Type 1 diabetes prevalence

Thank you for your request which was transferred in part to Pharmac on 9 April 2024 under the Official Information Act 1982 (the Act). You requested:

What population figures or estimates have been used in assessing Type 1 diabetes treatment worthiness for investment, and how these have been verified as accurate figures to test against

Background

In 2023, Pharmac completed its assessment of a funding proposal for continuous glucose monitors (CGMs). A public consultation was published on this proposal in March 2024.

As part of the budgetary impact assessment of this funding proposal, Pharmac staff estimated the size of the population with type 1 diabetes (T1D) and other types of pancreatic insufficiency.

You can find additional detail on these population estimates below.

Eligible population

The proposed Special Authority criteria for CGMs would enable funded access to all eligible people with T1D, people with cystic-fibrosis related diabetes, and people who have undergone a pancreatectomy.

Across these three groups, it is estimated that there would be an eligible population of at least 17,000 individuals in the first year of funding (2024).

The size of the eligible population was estimated using the Virtual Diabetes Register (VDR) by querying the database for a count of individuals who were resident in New Zealand and had health resource utilisation patterns consistent with pancreatic insufficiency (a sign of T1D), which include:

• attendance at outpatient services for diabetes-related retinal screening or diabetes management
• frequent laboratory tests for HbA1c and urinary albumin to creatinine ratio
• Initiation of publicly funded insulin therapy within one year of diagnosis.

The results of this query of the VDR, for the years 2016 to 2021, are outlined in the table below. Note these figures are expected to include people with cystic-fibrosis related diabetes and people who have undergone a pancreatectomy as well as T1D. These numbers are uncertain as not all people accessing services for pancreatic insufficiency may have definite T1D diagnoses.

Table 1 - Estimated number of individuals with pancreatic insufficiency between 2016 and 2021

The estimated number of people in New Zealand with pancreatic insufficiency is increasing, as seen in Table 1. The annual change in the number of individuals with pancreatic insufficiency was +0.40% in 2013, and this steadily increased to 2.53% in 2021. Pharmac assumed an increasing growth rate in the population over the next five years. The growth rate is estimated to be between 3% and 5% during the five years of listing. It is therefore expected that the eligible population could be as high as 21,000 individuals in Year 5. This is outlined below.

Table 2 - Estimated eligible population for CGMs over the first five years of listing

Finally, it has been assumed that the number of individuals who choose to be treated with CGMs is expected to be less than the eligible population presented in Table 2, since not all people who are eligible may take up CGMs.

Verification of estimate

The estimated number of people who may use CGMs in the proposed indication cannot be entirely verified until CGMs are funded and Pharmac can observe the number of people who take up CGMs.

However, in estimating the number of people eligible for CGMs, Pharmac identified that it is commonly considered that approximately 10% of people with diabetes have T1D (>24,000 people in 2013) (Ministry of Health, Quality Standards for Diabetes Care Toolkit: Standard 17. p179-189(external link)). The population with Type 2 diabetes is growing even more rapidly than the group with Type 1 diabetes, with 300,000 people with diabetes of any kind in 2022 (Te Whatu Ora, VDR 2022, https://www.tewhatuora.govt.nz/our-health-system/data-and-statistics/virtual-diabetes-tool/(external link)). Hence, Pharmac considers that 30,000 people (10% of 300,000) would be an over-estimate in NZ now.

Closing

We trust that this information answers your queries. Please note, you have the right to make a complaint to the Ombudsman about our response to your OIA, under section 28(3) of the OIA. Details of how to make a complaint(external link) are on the Ombudsman’s website. To make information more freely available, we publish selected OIA responses (excluding personal details) on our website. Please get in touch with us if you have any questions about this.