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Wednesday 11 May 2022 10:11am

EDOR researchers from the Department of Women's and Children's Health, University of Otago, have recently published a review on the effectiveness of continuous glucose monitoring technologies on glycaemic control in individuals with type 1 diabetes.

Their systematic review and meta-analysis of randomized control trials found that continuous glucose monitoring (CGM) technologies were more effective at controlling blood glucose levels than the traditional capillary glucose monitoring (sometimes referred to as the "finger prick" blood glucose test).

However, the effectiveness of these devices at improving blood glucose control differed depending on the type of CGM technology used.

What is Type 1 Diabetes Mellitus?

Type 1 diabetes is a life-long condition where an individual does not produce enough insulin. It is an auto-immune disease - cells in the pancreas which make and secrete insulin are destroyed by the immune system.

Our body creates insulin to clear glucose (sugar) from our blood. We all need glucose in our blood to fuel our brain and our body, however too much glucose in our blood can cause damage to our body over time.

People who develop type 1 diabetes have a considerable life-long burden of managing their glucose levels.

How do CGM devices work to manage Type 1 Diabetes?

Continuous glucose monitoring (CGM) technology has been designed to improve blood glucose control in type 1 diabetes. The device is inserted into the interstitial tissue, and measures interstitial glucose continuously, as a proxy for blood glucose levels. Several different types of CGM technology exist:

Intermittently scanned CGM technology (Abbott Freestyle Libre) only provides glucose values intermittently when the device is scanned, and therefore cannot provide glucose alarms or be linked to automated insulin pumps/artificial pancreas devices.

Real-time CGM technology monitor glucose levels continuously, and can provide high and low glucose alerts/alarms.  These devices can commonly be linked with automatic insulin pumps and similar technology to significantly reduce the burden of managing type 1 diabetes.  Two types of Real-time CGM technology exist:

  1. Adjunctive CGM technology continuously monitor glucose levels, however they require a capillary blood glucose test to confirm the result or make treatment decisions (these are usually older technology)
  2. Non-adjunctive Real-time CGM technology continuously monitor glucose levels, and do not require a capillary glucose test to confirm the result or make treatment decisions.

Which CGM technology is most effective at improving glycaemic control?

EDOR researchers analysed data from randomised controlled trials that assessed the effectiveness of different CGM technologies, compared to the traditional capillary blood glucose testing. Previous meta-analyses have only looked at the effectiveness of all CGM technologies together, or only included older CGM technologies.

The authors found that:

  • The real-time CGMs were effective at reducing HbA1c (a measure of long term glucose control), regardless of whether the CGM device required a finger prick blood test to confirm blood glucose level.
  • The CGM devices that require the person to intermittently scan the device to get a glucose reading, showed no improvement in HbA1c compared with traditional capillary glucose monitoring.
  • All CGM technologies showed improvement in other standardized measures of blood glucose control, including hypoglycaemia and time in range (a measure of the amount of time the participants blood glucose levels were at an appropriate level).
  • The newer non-adjunctive CGMs (those that do not require a finger prick test to confirm) appeared the most effective at improving the time in range.

What does this mean for the treatment of Type 1 Diabetes?

Results from this meta-analysis show that all types of CGM technologies are effective at improving glucose control, especially for time in range and also for reducing the burden of hypoglycaemia.

Associate Professor Ben Wheeler, co-author of the meta-analysis and paediatric endocrinologist, also highlighted that this research shows the limitations of using HbA1c to measure glucose control in people with type 1 diabetes.

"This study contributes to growing evidence that HbA1c as a tool is less sensitive at measuring glucose variability. The CGM metrics of time in range and time in hypoglycaemia seem much more important for reflecting the burden of living with diabetes."

Using CGM can provide considerable peace of mind for people living with or caring for a person with type 1 diabetes, especially when they have access to the real-time devices that send alerts when glucose levels are high or low.

What other technology exists for the treatment of Type 1 Diabetes?

Artificial pancreas technologies, which combine insulin pumps and CGM with computer algorithms, are now available and funded for some people through PHARMAC.

These offer much promise for improving glucose control and preventing future complications, in addition to considerably reducing disease burden.

Are CGM devices and other technologies accessible in New Zealand?

Although PHARMAC does fund insulin pumps for some people, CGM technology is not funded and can cost someone with type 1 diabetes over $2000 per year.

Professor Wheeler says that due to the cost of these technologies, there are considerable inequities in the access to these treatments:

"It is essential that we all continue to strongly and urgently advocate for these life changing and saving technologies to be funded by PHARMAC."

Read the journal article

Effect of divergent continuous glucose monitoring technologies on glycaemic control in type 1 diabetes mellitus: A systematic review and meta-analysis of randomised controlled trials. Elbalshy, M., Haszard, J., Smith, H., Kuroko, S., Galland, B., Oliver, N., Shah, V., de Bock, M. I., & Wheeler, B. J. (2022). Diabetic Medicine. e14854. Advance online publication.

Read more about this research

Diabetes & Obesity Research Review - Issue 157 (PDF 1.5MB)

Learn more about EDOR's Diabetes research

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