Diabetes single map PHO analysis Consumer summary (164KB, pdf)

The goal of this Atlas of Healthcare Variation domain is to investigate the quality of care given to people with diabetes. The data is not intended to form the basis for judgement or definitive statements of quality, rather to raise questions about potential areas for quality improvement. The indicators were developed with the assistance of an expert advisory group. 

Update to include 2018 data

(Data updated December 2019)

This Atlas domain has been updated using data from the updated Virtual Diabetes Register (VDR) for 2018.

Key messages

  • It is estimated that 253,000 people had diabetes in 2018, an increase from 245,000 people in 2017 and 241,000 in 2016. In 2018, age-specific rates of diabetes prevalence varied more than two-fold by DHB, from between 9 percent and 25 percent of a DHB population aged 65–74 years. Prevalence varies by ethnicity, with Pacific peoples of all ages experiencing the highest rate.
  • The regular use of medicines for glycaemic control (insulin or metformin) varied 1.4-fold by DHB, from between 49 percent and 69 percent of those with diabetes regularly receiving those medicines in 2018.
  • The percentage of bed-days occupied by people with diabetes increased with age. There was a peak in the 65–74-year age group and the differences between ethnicities are highlighted; for example, 49 percent of bed-days were occupied by Pacific peoples compared with European/other at 20 percent.

Key findings

Diabetes prevalence is markedly higher in some population subgroups than in others

The prevalence of diabetes increased significantly with age, from a mean of 0.3 percent in those aged 0–24 years to 17 percent in those aged 75 years and older. In 2018, diabetes prevalence varied two fold by DHB, from 9–25 percent of a DHB population aged 65–74 years and more than three-fold in those aged 45–64 years (4–15 percent).

Pacific peoples had a significantly higher prevalence of diabetes than all other ethnic groups, while those identifying as European/other had a significantly lower rate. People of Indo-Asian ethnicity are not presented separately here; however, rates of diabetes in this population are close to those observed in Pacific peoples.

Good glycaemic control and cardiovascular risk factor management are important for positive outcomes

If haemoglobin A1c (HbA1c) does not meet an agreed target with dietary and lifestyle changes, drug therapy is recommended. Insulin and metformin are well proven. Evidence suggests good glycaemic control benefits microvascular outcomes.[1] The provision of comprehensive cardiovascular risk management for people with diabetes (such as blood pressure and lipid management) has been shown to improve macrovascular outcomes substantially while good glycaemic control has a smaller and very delayed effect.

Insulin and metformin use varied

Given both the lack of available data on clinical parameters and the inability to split data by diabetes type, the indicators of medication use are not intended to suggest an ‘ideal’ rate of use, rather they provide a high-level view. Wide variation may raise questions such as, do DHBs with lower-than-average rates of medication use have lower or higher rates of diabetes complications?

Without HbA1c results available, nationally, 59 percent of people with diabetes aged 25 years and over regularly received insulin and/or metformin, with use highest in those aged 65–74 years. This varied 1.4-fold by DHB for all ages (49–69 percent).

Metformin remains the standard initial drug treatment for type 2 diabetes. As expected, use increased with age. On average, 28 percent of people with diabetes aged 25–44 years regularly received metformin compared with 58 percent of those aged 65–74 years.

Overall, 23 percent of people with diabetes regularly received insulin. On average, European/other people had the highest rate of insulin dispensing (26 percent) compared with Asian people (13 percent). As might be expected, insulin use was highest in the 0–24-year age group with diabetes, with 62 percent of these regularly dispensed insulin.

Intensive management of high blood pressure and microalbuminuria

We have identified a technical error whereby one angiotensin-converting enzyme (ACE) inhibitor (cilazapril hydrochlorothiazide) was not included in the Atlas in 2014–17. As expected, its inclusion has increased the percentage of people receiving an ACE inhibitor or angiotensin II receptor blocker (ARB) across all years by around 5 percent. The relative differences between age and ethnic groups have stayed consistent with this change.

