Insulin pump and glucose sensor (CGM)

Two different devices on one patient: a pump that delivers insulin and a sensor that reads glucose. If they are unwell or in DKA, stop the pump and never treat off the sensor alone - confirm on a blood glucose.

Adult & paediatricOtherGuideline

Also called: insulin pump, CSII, continuous subcutaneous insulin infusion, CGM, continuous glucose monitor, Libre, Dexcom, hybrid closed loop, artificial pancreas, sensor

What it is

People with diabetes increasingly wear two separate technologies, and telling them apart is the first task. An insulin pump (CSII) delivers insulin continuously through a small cannula, replacing injections. A continuous glucose monitor (CGM) - a sensor on the arm or abdomen - reads interstitial glucose and displays a trend. A hybrid closed loop links the two so the pump adjusts to the sensor.

The two ED traps follow from this. First, a pump is the patient's only source of insulin: if it stops, or they become too unwell to self-manage, they will run out of insulin and can go into DKA. Second, a sensor reads interstitial glucose and can be wrong when it matters most, so the guidance is clear that CGM can be used to augment capillary glucose testing in hospital but cannot replace it. Pumps and sensors are used across ages, including many children with type 1 diabetes; paediatric dosing and decisions are directed by the paediatric diabetes team.

How to recognise it

An insulin pump: a pager-sized device clipped to clothing or a tubeless 'pod' stuck to the skin, connected by a fine cannula - it delivers insulin.
A CGM sensor: a small round or oval patch, usually on the upper arm or abdomen, that reads glucose - it delivers nothing. The guidance notes that if a patient is unconscious you should check the usual sites - arm, abdomen, or occasionally on thighs or buttocks.
A patient (or child and parent) who manages their diabetes with technology and can usually tell you exactly what each device is and its settings.

What goes wrong

DKA, or the acutely unwell / unconscious patient on a pump

A pump patient who is vomiting, unwell, confused or drowsy, with high glucose and ketones - developing DKA, often fast because the pump uses only rapid-acting insulin with no long-acting depot.

Red flag
Stop relying on the pump. The guidance: an insulin pump should be discontinued if there is any impairment to consciousness, or if the person with diabetes is acutely unwell and/or confused. Treat DKA on the standard pathway - fixed-rate IV insulin in adults; a child under paediatric care follows the BSPED paediatric DKA guideline, which differs - and do not try to run DKA through the pump.

Pump failure / insulin interruption

A blocked or dislodged cannula, an empty reservoir, or a failed pump - rising glucose and ketones because insulin delivery has stopped.

Red flag
A pump patient with no working pump has no insulin. The guidance: if there is disruption of delivery ensure an alternative source of insulin is started immediately (intravenous or subcutaneous injections). Do not wait.

Treating the sensor instead of the blood

A sensor glucose that drives a treatment decision - especially a low reading, or a reading that does not fit the patient - acted on without a confirmatory blood glucose.

Red flag
Interstitial sensor glucose lags and can be inaccurate in acute illness. Always confirm on a capillary (or lab) glucose before treating when symptoms do not match sensor glucose, the reading seems unlikely, or you are following sick-day rules. The gold standard stays laboratory/capillary glucose.

Hypoglycaemia on a pump (over-delivery or bolus stacking)

A pump patient who is sweaty, confused, fitting or unconscious with a low glucose - from too much insulin (stacked boluses, a mis-set basal, or a closed loop overcorrecting) - sometimes with a sensor that is under-reading or lagging the true low.

Red flag
Treat the hypoglycaemia at once (oral carbohydrate, or IM glucagon / IV glucose if they cannot swallow), and suspend or disconnect the pump so it stops delivering while you correct. Confirm on a blood glucose - the sensor can mask or lag a real low - and switch a hybrid closed loop to manual.

