2 hours and seek medical advice if ketones remain 1.0 mmol/L or higher. 

• An additional 10% of rapid acting insulin will be required if if BGL remains 15mmol/L or higher and ketones remain 1.0 mmol/L or higher after 2 hours.  

Seek medical advice if ketones continue to rise.

If your child has vomiting, abdominal pain, rapid breathing, drowsiness or has ketones of 3.0 mmol/L or higher, call an ambulance by dialing 000.

If BGL is between 8.0mmol/L - 14.9mmol/L

1. Give 5 -10% of TDD dose using rapid acting insulin (NovoRapid®/Humalog®).
      - If you are due NovoRapid®/Humalog® i.e. it is a meal time, add the 5-10% amount to your meal time dose.  
      - If it is not a meal time, give 5-10% of the TDD as an extra injection immediately.
       (To calculate the 5% amount: halve the amount you have worked out for 10%) 

• Encourage extra carbohydrate to maintain the BGLs e.g. 6 x crackers or 1 slice of toast. 

2. Check ketones in 2 hours. Another dose of rapid acting insulin may be required if ketones remain 1.0 mmol/L or higher. 

If BGL is between 4.0mmol/L – 7.9mmol/L

• Encourage extra carbohydrate to maintain BGLs e.g. cracker or bread. 
• Give your usual insulin doses with meals.
• Check ketones in 2 hours and seek medical advice if ketones remain 1.0 mmol/L or higher. 

If BGL is 3.9 mmol/L or lower

• Treat hypoglycaemia and encourage sweetened fluids e.g. lemonade icy poles or diluted juice (fluid containing carbohydrates).
• Seek medical advice if insulin is due. A reduction in the insulin doses will likely be needed. 
• Check ketones in 2 hours and seek medical advice if ketones remain 1.0 mmol/L or higher.

Last updated January 2026