Continuous glucose monitors in primary care: Transforming diabetes self-management

Overview of continuous glucose monitors

Blood glucose monitoring is a fundamental component of diabetes self-management, particularly for people using insulin.^{1, 2} Traditionally, this process involved multiple finger-prick tests throughout the day using blood glucose test strips and a handheld blood glucose meter; however, this method has several limitations.³ Frequent finger-prick testing can be a burden, making adherence to regular blood glucose monitoring challenging for some people. It also provides an isolated point-in-time glucose reading making it difficult to identify patterns.^{3, 4}

The introduction and increasing use of continuous glucose monitors (CGMs), both overseas and in New Zealand, has transformed diabetes self-management and motivated people to become more involved in their healthcare.² A CGM automatically detects and reports glucose levels in the interstitial fluid at regular intervals through a subcutaneous sensor, largely replacing the need for routine finger-prick testing. CGMs measure glucose levels every one to five minutes, providing a detailed glucose profile that can help to optimise insulin treatment and identify patterns of hypo- and hyperglycaemia. In addition to being more convenient and less invasive than traditional blood glucose monitoring, CGMs provide patients and healthcare professionals with more useful data to inform diabetes self-management, including their current glucose levels and the rate at which these are changing.⁴

Several international guidelines, including those from the American Diabetes Association, International Society for Pediatric and Adolescent Diabetes and the National Institute for Health and Care Excellence (NICE) recommend the use of CGMs, particularly in people treated with insulin.^{2, 5–7} The evidence of benefit is strongest in people living with type 1 diabetes, however, there is increasing evidence supporting the use of CGMs for people living with type 2 diabetes, irrespective of whether they are using insulin.^{2, 6}

Since October, 2024, CGMs have been funded in New Zealand with Special Authority approval for people diagnosed with type 1 diabetes, pancreatogenic and genetic forms of diabetes (Table 1). They are not currently funded for other types of diabetes, e.g. type 2 diabetes, gestational diabetes. Pharmaceutical dispensing data indicate a substantial rise in CGM use in New Zealand since they were first funded; almost 17,000 people were dispensed a CGM in 2024, increasing to ~30,000 people in 2025.⁸ N.B. Some people may have trialled multiple CGM models within a year and may therefore have been counted more than once.

Behind the scenes: Understanding the technology of CGMs

A CGM is composed of a sensor, transmitter and receiver. A disposable applicator is used to apply the sensor to the skin. When the applicator is pressed to the skin, it inserts a filament-like sensor in the subcutaneous layer, which measures glucose levels in the interstitial fluid.^{2, 3} The sensors available in New Zealand contain an enzyme, most commonly glucose oxidase, which reacts with glucose in the interstitial fluid and generates an electrical signal that is proportional to the glucose concentration.¹ The level of glucose in interstitial fluid is very similar to the level in blood, but may lag behind blood glucose by approximately five minutes when levels change rapidly.^{3, 9} Finger-prick testing is therefore still indicated in certain circumstances, e.g. when glucose levels rise or fall rapidly, when hypoglycaemia is detected by the sensor or when symptoms do not match sensor readings.^{3, 10}

The electrical signal generated by the sensor is processed into a glucose reading and transmitted via Bluetooth to a receiver device.¹ Most people use their smartphone as the receiver, but standalone receiver devices are available from some suppliers. CGMs that integrate with insulin pumps can display glucose readings on the pump screen also. Almost all modern CGMs function as real-time devices, where they automatically and continuously transmit data to the receiver without requiring a manual “swipe” of the sensor which was the case with some older CGM systems.^{3, 4}

The receiver displays the current glucose reading, past readings and trends, e.g. time in, above and below range (see: “CGM data at a glance”). CGMs also have alarm features which alert users to certain scenarios, including hypoglycaemia; this can help reduce anxiety about glucose levels, particularly at night. CGM data can usually be shared with family/whānau, carers and healthcare professionals, facilitating remote glucose monitoring. This can be particularly beneficial for some people, e.g. young children, older adults living alone.

The use of CGMs in type 1 diabetes

CGMs are now considered a fundamental component of diabetes self-management for people living with type 1 diabetes and should ideally be introduced from diagnosis.^{2, 6} Numerous studies have shown that CGM use can reduce HbA_1c levels and the frequency of hypoglycaemic episodes, and increase time spent in the target glucose range.^{2, 6} CGMs can also improve treatment satisfaction and quality of life, and reduce diabetes distress.^{2, 6} Being able to visualise the immediate glycaemic effect of dietary choices, physical activity, stress, sleep and illness can help people living with type 1 diabetes to better understand factors affecting glycaemic control, supporting more informed self-management decisions and lifestyle changes.^{11, 12}

CGMs are generally accepted by the majority of people living with diabetes, however, certain factors can limit uptake and ongoing use, such as a lack of dexterity to apply the sensor, discomfort, perceived image of wearing the device (i.e. body image concerns, stigma) and the ability to use and trust technology.^{12, 13} For some people, continuous access to data can also be a source of anxiety.¹³

