This personalised insulin calculator has been developed specifically for patients attending a Positron Emission Tomography (PET) department for an 18F-FDG PET/CT scan and who are hyperglycaemic (BGL > 10mmol/L) on arrival. The calculator uses the patient’s weight (kg) and height (cm) as well as their Blood Glucose Level (BGL, in mmol/L) to calculate a recommended dose of intravenous (IV) Actrapid to administer, in order to correct the hyperglycaemia prior to injection.
Once the insulin has been administered, the BGL should be monitored regularly (at least every 15 minutes) to ensure that it has reached a nadir (or low point) and the BGL has definitely started rising again, before the FDG is injected. If there is uncertainty, wait another 15 minutes and check again. If FDG is injected before the insulin effect has worn off (typically 90-120 minutes after IV Actrapid administration) the scan quality may be compromised by increased skeletal muscle uptake under insulin stimulation of GLUT4 transport. It is important to ensure the patient has otherwise prepared appropriately for the scan (ie fasting state).
Should symptomatic hypoglycaemia occur after IV Actrapid administration (a very rare occurrence [<1%] with this personalised insulin calculator), it should be reversed by glucose administration and the scan aborted and rescheduled. Patients at higher risk for hypoglycaemia include those with low weight / body mass index (BMI), type 1 diabetes mellitus, renal impairment.
This calculator has been specifically developed for use in an adult population, and should not be used for paediatric patients.
For information about the clinical use of this tool, refer to paper "Personalised insulin calculator enables safe and effective correction of hyperglycaemia prior to FDG PET/CT" as published in EJNMMI Research.
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