Key Messages

• Oral glucose-lowering medicines were dispensed to 4.4% of enrolled patients aged 20 years or older in New Zealand in 2018
• Dispensing rates are highest for people aged 70–79 years (11.2%) and Pacific peoples (7.4%) with lower rates in Māori (3.8%) and people of European/Other ethnicity (2.9%)
• Just over two-thirds of people with type 2 diabetes are also taking cardiovascular and renoprotective medicines, as recommended:
  • 68% were dispensed an angiotensin-converting enzyme (ACE) inhibitor or angiotensin-receptor blocker (ARB)
  • 40% were dispensed another blood pressure-lowering medicine, i.e. a calcium channel blocker, thiazide diuretic or beta-blocker^*
  • 25% were not dispensed any blood pressure-lowering medicines
  • 68% were dispensed a statin
• Polypharmacy is the norm in patients with type 2 diabetes (also a reflection of age):
  • 45% were dispensed between five and nine long-term^† medicines
  • 35% were dispensed ten or more long-term medicines
• Regular medicine review allows treatment to be adapted to the changing needs of the patient and reduces the risk of prescribing contributing to adverse outcomes

^* 83% of these patients were also dispensed an ACE inhibitor or an ARB

^† Two or more dispensings of that medicine in 2018 including oral glucose-lowering medicines and excluding medicines prescribed once, e.g. a course of antibiotics, or prescription items such as glucose testing strips and or insulin injection equipment

Which patients are taking oral glucose-lowering medicines?

Dispensing data shows that 164,751 people in New Zealand received oral glucose-lowering medicines in 2018^*, equivalent to 36 patients per 1,000 population.

^* Patients with type 2 diabetes were identified by having two or more dispensings of metformin, sulphonylureas, pioglitazone, vildagliptin, acarbose or combination formulations during 2018. This will not include patients who are managed by lifestyle interventions alone. A small proportion of patients will have received metformin for impaired glucose tolerance (and have not developed diabetes), weight loss or polycystic ovary syndrome.

Dispensing rates for females and males

Males (39.6) had a slightly higher rate of dispensings of oral glucose-lowering medicines per 1000 population than females (32.7) in 2018. This is consistent with studies showing the prevalence of type 2 diabetes is higher in males than females.

Dispensing rates by age

As patients age the dispensing rate of oral glucose-lowering medicines increases (Figure 1), mirroring the increasing prevalence of diabetes in older age groups. The highest rate of dispensing occurs in people aged 70–79 years. In patients aged 80 years and older the dispensing rate of oral glucose-lowering medicines decreases reflecting an increased focus on maintaining quality of life and minimising the risks associated with stringent glycaemic targets.

Dispensing rates by ethnicity

Pacific peoples (7.4%) are dispensed oral glucose-lowering medicines at a higher rate per population than Māori (3.8%) or people of European ethnicity (2.9%) (Figure 2). This can be partly explained by the higher prevalence of type 2 diabetes which was estimated to be 15.7% for Pacific peoples, 9.3% for Māori and 5.2% for people of European/Other ethnicity in the 2017/18 New Zealand Health Survey in people aged over 25 years.^4* However, due to difficulties in quantifying the prevalence of type 2 diabetes in New Zealand, and the number of patients managed by lifestyle interventions alone, it cannot be accurately determined whether this rate of prescribing is appropriate for each ethnicity. Māori and Pacific peoples are not only more likely to develop type 2 diabetes they are more likely to develop it at an earlier age and more likely to develop diabetes-related complications. It would therefore be expected that type 2 diabetes in Māori and Pacific peoples would be generally treated more intensively with higher dispensing rates for oral glucose-lowering medicines and less lifestyle only management than people of European ethnicity.

^*There are two principle sources for estimating the prevalence of type 2 diabetes in New Zealand and both have limitations. The Virtual Diabetes Register determines the prevalence of diabetes via people’s use of diabetes health services, however, this data set does not differentiate between people with type 1 and type 2 diabetes. The New Zealand Health Survey (2017/18) interviewed 18,592 people and asked if they had ever been diagnosed with diabetes and assumed that those diagnosed after age 25 years have type 2 diabetes. This Survey is limited by its sampling method and the accuracy of the response of the participants.

