4727.0.55.002 - Australian Aboriginal and Torres Strait Islander Health Survey: Users' Guide, 2012-13

ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 10/09/2014 First Issue

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Contents >> Biomedical Measures >> Diabetes biomarkers

DIABETES BIOMARKERS

Diabetes is a chronic condition where insulin, a hormone that controls blood glucose levels, is no longer produced or not produced in sufficient amounts by the body.¹ If left undiagnosed or poorly managed, diabetes can lead to coronary heart disease, stroke, kidney failure, limb amputations or blindness. According to the 2003 Australian Burden of Disease Study, diabetes accounted for 9% of the disease burden in the Aboriginal and Torres Strait Islander population.²

The National Aboriginal and Torres Strait Islander Health Measures Survey (NATSIHMS) provides an objective measurement of the number of Aboriginal and Torres Strait Islander people with diabetes in Australia. It included two tests to measure diabetes: a fasting plasma glucose test and a glycated haemoglobin test (commonly referred to as HbA1c). Estimates of diabetes prevalence and management from the NATSIHMS were derived using a combination of blood tests, medication use (see AATSIHS pathology referral forms in the Downloads page of this product) and self reported information on diabetes from the National Aboriginal and Torres Strait Islander Health Survey (NATSIHS) and the National Aboriginal and Torres Strait Islander Nutrition and Physical Activity Survey (NATSINPAS). The biomedical results from the NATSIHMS can be used together with the self reported data to estimate disease prevalence rates. For details on self reported diabetes, see the relevant Diabetes Mellitus chapter in this product.

DIABETES PREVALENCE

Diabetes prevalence was derived using a combination of blood test results and self reported information on diabetes diagnosis and medication use.

A person was considered to have known diabetes if:

they had ever been told by a doctor or nurse that they have diabetes and they were taking diabetes medication (either insulin or tablets); OR
they had ever been told by a doctor or nurse that they have diabetes and their blood test result for fasting plasma glucose was greater than or equal to the cut off point for diabetes (that is, ≥7.0 mmol/L).

Note: people who had been told by a doctor or nurse that they have diabetes, but who were not taking medication for diabetes and did not have a fasting plasma glucose level ≥7.0 mmol/L, were classified as not having diabetes.

People with known diabetes were further classified as having Type I, Type II or Type unknown, based on the type of diabetes that a doctor or nurse told them they had. Women with gestational diabetes were excluded.

A person was considered to have newly diagnosed diabetes if they reported no prior diagnosis of diabetes but had a fasting plasma glucose value ≥7.0 mmol/L.

Total persons with diabetes was defined as the total number of persons with known diabetes and newly diagnosed diabetes.

A person was considered to be at high risk of diabetes if they did not currently have diabetes, but had an impaired fasting plasma glucose result, that is, a fasting plasma glucose level ranging from 6.1 mmol/L to less than 7.0 mmol/L.³

In the NATSIHMS, the following definitions were used for fasting plasma glucose levels and glycated haemogloblin (HbA1c) levels:

Cut off points for Diabetes in the NATSIHMS


	Fasting plasma glucose (FPG) (mmol/L)(a)	HbA1c (%)(b)

Has diabetes	≥7.0	≥6.5
At high risk of diabetes	6.1 to <7.0	6.0 to <6.5
No diabetes	<6.1	<6.0

(a) Based on World Health Organization cut off points for fasting plasma glucose.³
(b) An HbA1c level of greater than or equal to 6.5% is the WHO recommended cut off point for diabetes.⁴

The NATSIHMS diabetes classification outlined in Figure 1, illustrates how the combination of self reported diabetes data and diabetes test results has been used to define known diabetes, newly diagnosed diabetes, persons at high risk of having diabetes and persons who do not have diabetes.

Figure 1: 2012–13 NATSIHMS diabetes classification

* Cut-offs for diabetes test results are detailed in the table above.

DIABETES MANAGEMENT

In the NATSIHMS, information on diabetes management is presented for those with known diabetes. See Figure 1 above for information on how this population is defined.

Goals for optimum diabetes management, as defined by the 2014-15 General Practice Management of Type 2 Diabetes⁵, are as follows:

Fasting blood glucose levels between 6.0 to 8.0 mmol/L
HbA1c levels less than or equal to 7.0%
Total cholesterol less than 4.0 mmol/L
HDL 'good' cholesterol greater than or equal to 1.0 mmol/L
LDL 'bad' cholesterol less than 2.0 mmol/L
Non-HDL cholesterol less than 2.5 mmol/L
Triglycerides less than 2.0 mmol/L
Albumin creatinine ratio (a kidney function test) less than 3.5 mg/mmol for women and less than 2.5 mg/mmol for men
Urinary albumin excretion less than 20 mg/L
Blood pressure less than or equal to 130/80 mmHg
'Normal' Body Mass Index (i.e. a BMI score of between 18.5 and 24.9)*
Non-smoker
Normal healthy eating**
Alcohol intake less than or equal to 2 standard drinks per day**
At least 30 minutes of physical activity per day, most days of the week (total greater than or equal to 150 minutes per week)**
Immunisation against influenza, pneumococcal disease, diphtheria, tetanus, and pertussis**.

* The Guidelines do not specifically prescribe a normal BMI but rather a ‘healthy’ weight loss goal. Normal BMI is used for this data item as the survey only collected body mass at one time point. The previous guidelines (2012-13) also prescribed a normal BMI.
**Note information on normal eating habits, immunisation, alcohol and physical activity targets have not been included in this release, as data for these variables are not available for all persons in the NATSIHMS. However, some of this information can be sourced from the National Aboriginal and Torres Strait Islander Health Survey (NATSIHS) component.

Comparability with other surveys

The NATSIHMS is the first ABS Aboriginal and Torres Strait Islander survey to collect biomedical information. Given it was also the first national level survey (ABS or otherwise) to collect such data for the Aboriginal and Torres Strait Islander population, no comparisons with previous surveys for this population are possible.

However, biomedical data was also collected for all Australians in the 2011-12 National Health Measures Survey (NHMS) and information about comparisons between the NHMS results and those of non-ABS surveys is available from the Comparisons with other Australian surveys section of the Biomedical Results for Chronic Diseases, 2011-12 publication.

More information regarding the biomedical tests and cut off points can be found in the relevant subsections.

ENDNOTES

1 Diabetes Australia 2011, What is Diabetes?, <http://www.diabetesaustralia.com.au/en/Understanding-Diabetes/What-is-Diabetes/>, Last accessed 08/09/2014.
2 Vos T, Barker B, Stanley L, Lopez AD 2007. The Burden of Disease and Injury in Aboriginal and Torres Strait Islander peoples 2003, School of Population Health, The University of Queensland, Brisbane, <http://www.lowitja.org.au/sites/default/files/docs/Indigenous-BoD-Summary-Report_0.pdf>, Last accessed 08/09/2014.
3 World Health Organization 2006, Definition and diagnosis of diabetes mellitus and intermediate hyperglycemia, <http://www.who.int/diabetes/publications/Definition%20and%20diagnosis%20of%20diabetes_new.pdf>, Last accessed 08/09/2014.
4 World Health Organization 2011, Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus, <http://www.who.int/diabetes/publications/report-hba1c_2011.pdf>, Last accessed 08/09/2014.
5 Diabetes Australia, 2014, General practice management of type 2 diabetes – 2014–15. <http://www.diabetesaustralia.com.au/PageFiles/763/UPdated%20GP%20guidelines.pdf>, Last accessed 08/09/2014.

This section contains the following subsection :
Fasting plasma glucose
Glycated haemoglobin (HbA1c)