Guidelines for preventive activities in general practice

The Red Book
8.4 Type 2 diabetes
☰ Table of contents

Age range chart

0-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-79 >80

Aboriginal and Torres Strait Islander peoples

Age range chart

0-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-79 >80

Abnormal blood glucose is a modifiable risk factor for CVD and a diagnosis of diabetes substantially increases a person’s absolute CVD risk score. The Australian type 2 diabetes risk assesment tool (AUSDRISK) is useful in assessing risk of diabetes. Preventive interventions (refer to Table 8.4.3) have been shown to reduce progression to diabetes in patients with impaired fasting glucose.


Patients at high risk should be screened for diabetes every three years from 40 years of age. Aboriginal and Torres Strait Islander peoples should have their risk of diabetes assessed every three years from 18 years of age. Screening should be part of a comprehensive CVD assessment including BP, lipids, smoking, physical activity, diet, overweight and obesity.


Table 8.4.1. Type 2 diabetes: Identifying risk

Who is at risk?

What should be done?

How often?

Increased risk

  • ≥40 years of age
  • Aboriginal and Torres Strait Islander peoples aged ≥18 years


Every three years (III, C)

High risk

  • ≥40 years of age and being overweight or obese (refer to Section 7.2. Overweight)
  • AUSDRISK score of 12 or more
  • Consider screening the following groups because they may be at increased risk for diabetes at an earlier age or lower body mass index (BMI):
    • first-degree relative with diabetes
    • high-risk race/ethnicity (Indian subcontinent or Pacific Islanders)
    • all people with a history of a previous cardiovascular event (eg acute myocardial infarction or stroke)
    • women with a history of gestational diabetes mellitus
    • women with polycystic ovary syndrome
    • patients on antipsychotic drugs

Fasting blood glucose (III, B) 57–59 


glycated haemoglobin (HbA1c)

Every three years (III, C)

  • Those with impaired glucose tolerance test or impaired fasting glucose (not limited by age)

Fasting blood glucose (III, B) or HbA1c58

Every 12 months (III, C)

*The Australian type 2 diabetes risk assessment tool (AUSDRISK) 

BMI, body mass index; HbA1c, glycated haemoglobin


Table 8.4.2. Tests to detect diabetes*



Fasting blood glucose

Measure plasma glucose levels on a fasting sample: 58

  • <5.5 mmol/l: Diabetes unlikely
  • 5.5–6.9 mmol/L: May need to perform an oral glucose tolerance test
  • ≥7.0 mmol/L (>11.1 non-fasting): Diabetes likely; repeat fasting blood sugar on a separate day to confirm

The test should be performed on venous blood and tested in a laboratory to confirm a diagnosis 

Impaired fasting glucose is diagnosed on the basis of a result between 6.1 and 6.9 mmol/L

Glycated haemoglobin (HbA1c)

HbA1c may be used as a diagnostic test for diabetes. HbA1c of ≥48 mmol/mol (6.5%) is diagnostic of diabetes 60, 61

Oral glucose tolerance test

Measure the plasma glucose before (fasting) and two hours after a 75 g glucose load is taken orally. Diabetes is diagnosed if fasting plasma glucose is ≥7.0 mmol/L or two-hour plasma glucose is ≥11.1 mmol/L. If the two-hour plasma glucose is between 7.8 and 11.0 mmol/L, there is impaired glucose tolerance. A two-hour result <7.8 mmol/L is considered normal 58

*Cut off levels for classifications vary by national and World Health Organization (WHO) guidelines, and are subject to change as more evidence is developed 

HbA1c, glycated haemoglobin; WHO, World Health Organization


Table 8.4.3. Type 2 diabetes: Preventive interventions

Target group


Impaired glucose tolerance, impaired fasting glucose and those with an elevated Australian type 2 diabetes risk assesment tool (AUSDRISK) score or with other specific high-risk factors

  • Increasing physical activity (eg 30 minutes brisk walking five times a week) and/or weight loss reduces risk of developing diabetes by 40–60% in those at high risk 62–65
  • Give advice on healthy low-fat diet (<30% kcal or kilojoules from fat and <10% from saturated fat; high fibre, low glycaemic index with cereals, legumes, vegetables and fruits), weight loss and increased physical activity (refer to Smoking, nutrition, alcohol, physical activity (SNAP): A population health guide to behavioural risk factors in general practice, 2nd edn)
  • Refer patients to a dietitian and a physical activity program
  • Provide pre-conception advice to women with a history of gestational diabetes

AUSDRISK, Australian type 2 diabetes risk assessment tool

The RACGP and Diabetes Australia’s publication General practice management of type 2 diabetes – 2016–18 provides guidance for the management of patients diagnosed with T2D.


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