Screening for Diabetes

Type 2 diabetes screening is risk-based. In the general population, use AUSDRISK to identify people who need biochemical screening. Aboriginal and Torres Strait Islander adults are screened directly with blood testing rather than AUSDRISK.

  1. General population
    • From age 40 years, assess diabetes risk every 3 years using AUSDRISK.
    • AUSDRISK ≥12 = high risk → screen with fasting blood glucose (FBG) or HbA1c.
    • AUSDRISK estimates the risk of developing type 2 diabetes over the next 5 years.
  2. Screen directly if high risk
    • FBG or HbA1c every 3 years if any of:
      • overweight/obesity + age ≥40
      • overweight/obesity age 18–40 + hypertension or evidence of insulin resistance
      • first-degree relative with type 2 diabetes
      • previous cardiovascular event
      • previous gestational diabetes
      • PCOS
      • antipsychotic medication
      • higher-risk ethnicity, including South Asian, South-east Asian, Middle Eastern, North African, Māori or Pacific Islander background
      • AUSDRISK ≥12.
    • Do not wait for an AUSDRISK score if the patient already clearly belongs to a high-risk group.
  3. Aboriginal and Torres Strait Islander people
    • From age 18 years, screen opportunistically and/or annually.
    • Use:
      • FBG, or
      • HbA1c.
    • If results are equivocal, perform an OGTT.
    • Do not use AUSDRISK as the primary screening strategy.
    • BP, eGFR and uACR are important preventive assessments in this population, but they are not diabetes screening tests.
    • For expanded detail: ATSI Screening
  4. Interpreting screening
    • FBG <5.5 mmol/L → diabetes unlikely → repeat in 3 years if still indicated.
    • FBG 5.5–6.9 mmol/L → diabetes possible → OGTT.
    • HbA1c <6.0% (42 mmol/mol) → diabetes unlikely.
    • HbA1c 6.0–6.4% (42–46 mmol/mol) → increased risk → repeat in 12 months.
    • Impaired fasting glucose or impaired glucose tolerance → screen annually.
  5. Diagnosis of diabetes
    • FBG ≥7.0 mmol/L
    • 2-hour glucose ≥11.1 mmol/L on OGTT
    • HbA1c ≥6.5% (48 mmol/mol)
    • Random plasma glucose ≥11.1 mmol/L with classic symptoms.
    • In an asymptomatic patient, confirm an abnormal diagnostic result with a second concordant laboratory test, preferably repeating the same test on another day.
    • For expanded detail: Diabetes
  6. AUSDRISK
    • Key variables include:
      • age
      • sex
      • ethnicity
      • family history
      • previous high blood glucose
      • antihypertensive treatment
      • smoking
      • fruit and vegetable intake
      • physical activity
      • waist circumference.
    • Score:
      • ≤5 = low risk
      • 6–11 = intermediate risk
      • ≥12 = high risk.
    • AUSDRISK is a risk assessment tool, not a diagnostic test.
  7. Symptoms are not screening
    • Polyuria
    • polydipsia
    • unexplained weight loss
    • recurrent infections
    • symptoms of hyperglycaemia.
    • These require diagnostic testing, not routine risk screening.

The useful exam skeleton is:

  • ≥40 → AUSDRISK q3y
  • AUSDRISK ≥12 / high-risk condition → FBG or HbA1c q3y
  • Impaired glucose metabolism → yearly
  • ATSI ≥18 → FBG or HbA1c annually; no AUSDRISK
  • FBG 5.5–6.9 → OGTT
  • Diabetes = FBG ≥7 / 2-h ≥11.1 / HbA1c ≥6.5%
  • Asymptomatic abnormal result → confirm

Current Key Resources

ATSI ≥18 → FBG or HbA1c annually; no AUSDRISK