Continuous Glucose Monitoring

Definition/Description

Continuous Glucose Monitoring (CGM) is via a sensor worn just under the skin which reads the glucose saturation in the interstitial fluid. The use of CGM is beneficial in supporting the management and blood glucose control of those with Type 1 diabetes, especially those who have recurrent and serious issues such as hypoglycaemia or hyyperglycaemia requiring medical intervention or hospital admission.

Further information on the CGM systems can be found on the Diabetes UK website here

Alongside CGM there is also Flash Glucose Monitoring. Unlike CGM, Flash monitoring is not real time and requires a secondary device to scan for readings. CGM monitors blood sugar level continuously and sends data to the display device (a hand held monitor or pump) so warnings for high, low or rate of change can be alerted. With flash glucose monitoring it is only when the sensor is scanned that glucose reading and trends can be observed.

Red Flag Symptoms

If a patient is currently experiencing:-

severe hypoglycaemia - support with appropriate carbohydtrate to treat, if unresponsive call an ambulance
hyperglycaemia (Diabetic Ketone Acidosis) - follow urgent scenario as with diagnosis

Exclude Red Flag Symptoms

Currently having a severe hypoglycaemic episode
Currently experiencing hyperglycaemia
Urine analysis indicating high levels of ketones (Diabetic Ketone Acidosis - DKA)
Those not meeting referral criteria

Do Not Refer

People with Type 2 diabetes
Those with Type 1 diabetes within HbA1c ranges and not encountering issues with hypoglycaemia
Those people with type 1 diabetes who have not received structured education

Guidelines on Management

NICE guidance for Type 1 Diabetes Mellitus Diagnosis and Management (nice.org.uk/guidance/ng17) recommends the person with diabetes should monitor blood glucose as a minimum 4 times every day and up to 7-10 times a day in order to achieve recommended target HbA1c of 48mmol/mol and detect and manage potential hypoglycaemia.

The guidance also states – “Advise adults with type1 diabetes to aim for: a fasting plasma glucose level of 5–7mmol/litre on waking and a plasma glucose level of 4–7mmol/litre before meals at other times of the day”.

Whilst Flash Glucose Monitoring (Frestyle Libre^TM) has been made available on perscription, appropriatness and induction for the use of CGM or Flash monitoring is required from the Diabetes Specialist Team. To support this pathway the Freestlye Libre^TMhas been added to the "red" prescribing list by the Hull and East Riding Prescribing Committee(HERPC). Policies for the devices have been created for both East Riding of Yorkshire CCG and Hull CCG to support.

Referral Criteria/Information

Provision of such equipment requires support and education to the person or carer. Therefore this equipment and its supplies should only be initiated and supplied by the Diabetes Specialist Team. Flash Glucose Monitoring (FGM) such as Freestyle Libre® should not be prescribed by GP practices/primary care and as such would be classed as a RED drug i.e. only for hospital specialist prescribing/supply.

More than 1 episode a year of severe hypoglycaemia with no obviously preventable precipitating cause.
Complete loss of awareness of hypoglycaemia.
Frequent (more than 2 episodes a week) asymptomatic hypoglycaemia that is causing problems with daily activities.
Extreme fear of hypoglycaemia.
Hyperglycaemia (HbA1c level of 75mmol/mol [9%] or higher) that persists despite testing at least 10 times a day
Hyperglycaemia (HbA1c level of 84mmol/mol (10%) or higher in an individual and/or recurrent hospital admissions with DKA who is not achieving recommended traditional SBGM testing frequency but with flash glucose monitoring, is able to achieve and maintain a drop in HbA1c of at least 12mmol/mol and/or a reduction in hospital admissions due to DKA.

Criteria 1-5 are NICE guidance criteria for real-time continuous glucose monitoring and align closely with the criteria for CSII (continuous subcutaneous insulin infusion) therapy. Please see attached flowchart outlining the expected therapeutic pathway to be followed by the specialist team at Hull & East Yorkshire NHS Hospitals Trust in supporting such patients.

"Where a patient doesn't meet the current funding criteria, self-funding is an option. Continuing costs must be met by the patient where self-funding is in place".

Criteria 6 is a locally agreed criteria which identifies a group at very high risk of costly diabetes complications in whom flash glucose monitoring enables them to achieve much tighter glucose control thereby reducing significantly the risk of complications and offsetting the cost of future complications and hospital admissions.

The majority of people with diabetes eligble for a CGM or Flash monitoring are already known to, or in the care of the Diabetes Centre. However if you are unsure on the appropriatness or if the patient is seen by the diabetes specialist team please use the advice and guidance for diabetes via NHS e-Referrals Service