Type 1 diabetes

How many people are living with type 1 diabetes in Australia?

There are currently no accurate national data on the total number of cases (prevalence) of type 1 diabetes at all ages. However, the National (insulin-treated) Diabetes Register (NDR) can provide reliable estimates for children and young adults.

According to the NDR, around 13,000 children and young adults aged 0–19 had type 1 diabetes in 2020 (207 per 100,000 population).

Variation by age and sex

In 2020:

  • the prevalence of type 1 diabetes was similar among males and females
  • 81% of children and young adults with type 1 diabetes were aged 10–19, with prevalence rates around 15 times as high in children and young adults aged 15–19 as those aged 0–4 (406 and 27 per 100,000, respectively) (Figure 1).

Figure 1: Prevalence of type 1 diabetes in children and young adults, by age and sex, 2020

The bar chart shows the prevalence of type 1 diabetes in children and young adults by sex in 2020. Rates were highest among males and females aged 15–19 (411 and 401 per 100,000 population).

Trends over time

The age-standardised prevalence rates for type 1 diabetes among children and young adults remained stable between 2014 and 2020 (Figure 2).

Figure 2: Prevalence of type 1 diabetes in children and young adults, by sex, 2014–2020

The line chart shows the age-standardised rates of young males and females living with type 1 diabetes between 2014 to 2020. Across the years, rates have remained very stable from 213 to 211 per 100,000 population for males, and from 206 to 212 for females.

Variation between population groups

Aboriginal and Torres Strait Islander people

In 2020, there were 150 cases of type 1 diabetes (per 100,000 population) among Aboriginal and Torres Strait Islander children and young adults aged 0–19.

After adjusting for differences in the age structure of the populations, Indigenous children and young adults were around 20% less likely to be living with type 1 diabetes as their non-Indigenous counterparts (Figure 3).

Socioeconomic area

The prevalence of type 1 diabetes among children and young adults fluctuated across socioeconomic areas in 2020, with rates being 1.2 times higher among those living in the most disadvantaged areas compared to the least disadvantaged areas (Figure 3).

Remoteness area

There was no clear association between the prevalence of type 1 diabetes among children and young adults and remoteness area in 2020. Overall, rates were higher in Inner regional and Outer regional areas compared with Major cities and Remote and very remote areas (Figure 3).

Figure 3: Prevalence of type 1 diabetes in children and young adults, by selected population group and sex, 2020

The horizontal bar chart shows that male and female type 1 diabetes prevalence rates in 2020, were lower among younger Indigenous Australians, younger people living in inner regional areas, and younger people living in the second lowest socioeconomic areas.

Country of birth

Type 1 diabetes prevalence rates among children and young adults varied by country of birth. In 2020, after adjusting for differences in the age structure of the populations, rates were 1.8 times as high among people born in North-West Europe as people born in Australia (Figure 4). Caution should be used when interpreting these data due to a high level of missing country of birth information for people on the linked NDSS and APEG data.

Figure 4: Prevalence of type 1 diabetes in children and young adults, by country of birth, 2020

The horizontal bar chart shows that type 1 diabetes prevalence rates were highest among children and young adults born in North-West Europe and where were 1.8 times as high among people born Australia (270 and 153 per 100,000 population).

 

Why is prevalence only reported for children and young adults with type 1 diabetes?

The NDSS registration forms and database have changed over time.

