Managing High Blood Glucose and Ketones (for Multiple Daily Injections)

Who is this for?

This guide is for children and young people with Type 1 diabetes, and their families, to help manage high blood glucose levels and illness when using multiple daily insulin injections.

✅Understanding Blood Glucose Targets

• Your ideal glucose target range is between 3.6 and 9 mmol/L.
• This target applies whether you're using a finger prick test or a continuous glucose monitor (CGM).
• Aim to stay in this range at least 70% of the time, and try to spend less than 4% of the time below 3.6 mmol/L.

📈When Glucose Is High

• If it’s been more than 2 hours since your last dose of rapid-acting insulin and your levels are still high, you might need an extra injection of insulin.
• Only use rapid-acting insulin (e.g., NovoRapid, Humalog, Apidra, Fiasp or Lyumjev) for correction boluses.

High Glucose + Ketones = Act Fast

• If you have high blood glucose and ketones, it means your body doesn’t have enough insulin.
• You’ll need to increase your insulin dose more than usual.

Using a Bolus Calculator

• We assume you’re using a bolus calculator like the mylife™ app (free on Apple and Google Play).
• If not, use your Insulin Sensitivity Factor (ISF) to calculate your correction dose. Ask the diabetes team if you do not know what this is.

💧Keep drinking fluids

• High blood glucose and ketones can make dehydration worse.
• Drink sugar-free fluids – especially when your blood sugar is above the target range.

Using CGM when unwell

• Some medication may affect accuracy of CGM e.g. paracetamol.
• Dehydration means that the amount of fluid in the body is reduced, this can make sensors less accurate.
• Check a finger prick glucose to confirm sensor accuracy.

📞Need help? Contact us

• Emergency Mobile: 07940 476 811

• Email:

  uclh.cdorange@nhs.net

  uclh.cddietitians@nhs.net

🔗More info

Further information and fact sheets can be found on our Children and Young People’s Diabetes web page.