Managing High Glucose Levels and Ketones with Hybrid Closed Loop (HCL) Systems : University College London Hospitals NHS Foundation Trust

This guide is for children and young people with type 1 diabetes, and their families, who use a Hybrid Closed Loop (HCL) system in automated mode, like:

Medtronic 780G
T:Slim with Control IQ
Ypsopump with CamAPS
Omnipod 5

✅Understanding Blood Glucose Targets

Your 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

Your HCL system adjusts automatically by increasing basal insulin
Some HCL systems also give automatic correction boluses
Check that you are using the lowest glucose target (in pump settings)
Remember to change your infusion set/POD at least every 3 days

⚠️Watch for Infusion Set or POD Issues

Most cases of diabetic ketoacidosis (DKA) on HCL happen due to:

Infusion set/POD not working properly
Insulin not absorbing well
If your glucose stays above 14 mmol/L for more than 90 minutes, change the set/POD right away.
If glucose and ketone levels are improving after the first set/POD change a second set/POD change is not required when following the Step-by-step Guide.

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
If ketones >1.5 mmol/L, switch to manual mode and set a temporary basal rate to increase insulin delivery
If ketones >1.5 mmol/L, give correction boluses using an insulin pen
Only use rapid-acting insulin (e.g., NovoRapid, Humalog, Apidra, Fiasp or Lyumjev) for correction boluses.
Follow the ‘step by step’ guide below

💧Keep Drinking Fluids

High glucose + ketones = risk of dehydration
Drink plenty of water or sugar-free fluids, especially if glucose is high

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.