Pairing with an insulin pump

Some CGMs (interoperable CGMs) can be wirelessly paired with an insulin pump and insulin dosing algorithm to form an automated insulin delivery (AID) or closed-loop system; this is now considered the standard of care for many people living with type 1 diabetes, as it replaces the need for multiple daily insulin injections.² The CGM detects glucose levels and transmits data to the insulin pump; the dosing algorithm (software either on the insulin pump or a smartphone app) interprets the glucose readings and adjusts insulin delivery from the pump accordingly.^{1, 10} Two insulin pumps are currently funded with Special Authority approval in New Zealand: Tandem t:slim X2 (with Control-IQ+ algorithm) and mylife YpsoPump (with CamAPS FX algorithm). All funded interoperable CGMs work with either of the funded insulin pumps.

Patients are generally initiated on an insulin pump within a secondary care multidisciplinary diabetes service, as it is a resource-intensive process that requires specialised expertise and patient education. Specialist involvement is not a requirement for funded treatment, however, insulin pumps are not expected to be initiated in primary care.

CGMs for type 2 diabetes: A new era?

The role of CGMs for people living with type 2 diabetes is emerging.¹⁴ Improvements across a range of glycaemic parameters have been reported with CGM use in people living with type 2 diabetes taking insulin, including HbA_1c, time in range and time above range.^{2, 15} Greater treatment satisfaction and reduced diabetes distress have also been reported.^{2, 15} The evidence base for CGMs in people living with type 2 diabetes not taking insulin is still evolving, but studies generally demonstrate benefits in glycaemic outcomes and patient experience.^{2, 16, 17} CGMs can be particularly useful as an educational tool for people living with type 2 diabetes, helping them to understand how certain factors, e.g. food choices, affect glucose levels. This information can motivate positive behavioural changes.^{1, 2} While continuous CGM use is preferable, intermittent use can also be beneficial.² For example, a patient living with type 2 diabetes may choose to self-fund a single CGM sensor when they are first diagnosed to understand how factors affect their glucose levels. This would provide them with 10 – 15 days of data to help inform lifestyle changes and ongoing self-management.

CGM recommendations for type 2 diabetes management

New Zealand guidance on the use of CGMs for type 2 diabetes is limited. The New Zealand Society for the Study of Diabetes advises that the finger-prick method or a CGM can be used for glucose self-monitoring.¹⁸ The guidance notes that CGMs may be particularly beneficial when finger-prick blood glucose monitoring does not provide sufficient information, and should be considered when inadequate blood glucose monitoring affects patient safety or delays treatment decisions.¹⁸

The 2026 Standards of Care guidance from the American Diabetes Association recommends CGMs for all people living with diabetes who need insulin or who take non-insulin glucose-lowering medicines that can cause hypoglycaemia (e.g. sulfonylureas).² A CGM is also recommended for people who take any glucose-lowering treatment where a CGM would improve management.² This could include those who are newly diagnosed with type 2 diabetes, have not achieved glycaemic targets, are unable to check blood glucose levels (e.g. physical and/or cognitive impairment, children) or who have another clinical need for monitoring (e.g. during pregnancy, people at risk of hypoglycaemia, such as during an illness).^{3, 5, 19}

As CGMs are not funded for people diagnosed with type 2 diabetes, cost is a major barrier to access in New Zealand. However, the option of self-funding treatment should still be discussed so patients can consider it depending on their individual circumstances. For some patients, intermittent CGM use may be an affordable alternative to continuous use, e.g. used on occasion to understand factors affecting glucose levels, or to assess effectiveness of lifestyle changes or treatment. The cost of a CGM varies between models (Table 3) and pharmacies. Some suppliers offer free trials, and some PHOs fund CGMs for select patients diagnosed with type 2 diabetes. Use of a disability allowance may also be an option (see: “Supporting patients to access CGMs via the disability allowance”).

Two types of CGMs are funded in New Zealand: standalone and interoperable

Pharmac currently funds five CGM models via Special Authority for people diagnosed with type 1 diabetes, pancreatogenic and genetic forms of diabetes (Table 1). CGMs are not funded for people diagnosed with type 2 diabetes (or other types not covered by the criteria, e.g. gestational diabetes), however, they can be purchased; standalone devices are generally the most suitable option (see below).

The five funded CGMs can be categorised into:

• Standalone: Dexcom ONE+ and FreeStyle Libre 2 Plus. These CGMs do not have the ability to work with an insulin pump, but they can be worn alongside an insulin pump as separate unlinked devices; this is known as a manual/open loop system.¹⁰ Other standalone CGMs are also available in New Zealand that can be purchased, e.g. CareSens Air, LinX.
• Interoperable: Dexcom G6^* and G7, FreeStyle Libre 3 Plus. These CGMs can integrate with an insulin pump. They are funded on the basis that the person would benefit from an insulin pump to create an AID system (see: “Pairing with an insulin pump”).
  • It is recommended that Special Authority applications for interoperable CGMs be made by clinicians working in a secondary care setting, as part of a multidisciplinary diabetes team. However, specialist involvement is not a requirement for funded treatment.

