Capillary blood ketones (CBK) measurement and interpretation 

 At present capillary blood ketone (CBK) testing is only available at: 

• GRI - AAU, HDU and diabetes wards. 
• QEUH - A&E, IAU, ARU2, HDU and diabetes wards. 
• Other hospital sites - please check with your local ward area. 

It should not be used outwith these areas.  

If your area does not have CBK testing, the following conversion between CBK and Urine Ketones can be used: 

• CBK >1.5 - 3mmol/L = Urine Ketones ++
• CBK >3mmol/L = Urine Ketones +++ or ++++

Who do I check blood or urine ketones in? 

Patients with type 1 diabetes or secondary (pancreatic) diabetes. 

When do I check blood or urine ketones?

Capillary blood glucose (CBG) >14mmol/L or unwell. 

What do the results mean?   

CBK <0.6mmol/L - normal. 

CBK 0.6-3mmol/L - requires additional insulin: check venous blood gases (VBG) to exclude diabetic ketoacidosis (DKA) and ongoing CBG and CBK monitoring.

CBK >3mmol/L - significant risk of DKA:  check VBG to exclude DKA and ongoing CBG and CBK monitoring.  Refer to protocol for DKA / hyperglycaemia for details on further management for elevated ketones.

Guideline reviewed: February 2025 

Page updated: November 2025