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Insulin use in patients with type 2 diabetes

Nationally, 38,424 (23%) enrolled patients dispensed oral glucose-lowering medicines were also dispensed insulin in 2018. The percentage of insulin use was similar across people of European ethnicity (24%), Māori (27%) and Pacific peoples (26%), although usage was lower in those of Asian ethnicity (16%). However, as Māori and Pacific peoples with type 2 diabetes have a higher rate of diabetes-related complications than people of European ethnicity,¹ it might be expected that the percentage of insulin prescribing for Māori and Pacific peoples would be higher. For example, Māori and Pacific peoples were 6.5 times more likely to receive a kidney transplant due to the complications of type 2 diabetes (2008–2012) compared to people of other ethnicities.²

Insulin initiation for type 2 diabetes is generally appropriate for patients who have not achieved glycaemic control with the optimal use of two oral glucose-lowering medicines, or for those with a high HbA_1c at diagnosis, e.g. > 75 mmol/mol.³

Managing cardiovascular and renal risk in patients with type 2 diabetes

In addition to glucose-lowering interventions, people with type 2 diabetes generally require other treatments to reduce their risk of cardiovascular and renal disease. Typically, this will include blood pressure lowering-medicines and statins. Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) are recommended for people with diabetes and hypertension and/or albuminuria because they improve cardiovascular and renal outcomes by lowering blood pressure and providing additional renal protection.

Other medicines dispensed to patients receiving oral glucose-lowering medicines

Nationally, just over two-thirds of people with type 2 diabetes are also taking ACE inhibitors or ARBs, and/or statins, in accordance with guidelines. While a large proportion of people with type 2 diabetes are taking some form of blood pressure-lowering medicine, one-quarter of people with type 2 diabetes are not and it is likely that some of those would benefit from initiation of a blood-pressure lowering medicine.

Of people dispensed oral glucose-lowering medicines:

• 68% were dispensed an ACE inhibitor or an ARB
• 40% were dispensed another form of blood pressure-lowering medicine, i.e. a calcium channel blocker, thiazide diuretic or beta-blocker
• 25% were not dispensed any blood pressure-lowering medicines
• 68% were dispensed a statin

N.B. Medicines where there were two or more dispensings in 2018

Dispensing rates for these combinations of medicines were similar for people of European ethnicity, Māori and Pacific peoples. Most people (83%) who were dispensed calcium channel blockers, thiazide diuretics or beta blockers were also dispensed an ACE inhibitor or an ARB.

How many medicines are patients regularly prescribed?

Almost half of the patients dispensed an oral glucose-lowering medicines in New Zealand were dispensed five to nine long-term medicines^* in 2018. More than one-third of patients dispensed an oral glucose-lowering medicines were dispensed ten or more medicines long-term. Relatively high rates of co-morbidities, e.g. hypertension and other cardiovascular disease and gout, are expected in people with type 2 diabetes as the conditions share many risk factors, including increasing age.

^* Defined as two or more dispensings in 2018, including oral glucose-lowering medicines

For patients taking multiple medicines it may be appropriate to review:

• The original indications for prescribing a medicine and if they remain current or if the balance of risks and benefits has changed, e.g. proton pump inhibitors, anticholinergics, hypnotic medicines, bisphosphonates, medicines for chronic or neuropathic pain and medicines for mental health
• Adherence to the medicine regimen and whether this can be improved, e.g. by introducing smartphone reminders or pill boxes
• Whether a combination formulation could be used instead of two individual medicines, e.g. an ACE inhibitor/ARB + a diuretic or metformin + vildagliptin
• If patients prescribed three oral glucose-lowering medicines would benefit from insulin initiation
• The balance of risks and benefits for the current diabetes treatment regimen, e.g. is it appropriate to reduce the intensity of glycaemic control or cardiovascular management
• Whether medicines have been prescribed to manage the adverse effects of another medicine (also known as a prescribing cascade)

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