FASTING PLASMA GLUCOSE
Definition
Plasma glucose, in simple terms, is sugar in the blood. Plasma glucose is converted into energy in the body by a hormone called insulin. However, people with diabetes do not produce sufficient insulin, therefore plasma glucose is not converted into energy, which causes high blood sugar levels (glycemia). High levels of fasting plasma glucose may increase the risk of diabetes.
The fasting plasma glucose test measures the amount of glucose (sugar) circulating in the blood at the time of the test.
Population
Fasting plasma glucose test results were obtained for persons aged 18 years and over, who agreed to participate in the National Aboriginal and Torres Strait Islander Health Measures Survey (NATSIHMS) and who fasted for 8 hours or more, prior to providing a blood sample.
Methodology
A blood sample was collected from participants and fasting plasma glucose levels were measured at the Douglass Hanly Moir (DHM) laboratory.
In the NATSIHMS cut off reference values for normal and abnormal results were sourced from the World Health Organization (WHO) guidelines.1 These guidelines are based on epidemiological data and publications of major clinical trials.
In the NATSIHMS, the following definitions were used for fasting plasma glucose:
- Normal fasting plasma glucose levels < 6.1 mmol/L indicates a person does not have diabetes
- Fasting plasma glucose levels between 6.1 to < 7.0 mmol/L indicates a person is at high risk of having diabetes
- Abnormal fasting blood glucose levels ≥ 7.0 mmol/L indicates a person has diabetes.
In the NATSIHMS, the fasting plasma glucose results, in addition to the self reported data on diabetes, were used to estimate the prevalence of diabetes and information on diabetes management in Australia. Information about the definitions for measuring diabetes is available from the
Diabetes biomarkers page of this chapter.
Further test information about the analysis method and machine used to measure fasting plasma glucose levels is available in Excel spreadsheet format in the
Downloads page of this product.
Data items
The data items and related output categories for this topic are available in Excel spreadsheet format from the
Downloads page of this product.
Interpretation
Points to be considered when interpreting data for this topic include the following:
- Fasting plasma glucose results do not confirm a specific diagnosis without consultation with a health professional.
- It should be noted that the fasting plasma glucose results, on their own, do not satisfy the definition of diabetes in the NATSIHMS. Information about the definitions for measuring diabetes is available from the Diabetes biomarkers topic page of this chapter.
- Other studies have reported fasting plasma glucose test results using 2 hour fasting blood samples. As a result, the data should be interpreted with care.
- In the NATSIHMS, fasting plasma glucose results were not collected using the Oral Glucose Tolerance Test (OGTT). According to WHO, without this measurement, Impaired Fasting Glucose (IFG) or Impaired Glucose Tolerance (IGT) cannot be accurately determined. 1
- There are a number of different test methods for measuring fasting plasma glucose, which may produce different results. The data from this topic should therefore be used with caution when comparing fasting plasma glucose results from other studies using a different test method or equation.
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.
ENDNOTES
1 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.