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Table 1. Special Authority criteria for CGMs in New Zealand.²⁰ Applications can be made by any relevant practitioner, and approvals are valid without further renewal.

Standalone CGM (SA2538)	Interoperable CGM (SA2537)
Dexcom ONE+ FreeStyle Libre 2 Plus	Dexcom G7 FreeStyle Libre 3 Plus Dexcom G6 (no new patients – see note below)*
Patient has type 1 diabetes; OR Patient has permanent neonatal diabetes or specific monogenic diabetes subtypes with insulin deficiency, and is considered by the treating endocrinologist or relevant secondary healthcare professional (as practicable) as likely to benefit; OR Patient has type 3c diabetes (includes insulin deficiency due to pancreatectomy or secondary to pancreatitis or cystic fibrosis), and is considered by the treating endocrinologist or relevant secondary healthcare professional (as practicable) as likely to benefit; OR Patient has an atypical inherited form of diabetes	Meet one of the criteria in SA2538; AND In the opinion of the treating relevant practitioner, the patient would benefit from an AID system

* The Dexcom G6 CGM is currently also funded but is being discontinued and will no longer be funded in New Zealand from early 2027.²¹ Prescribers should ensure that no new patients are started on the Dexcom G6 and begin transitioning patients currently using this model to an alternative funded interoperable CGM.

Funded CGM limits apply

Each CGM model has a maximum number of sensors that will be funded per three-month prescription and per year (Table 2). Occasionally, there may be a clinical reason that a patient requires more CGMs than the funded limits; in this instance, it may be appropriate to apply for an increased allocation of funded CGMs via the Special Authority waiver process.²²

CGM suppliers will usually provide free replacement sensors directly to patients if there is a technical fault with a sensor, and this does not count towards their funded CGM limits. Patients who experience a faulty CGM should contact the supplier directly (see: “Providing practical CGM education to patients”).

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Table 2. Funded CGM limits.²⁰

	Maximum funded per three-month prescription	Maximum funded per year
Dexcom ONE+	Nine sensors	40 sensors
FreeStyle Libre 2 Plus	Six sensors	28 sensors
Dexcom G6	One pack (nine sensors and one transmitter)*	Five packs
Dexcom G7	Nine sensors	40 sensors
FreeStyle Libre 3 Plus	Six sensors	28 sensors

* The Dexcom G6 (to be discontinued early 2027) is an older generation design that consists of a disposable sensor and a reusable transmitter that clip together to form a single device. Newer CGMs, e.g. Dexcom G7, have an integrated transmitter and sensor, so the entire device is replaced when the sensor expires.

Practice Tip: Include technical support details on the CGM prescription to make it easier for patients to access assistance, e.g. “contact NZMS 0508 634 103 for technical support or submit an online NZMS support form” for Dexcom CGMs, and “contact Mediray 0800 106 100, option 2 for technical support” for FreeStyle Libre CGMs.

Alternative brand allowance pathway

The funded range of CGMs will meet the needs of most eligible people diagnosed with diabetes. However, there may be circumstances in which a funded CGM is not clinically appropriate, or where there is a clinical need for continued use of a different model, e.g. patients with a significant cognitive impairment or physical disability which would make it difficult for them to learn a new system. In these limited situations, clinicians can apply for an Alternative Brand Allowance (ABA) under the Pharmac Exceptional Circumstances Framework. The application must clearly document why funded CGMs are unsuitable or why an alternative CGM is required.

Choosing the right CGM for a patient

For most patients, it is recommended that they are initiated on a standalone CGM first, even if they will eventually switch to an AID system. The choice of specific CGM should be individualised, based on device features that are most important to the patient, e.g. wear time, alerts (Table 3).¹ Cost will also factor into this decision for patients who choose to self-fund CGMs (see below). Patients should check app compatibility on their smartphone, or that a receiver device is available, prior to making a choice of CGM to ensure they will be able to view and share their data. Some patients may need to trial different CGM models before finding the option that best suits their needs.

Patients who are self-funding CGMs, e.g. those diagnosed with type 2 diabetes, can choose any CGM model that is available (if it is compatible with their smartphone or a receiver device is accessible). Standalone CGMs will generally be the most appropriate option, but some interoperable models can also be used as a standalone CGM and the additional features may be preferable for some patients.²³ Patients self-funding CGMs do not require a prescription and can purchase them directly via the supplier if preferred.

Seek diabetes specialist advice if there is uncertainty about whether a CGM should be initiated, or for patients wanting to switch to an AID system