The first ten minutes

Identify which device is which - pump (delivers insulin) versus sensor (reads glucose). Check the arm, abdomen, thighs or buttocks in an unconscious patient.
Check a capillary blood glucose and blood ketones - do not act on sensor glucose alone. The guidance: CGM can be used to augment capillary glucose testing in hospital but cannot replace it, and The current gold standard for glucose monitoring and diagnostic purposes remains laboratory blood glucose.
If the patient is in DKA, acutely unwell, confused or has impaired consciousness, stop the pump and start the standard DKA pathway (IV fluids and fixed-rate IV insulin in adults; the BSPED paediatric pathway for a child under paediatric care) - the pump is not the route for a sick patient. When the pump comes off, insulin must go on by another route.
If the pump has failed but the patient is well, remember they still need insulin - give it by another route (subcutaneous or IV) rather than leaving them without.
Label, store and document any device you remove.
Contact the diabetes specialist team - the guidance is explicit that All people using insulin pumps should be discussed with a member of diabetes specialist team (and the paediatric diabetes team for a child).

Do not

Do not treat a glucose decision off the sensor alone.

CGM reads interstitial glucose, lags real blood glucose and can be inaccurate in acute illness. Confirm on a capillary or laboratory glucose before acting - especially when the sensor reading does not match the patient.

Do not try to manage DKA or a seriously unwell patient on their pump.

The guidance says to discontinue the pump when consciousness is impaired or the patient is acutely unwell/confused. DKA is treated with IV fluids and a fixed-rate IV insulin infusion on the standard pathway, not through the pump.

Do not stop a pump without providing insulin another way.

A pump is the patient's only insulin and uses only rapid-acting insulin - stopping it with no replacement leads to rapid ketosis and DKA. When the pump comes off, insulin must go on by another route.

Do not assume the sensor or pump is the cause of the illness.

A person with diabetes gets sepsis, MI and every other illness; the device is visible but usually not the problem. Assess the patient, and treat the diabetes technology as one part of the picture.

Who owns it

The diabetes specialist team (paediatric diabetes team for a child) owns the technology and must be involved in every pump patient. Tell them the devices in use, the capillary glucose and ketones, whether the pump has been stopped and insulin replaced, and the clinical picture.

Who to call

The team and the criteria are national. The phone number is local, and this tool does not know it. Find it once, now, and write it on the department's own card — that is the part no website can do for you.

Say the device name first: Open with laryngectomy, LVAD, shunt — the single word changes who comes and what they bring. Do not bury it in the history.
Say what you have already established: Whether the device is patent, whether it has been removed or disturbed, and what you have already tried. The specialist is deciding whether to walk or run.
Ask who owns it out of hours: Device ownership and the on-call route often differ from the implanting specialty, and it is frequently a regional centre rather than your own hospital.
The patient's own team is a resource, not an afterthought: Named nurse specialists, home-care companies and device helplines answer questions nobody else can, and the patient usually has the number.

When the device is not the problem

A patient with a device gets pneumonia, sepsis, pulmonary oedema and myocardial infarction at the same rate as everybody else. The device is the most visible thing about them and it attracts the whole assessment.

The NTSP says it out loud: The project's own manual warns that patients with tracheostomies can become unwell with all the problems that other patients get too. It is easy to become fixated with the tracheostomy. The same sentence applies to every device in this tool.
Clear the device, then leave it: Establish that the device is doing its job — the stoma is patent, the line draws back, the pump is running — and then assess the patient as you would anyone else.
The anchoring runs both ways: The opposite error is treating a device complication as a medical illness: a blocked gastrostomy read as vomiting, a baclofen pump failure read as sepsis.

NTSP manual — Red flags · read in full

What the patient will be carrying

Patients (and parents) carry device details, settings and the diabetes team's contact, and are usually expert in their own technology. In an emergency they, or a medical alert, identify the pump and sensor.

Scope of this page

This page covers recognising an insulin pump and a glucose sensor in the ED and the safe first steps: tell the two devices apart, confirm glucose on blood not sensor, stop the pump and replace insulin in the unwell or DKA patient, and involve the diabetes team. It does not set pump settings, basal rates or the detailed DKA regimen (follow the adult JBDS DKA pathway, or the BSPED guideline in children, and the diabetes team). Used in adults and children; paediatric decisions are directed by the paediatric diabetes team.