On average, 53 percent of people with diabetes received angiotensin-converting enzyme inhibitor (ACEI) or ARB medicines in 2018. This is a reduction from 55 percent in 2014. This varied 1.2-fold by DHB (49–59 percent. People of Asian ethnicity received the least ACEI or ARB medicines compared with all other ethnic groups.

Intensive management of blood pressure and microalbuminuria is recommended to prevent progression of renal disease in diabetes. ACEI and ARB medicines are first-line treatments.

The younger the age at diagnosis, the greater the impact of diabetes on life expectancy, highlighting the importance of glycaemic control, blood pressure management and prevention of kidney disease in younger people with diabetes.

Māori and Pacific peoples have a higher rate of ACEI or ARB medicine use at a younger age, however some data also shows these populations have significantly higher rates of end-stage renal disease. A recent publication found Māori and Pacific peoples have a relative risk of 6.48 for developing end-stage renal disease due to type 2 diabetes compared with other New Zealanders.[2]

Complications – admissions for diabetic ketoacidosis and hypoglycaemia varied by age

Nationally, the rate of admissions to hospital for diabetic ketoacidosis were eight-fold higher in those aged 0–24 years than in all other age groups. Similarly, the rate of admissions as a result of hypoglycaemia was highest in this youngest age group although the count of people was highest in those aged 65 years and over. The numbers in each age group were too low to report by DHB.

Complications – lower-limb amputations increased with age

Lower-limb amputation rates increased significantly with age, with 94 percent occurring in those aged 45 years and over. While this rare complication affected only 0.21 percent of the diabetes population in a year, in 2018 this meant 540 people lost part of a lower limb as a result of their diabetes.

Note this indicator counts people with diabetes who had one or more amputations in a year. The VDR is a register so people who died during the year are excluded. This means that people who had an amputation during the year and died are not included here. The data is available on request: data-enquiries@moh.govt.nz.

People with diabetes occupied more bed-days for any reason

The number of medical and surgical bed-days occupied by people with diabetes was compared with the total occupied medical and surgical bed-days. Age had a significant effect on occupied bed-days. In 2018, age-specific rates varied over 2-fold. For example, people with diabetes aged 45–64 years occupied 23 percent of total bed-days, compared with a population prevalence of 8.3 percent of people with diabetes in this age group.

On an unadjusted basis, people with diabetes occupied 18.3 percent of total bed-days, despite a population prevalence of diabetes of 5.2 percent. However, some of the differences here are partially explained by the fact that increasing age is strongly associated with bed-day use and the age structure of people with diabetes is older than the general population. However, the extent of the bed occupancy remains large.

People of Māori, Pacific and Asian ethnicities with diabetes occupied significantly more bed-days than those in the European/other ethnic group – 26 percent on average compared with 15 percent.

Regular laboratory testing was lowest for screening renal disease (ACR)

We analysed rates for people with diabetes who received one or more laboratory tests in a year for HbA1c, albumin; creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR). On average, 88 percent received an HbA1c test, 67 percent an ACR test and 85 percent an eGFR test.

Rates differed by ethnicity for certain tests. In ACR testing, European/other and Māori received 64 percent on average compared with Asian and Pacific peoples, who received 74 percent on average.

Table 1 shows the percentage of people with diabetes receiving all three tests by age and ethnic group (2018).

Table 1: Percentage of people with diabetes receiving all three tests for HbA1c, ACR and eGFR, by age and ethnic group, New Zealand, 2018

Ethnic group Age group (years) (%)
25–44 45–64 65–74 75+ Total
Māori 49.7 63.4 68.2 62.3  61.0
Pacific peoples 59.6 75.3 77.5 69.0 71.9
Asian 59.4 77.2 77.8 70.2 73.3
European/other 47.7 62.7 68.6 60.4 61.7
Total 52.9 67.5 70.9 62.1 64.7

Questions raised:

  • How many of these results can be explained by the predominant type of diabetes?
  • Are rates for specific indicators lower or higher than might be expected?
  • Is there room for improvement in any of the indicators?
  • Do results reflect local differences in care?

