CGM Update in Healthcare Settings
By Nicole McClure (RN, Credentialled Diabetes Educator)
Managing diabetes is demanding and complex. A critical part of day to day diabetes management, particularly for those who manage their diabetes with insulin, is glucose monitoring. When blood glucose levels (BGLs) are in target both long- and short-term complications of diabetes can be minimised. Glucose levels outside target ranges during hospitalisation can negatively impact on morbidity, recovery and discharge.
Diabetes technologies including continuous glucose monitoring (CGM), flash glucose monitoring (Flash GM) and continuous subcutaneous insulin infusion (CSII) via insulin pump have been developed with the aim of increasing the time that glucose levels are within target.
People with diabetes are increasingly using CGM and Flash GM technology. Improvements in diabetes technology and the ability for CGM integration with CSII have created automated insulin delivery (AID) systems. The use of AIDs is becoming increasingly popular. Two AID systems are currently approved by the Therapeutic Goods Association (TGA) in Australia – Medtronic 670G, 770G, and 780G; and Tandem Control-IQ with t:slim X2 pump.
One of the barriers to technology use for people with diabetes is cost. Since 2017, fully funded access to CGM technology has been available in Australia through the National Diabetes Services Scheme (NDSS) for those under the age of 21 years who live with type 1 diabetes or conditions similar to type 1 diabetes.
Access was extended in 2020 to adults with type 1 diabetes who were pregnant or planning a pregnancy, and those with concessional status. From the 1st of July 2022, all people with type 1 diabetes are eligible to access subsidised CGM and Flash GM technology.
Those people with type 1 diabetes not eligible for full subsidy pay a co-payment of $32.00/month to access CGM and Flash GM technology. This has greatly reduced the financial burden for people living with diabetes who may have been paying over $5000/year to privately access this technology prior to the introduction of the subsidy.
In Australia, audit data showed 23% of adults and 62% of youth under 21 years with type 1 diabetes used CGM technology (Table 1). This likely reflects the longer availability of fully funded CGM and Flash GM technology for youth under 21 years.
It is expected that CGM and Flash GM technology use in adults with type 1 diabetes will increase with the recent subsidy expansion. If you work in a hospital or other healthcare setting, it is now more likely than ever that you will encounter people who want to continue to use their CGMs and AID systems during admission.
CGM, Flash GM and CSII are designed for home use by individuals with diabetes. Intermittent finger-prick capillary BGL (blood glucose level) using a quality-controlled device is the current method for assessing glucose levels in healthcare settings. Compared with finger prick BGL, CGM offers a large amount of real-time and aggregated summary data which can be extremely valuable for both the person with diabetes and their health care team.
Both CGM and Flash GM systems display the current glucose level, it’s direction and rate of change and have the ability to alert the user or their carers when glucose readings are out of range. Some systems are able to predict glucose values 20-30 minutes into the future and alert the user to impending hypo- or hyperglycaemia.
There is good evidence that use of these diabetes technologies usually improve BGLs and reduce the incidence of severe and nocturnal hypoglycaemia.¹ The more the person uses and responds to CGM data the greater the benefits.²
Trials (largely experimental) of these devices in healthcare settings by admitted patients has demonstrated the potential to predict and minimise hypo- and hyperglycaemia and improve health outcomes.³ They could have particular benefits for those patients with reduced awareness of symptoms of hypoglycaemia.
Conversely, removing CGM, Flash GM or AID technologies from the person with diabetes on admission has the potential to decrease patient satisfaction and quality of care.
Technological improvements with currently available CGM and Flash GMs have allowed some devices to be approved for treatment decisions without the need for confirmation with finger prick BGL. Despite this, concerns about accurate and reliable measurement of glucose levels have prevented the expansion of CGM and Flash GM use into hospital settings.
CGM and Flash GM measure interstitial glucose which closely correlates but lags behind blood glucose. Lag time can vary from a few minutes to up to 10 to 15 minutes. CGM and Flash GM devices may be less accurate when glucose levels are less than 2.2mmol/L and greater than 27.7mmol/L, and may overestimate hypoglycaemia. 4 Reduced tissue perfusion, hypotension, hypothermia, hypoxia, oedema and vasopressor use may affect accuracy of CGM and Flash GM readings.5
CGM and Flash GM devices are not approved for use with exposure to x-rays, diathermy, CT and MRI due to concerns that device function and accuracy may be affected. Ascorbic acid, hydroxyurea and acetaminophen are known to interfere with the accuracy of some CGM and Flash GM devices. 5
The use of diabetes technologies in healthcare settings offers many potential benefits to patients and clinicians. Until further studies and improvements address data accuracy concerns, CGM and Flash GM technology may not be able to completely replace the need for finger prick BGL monitoring during a hospital stay.
To safely utilise new diabetes technologies in healthcare settings would also require the establishment of policies and processes for collecting, reviewing, storing and responding to CGM or Flash GM data, as well for staff training.
To learn more read other related articles here:
1. Pease, A. et al. (2021). Glycaemia and utilisation of technology across the lifespan of adults with type 1 diabetes: Results of the Australian National Diabetes Audit (ANDA). Diabetes research and clinical practice, 171, 108609. https://doi.org/10.1016/j.diabres.2020.108609
2. Living Evidence for Diabetes Consortium. Australian Evidence-Based Clinical Guidelines for Diabetes 2020. Melbourne, Australia.
3. Rodolfo, G. et al (2020). Comparison of the FreeStyle Libre Pro Flash continuous glucose monitoring (CGM) system and point-of-care capillary glucose testing in hospitalized patients with type 2 diabetes treated with basal-bolus insulin regimen. Diabetes Care, 43: 2730-2735. Accessed on 17/09/2022; https://doi.org/10.2337/dc19-2073
4. Krinsley, J.S. et al. (2017). Continuous glucose monitoring in the ICU: clinical considerations and consensus. Critical Care, 21: 197 accessed 14/09/2022; DOI 10.1186/s13054-017-1784-0