Who Benefits From Continuous Glucose Monitoring?

Kevin Fernando, MBChB, MSc


June 30, 2023

Kevin Fernando, MBChB, MSc

The use of diabetes technology (specifically for blood glucose monitoring) has advanced at an almost exponential rate over the past few years. Continuous glucose monitoring (CGM) is now well established in the United Kingdom as the standard of care for my patients with type 1 diabetes and has been initiated and interpreted almost entirely by my hospital colleagues.

In my patients with type 1 diabetes, CGM can achieve these results:

  • Increase time spent in their target blood glucose range and improve A1c to help reduce future risk for diabetes complications

  • Allow easier identification of nocturnal hypoglycemia, which can have a debilitating impact on quality of life

  • Improve patient satisfaction, which can positively affect quality of life and aid engagement with healthcare professionals

Appropriate use of CGM can also be transformative for many of my patients with type 2 diabetes. It can empower these individuals, help support self-care, and reduce the burden of type 2 diabetes on the patient.

Moreover, why is a patient of mine with type 1 diabetes eligible for CGM, while a patient with type 2 diabetes on a similar insulin regimen is not? This is not equity of care; both patients could reap the benefits for glucose management and quality of life.

Fortunately, recently updated UK NICE guidance covering the management of adults with type 2 diabetes has opened the doors to CGM for many of my patients with type 2 diabetes, albeit with several caveats.

Specifically, NICE recommends that I offer intermittently scanned CGM (isCGM) to my patients with type 2 diabetes on multiple daily insulin injections (two or more daily insulin injections, which could be either a basal-bolus regimen or more than one daily insulin injection) in these clinical situations:

  • A history of recurrent or severe hypoglycemia or impaired awareness of hypoglycemia

  • A condition or disability (including a learning disability or cognitive impairment) that means that my patient cannot monitor his or her blood glucose by capillary blood glucose monitoring but could use an isCGM device (or have it scanned for him or her)

  • A requirement for my patient to check his or her blood glucose at least eight times daily

  • A patient who would otherwise need help from a care worker or healthcare professional to monitor his or her blood glucose (eg, a patient with frailty)

Of note, NICE also recommends that I consider real-time CGM (rtCGM) as an alternative to isCGM if it is available for the same or lower cost. There are now rtCGM systems available via NHS prescription in the UK that fulfill this criterion.

While this guidance is a significant step forward for my patients with type 2 diabetes, these recommendations are restrictive. I see CGM as a potential educational tool for all my patients with type 2 diabetes, regardless of their treatment regimen, comorbidities, or complications.

If a patient can use the information from a CGM device to make and sustain clinically meaningful changes to his or her lifestyle (eg, dietary changes), then I am happy to prescribe a CGM, irrespective of the patient's treatment regimen.

Furthermore, CGM data can be uploaded to share online with clinicians and carers involved in managing the patient with type 2 diabetes. This step can facilitate more effective and holistic diabetes reviews and also can allow the more efficient use of remote consultations.

I appreciate that my approach is aspirational, given the current costs of CGM devices, but the potential of CGM to facilitate lifestyle changes, improve adherence to treatment, and allow a better understanding of glucose patterns to aid self-management overall cannot be underestimated.

Sadly, my youngest patient with type 2 diabetes and obesity is only in her early 20s. I have escalated her treatment to triple therapy with metformin, an SGLT2 inhibitor, and a GLP-1 receptor agonist. I gave her an urgent referral to my local weight management service for weight, nutritional, and psychological support. I have also issued her an rtCGM device. While she does not meet any of the above UK criteria for using CGM, I feel that the role of CGM as an educational tool for her is invaluable and equally important to her pharmacologic therapies.

At the recent ADA 2023 congress in San Diego, California, I attended a symposium entitled "CGM in Type 2 Diabetes: Are We There Yet?" which discussed the expanding evidence base for CGM use. This session validated my expanding use of CGM in patients with type 2 diabetes, as the evidence presented (eg, the IMMEDIATE study) suggested that for patients using noninsulin therapies, isCGM results in greater time in range and lower A1c without increasing hypoglycemia or worsening diabetes distress.

The symposium also made me consider CGM in certain individuals without type 2 diabetes. Speakers highlighted pilot studies that used CGM as a behavioral tool or lifestyle-change tool for patients with obesity and prediabetes. CGM was found valuable for influencing decisions regarding diet and exercise. It also improved body composition.

The session concluded that rather than being used as a "reactive device" for hypoglycemia prevention and glycemic management, rtCGM should be assessed as a prevention tool.

I also use CGM when de-escalating therapies (eg, simplifying insulin regimens), particularly in my frail older patients in institutionalized care. Brief use of CGM can provide valuable information to help reduce insulin doses or switch from twice-daily insulin regimens to once-daily, long-acting insulin regimens. Such a strategy reduces the risk for hypoglycemia and improves quality of life, and also reduces the workload for my already overburdened nursing colleagues.

However, the widening use of CGM in primary care requires education and support for patients with type 2 diabetes who are using it and for healthcare professionals who will be initiating and interpreting the data.

Already, my colleagues in primary care are telling me that they are overwhelmed by the advances in diabetes technology. They are worried about having to interpret a deluge of ambulatory glucose profiles and make treatment alterations accordingly. There have also been legitimate concerns about the digital literacy of certain patients, data protection impact assessments, and ownership of data.

Primary care doctors, however, are the custodians for the management of type 2 diabetes in most countries in the world, and consideration of CGM should be an integral part of our regular diabetes reviews. Early and appropriate initiation of CGM can improve quality, and potentially length, of life.

Dr Fernando is a general practitioner near Edinburgh, Scotland, with a specialist interest in diabetes; cardiovascular, renal, and metabolic diseases; and medical education.

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