  • Information recorded for older registrants is frequently incomplete for important variables, including diagnosis date and the date of first insulin use.
  • The largest change occurred progressively between 2 December 2002 and 28 February 2003. At this time, the clinical terminology used to describe diabetes type was updated from juvenile-onset diabetes, Insulin Dependent Diabetes Mellitus (IDDM) and Non-Insulin Dependent Diabetes Mellitus (NIDDM), to type 1 and type 2 diabetes. Prior to this, people registering with the NDSS with insulin-treated type 2 diabetes may have been incorrectly recorded as type 1 so that their insulin using needs could be met. This occurred because the NDSS registration form did not have an option for insulin-treated type 2 diabetes, reflecting diabetes classification at that time. All registrants that were classified as IDDM were reclassified as type 1 diabetes as there was no effective way to differentiate between diabetes types, resulting in misclassification for some people with insulin-treated type 2 diabetes.
  • In 2015, Diabetes Australia commissioned the Australian Healthcare Associates (AHA) to conduct an audit to test the reliability of the NDSS database and determine whether diabetes type is correctly recorded. Almost 1 in 5 (17.9%) of people surveyed with reported type 1 diabetes were found to have type 2 diabetes (25 of 140), with 80% of these people initially registered prior to 2003 (20 of 25) (AHA 2015). Small numbers of individuals with reported type 2 diabetes were also found to be misclassified (23 of 695).  Extrapolating these results to the 2020 NDSS data would suggest that over 21,000 registrants with reported type 1 diabetes are potentially misclassified.
  • The NDR uses NDSS data linked with the Australasian Paediatric Endocrine Group (APEG) state-based registries which is used as a secondary ascertainment dataset and a rigorous algorithm is applied to confirm diabetes type. The algorithm checks age at diagnosis and the period between diagnosis and first insulin use. These factors are important for confirming type 1 diabetes status due to younger diagnosis age and immediate requirement for insulin therapy for survival in type 1 diabetes. The validation undertaken for the NDR, as well as the use of a secondary ascertainment data source, provide confidence in the accuracy of diabetes type for younger Australian’s.
  • The Australian Bureau of Statistics National Health Survey also provides national estimates for type 1 diabetes. However, small numbers for younger age groups results in high variability and limits the reporting that is possible on people living with type 1 diabetes. Further, survey questions relating to diabetes include ‘Diabetes - type 1 - (insulin dependent)’ as the type 1 diabetes option, which may result in incorrect selection for people with type 2 diabetes using insulin.

How many people are newly diagnosed with type 1 diabetes in Australia?

Around 55,400 people were newly diagnosed with type 1 diabetes between 2000 and 2020 according to the National (insulin-treated) Diabetes Register (NDR). This was around 2,770 new cases of type 1 diabetes each year – an average of 8 new diagnoses a day.

There were 3,100 people newly diagnosed (incidence) with type 1 diabetes in Australia in 2020, equating to 12 diagnoses per 100,000 population.

Variation by age and sex

In 2020:

  • 65% of people newly diagnosed with type 1 diabetes were aged 0–29
  • the peak age group of diagnosis was 10–14 (37 and 34 per 100,000 for males and females, respectively) – more than 2 times the rate at ages 20–24 (17 and 12 per 100,000 for males and females, respectively) (Figure 5)
  • after adjusting for differences in the age structure of the populations, type 1 diabetes incidence rates were 1.4 times higher among males than females.

Figure 5: Incidence of type 1 diabetes, by age and sex, 2020

The butterfly chart shows the incidence rates of type 1 diabetes by age group in 2020. Rates were highest among males and females aged 10–14 years (37 and 34 per 100,000 population).

Trends over time

Type 1 diabetes incidence rates have remained relatively stable over the last 2 decades (Figure 6).

Figure 6: Incidence of type 1 diabetes, by sex, 2000–2020

The line chart shows the age-standardised incidence rates of male and female newly diagnosed with type 1 diabetes between 2000 to 2020. Over the last two decades, incidence rates have remained relatively stable, fluctuating between 13 and 15 new cases per 100,000 population for males and 10 to 11 new cases for females.

Variation between population groups

Aboriginal and Torres Strait Islander people

There were 164 Aboriginal and Torres Strait Islander people newly diagnosed with type 1 diabetes in 2020 (19 per 100,000 population). Age-standardised incidence rates were 1.8 times as high among Indigenous males compared with females.

After adjusting for differences in the age structure of the populations, the incidence rate was 1.4 times higher among Indigenous Australians compared with non-Indigenous Australians (Figure 7).

Socioeconomic area

The incidence of type 1 diabetes in 2020 was slightly lower in the least disadvantaged socioeconomic areas, but similar across the other areas (Figure 7).

Remoteness area

Type 1 diabetes incidence rates were slightly lower in Remote and very remote areas in 2020 than other areas (Figure 7).

Figure 7: Incidence of type 1 diabetes, by selected population groups and sex, 2020

The horizontal bar chart shows that male and female type 1 diabetes prevalence rates in 2020, were higher among Indigenous Australians, people living in inner and outer regional areas, and people living in the lowest socioeconomic areas.

Reference

Australian Healthcare Associates (AHA) (2015) NDSS Registrant Details Audit Final Report for Diabetes Australia, AHA, Melbourne.