Incidence of diabetes

Why is this an important indicator for diabetes?

This indicator shows the number of new cases (incidence) of insulin-treated diabetes and new cases of gestational diabetes mellitus (GDM) in Australia over time. The number of new cases of diabetes helps to predict future need for health services and to measure the success of prevention programs.

What are the results?

Insulin-treated diabetes in Australia

• Over 222,500 people began using insulin to treat their diabetes between 2000 and 2009. Most of these people (77%) had Type 2 diabetes (Table 1, Figure 1).
• The incidence of insulin-treated Type 2 diabetes rose from 74 per 100,000 people aged 10 or over in 2000, to 117 per 100,000 people aged 10 or over in 2009.
• New cases of Type 1 diabetes among children aged 0–14 increased from 19 per 100,000 children in 2000 to 25 per 100,000 children in 2004, but since 2004 the rate of new cases has remained relatively stable.
• From 2000 to 2009 there were 13,756 new cases of Type 1 diabetes among persons aged 15 and over, which equates to an average annual rate of 9 new cases per 100,000 population.
• From 2000 to 2009, the average annual incidence rate of Type 1 diabetes was 11.5 new cases per 100,000 population.

(a) Average rate for ten years from 2000 to 2009, directly age-standardised to the 2001 Australian population.
(b)Total includes gestational diabetes mellitus and 'other' cases of diabetes.

Source: 2009 National Diabetes Register (data extracted 2012).

For more information, see Incidence of insulin-treated diabetes in Australia 2000–2009.

Gestational diabetes mellitus (GDM)

• In 2009–10, over 13,600 separations for women aged 15–49 who gave birth as admitted patients in hospital had a diagnosis of GDM. In 43% of these separations, the women were being treated with insulin.
• New cases of GDM recorded in hospital separations for women aged 15–49 who gave birth rose by 21% between 2000–01 and 2009–10—from 3.6% to 4.4%.

What are the data sources?

There are three main data sources for this indicator:

• The National Diabetes Register (NDR)
• The National Hospital Morbidity Database (NHMD), and
• The 2001 ABS Estimated Resident Population (ERP).

The National Diabetes Register (NDR) holds data on new cases of insulin-treated diabetes of all types. The NDR includes only those with diabetes who agree to be included in the register.

Data for gestational diabetes were extracted from the National Hospital Morbidity Database (NHMD), which includes new cases of gestational diabetes (both insulin- and non-insulin-treated).

How is this indicator calculated?

All comparisons of diabetes incidence over time are age-standardised to the 2001 ABS ERP.

The overall incidence rates compare:

• numerator: the number of new cases of insulin-treated diabetes (from the NDR), to
• denominator: the total Australian population (from the 2001 ABS ERP).

The incidence rate of GDM compares:

• numerator: the number of separations with an outcome of delivery code (ICD-10-AM, Z37) and a principal diagnosis of gestational diabetes (O24.41, O24.42 and O24.49 in ICD-10-AM 2nd–5th editions; O24.42, O24.43, O24.44 and O24.49 in ICD-10-AM 6th edition). For this indicator, the following care types were excluded: newborn–unqualified days only, organ procurement–posthumous and hospital boarder.
• denominator: the number of separations for women giving birth in hospital (from the NHMD).

Are there any data limitations?

• Due to problems with the quality of the data on gestational diabetes, there were no analyses for gestational diabetes undertaken with the 2009 National Diabetes Register. We expect that information on these cases may be included in future reports.
• The overall incidence rate of Type 2 diabetes in Australia for people not requiring insulin treatment cannot be estimated with accuracy due to gaps in the data currently available.
• In the period reported there was a change in how diabetes was defined. ‘Type 1’, ‘Type 2’ and ‘other types’ of diabetes replaced the older terms ‘insulin-dependent diabetes’ (IDDM) and ‘non-insulin-dependent diabetes’ (NIDDM). Analysis of data from the NDR has taken this into account.
• In the future, this indicator may also report new cases among different population groups, but current data are not complete enough for this.

Definitions

Incidence of diabetes is the number of new cases of diabetes during a given period.

Incidence rate of diabetes compares the number of new cases of diabetes to a total population.

Gestational diabetes mellitus is a form of diabetes that is defined as glucose intolerance in pregnant women not previously diagnosed with diabetes.

Where can I find more information?

AIHW 2012. Incidence of Insulin-treated diabetes in Australia 2000–2009.

AIHW 2007. National indicators for monitoring diabetes: report of the Diabetes Indicators Review Subcommittee of the National Diabetes Data Working Group. Diabetes series no. 6. Cat. no. CVD 38. Canberra: AIHW.

Abbreviations

ABS

Australian Bureau of Statistics

AIHW

Australian Institute of Health and Welfare

ERP

Estimated Resident Population

GDM

Gestational diabetes mellitus

ICD-10-AM

International Classification of Diseases, Tenth Revision, Australian Modification

IDDM

Insulin-dependent diabetes

NDR

National Diabetes Register

NHMD

National Hospital Morbidity Database

NIDDM

Non-insulin-dependent diabetes

Source data

(a) Average rate for ten years from 2000 to 2009, directly-age standardised to the 2001 Australian population.

Note: Age-standardised to the 2001 Australian population.
Source: 2009 National Diabetes Register (data extracted 2012).