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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.

• 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.