⚠️ CGM lag and low-range accuracy: what to know
⚠️ CGM lag and low-range accuracy: what to know
A clinical education video featuring diabetes specialist nurse Malcolm reviews how continuous glucose monitors (CGMs) work in Type 1 diabetes and underscores a key practice point: CGMs measure interstitial, not blood, glucose, so readings can lag behind blood glucose changes and be less accurate at low ranges. The course also highlights practical gains including real-time trend data, alarms, and data-sharing features that can improve glycaemic management while requiring clinicians to counsel patients on device limitations.
Why It Matters To Your Practice
CGM data can support more informed insulin adjustment and day-to-day diabetes management.
Because sensors sample interstitial fluid, values may not match capillary glucose during rapid rises or falls.
Low-glucose readings deserve extra caution, especially when symptoms and sensor values do not align.
Patient education should include what CGMs can and cannot reliably tell them in real time.
Clinical Benefits
Real-time glucose visibility can help improve glycaemic control.
Trend arrows and alerts may help reduce hypoglycaemia risk.
Shared data can support remote review and collaborative care planning.
Metrics such as time in range and glycaemic variation can help tailor individualized management plans.
Managing Risks
Advise patients to confirm suspected hypoglycaemia with fingerstick testing when recommended by the device or when clinical symptoms do not match the reading.
Discuss lag time during exercise, meals, or correction dosing, when glucose may be changing quickly.
Assess whether the patient has the vision, manual dexterity, and technical comfort needed to use the device safely.
Review alarm fatigue, sensor wear issues, and other barriers that may affect adherence.
The Bottom Line
CGMs are valuable tools for Type 1 diabetes care, but they are not direct blood glucose measurements.
For NPs and PAs, the clinical win is pairing CGM insights with patient symptoms, confirmatory testing when needed, and individualized education.