Method and data source

This domain draws on data contained in the VDR, which was developed by the Ministry of Health to estimate and track the number of people diagnosed with diabetes.

The VDR combines and filters various sources of health information, including the National Minimum Dataset, the National Non-admitted Patients Collection (outpatients), the Pharmaceutical Collection, the Laboratory Claims Collection and the Primary Health Organisation Enrolment Collection.

The VDR was used to estimate the prevalence of diabetes. The data is based on health service utilisation data that is consistent with diabetes care rather than formal clinical diagnosis or laboratory results, so should be interpreted with some caution. The Atlas does not use any patient-identifiable data.

Download the methodology document (151KB, pdf).

Limitations

The Pharmaceutical Collection contains claim and payment information from community pharmacists for subsidised dispensing. This collection does not indicate whether a medicine was taken or whether the dose was effective. Over-the-counter medicines are not included.

In selecting indicators for oral hypoglycaemic medication use, the expert advisory group decided to focus only on metformin, as the first-line agent for people with type 2 diabetes and insulin as the key medication for people with type 1 diabetes. There is no ideal rate of medicine use in people with diabetes because it depends on clinical need. However, wide variation between DHBs or ethnic groups raises questions as to why the rate of medicine use varies.

The Laboratory Claims Collection includes tests performed in the community. The exclusion of hospital and point-of-care tests will under-count testing and may affect results more in some DHBs than in others.

Analysis does not split by type of diabetes

There were some limitations as to what measures could be presented. It was not possible to reliably split people by type of diabetes; hence the indicators represent a combination of those with type 1 and type 2 diabetes. Generally, most people with diabetes aged 0–24 years will have type 1 diabetes, while around 90 percent and over of those aged 25 years and above are expected to have type 2 diabetes.

The method used in the VDR to identify people with diabetes is less accurate at identifying children than adults with diabetes. A recently published survey highlights that local DHB data may be a better source for identifying prevalence in children.[3] More work is in hand in this area.

Some important outcome indicators could not be included

Due to limitations in currently available data we could not explore certain outcome indicators, including screening for diabetic retinopathy, retinopathy rates and end-stage renal failure. Outcome indicators, including myocardial infarction rates, stroke and other cardiovascular outcomes, are not included in this iteration of the diabetes Atlas domain, but are likely to be included in future updates. We encourage users to investigate local data in relation to these outcomes to promote improvement and equity initiatives at primary health organisation and practice level.

Relationship with other Ministry of Health activities

The diabetes Atlas domain links with the current (2015–20) strategy for diabetes, Living Well with Diabetes,[4] which provides an overall package of measures to improve care for people with diabetes in New Zealand. This includes work towards each DHB meeting the 20 quality standards published in 2014 (with an accompanying toolkit).[5] The standards link with many of the measures presented in the diabetes Atlas domain, so the two are complementary.

Recommended reading/suggested links


References

  1. Ministry of Health. 2018. Cardiovascular Disease Risk Assessment and Management for Primary Care. Wellington: Ministry of Health.
  2. Hill K, Ward P, Grace BS, et al. 2017. Social disparities in the prevalence of diabetes in Australia and in the development of end stage renal disease due to diabetes for Aboriginal and Torres Strait Islanders in Australia and Maori and Pacific Islanders in New Zealand. BMC Public Health 17(1): 802.
  3. Jefferies C, Owens N, Wiltshire E for the Clinical Network for Children with Diabetes in New Zealand, on behalf of the Paediatric Society of New Zealand diabetes clinical network. 2015. Care for children and adolescents with diabetes in New Zealand District Health Boards: Is the clinical resourcing ready for the challenge? NZMJ 128 (1424): 20–7.
  4. Ministry of Health. 2015. Living Well with Diabetes: A plan for people at high risk of or living with diabetes 2015–2020. Wellington: Ministry of Health.
  5. Ministry of Health. 2014. Quality Standards for Diabetes Care Toolkit. Wellington: Ministry of Health.

Last updated 19/03/2020