Screening for diabetes in asymptomatic adults

As part of CVD risk assessment, all adults should have an HbA1c performed in men from 45 years of age and women from 55 years of age with the frequency of follow up screening based on risk.

NB Start from 30 years in men and 40 years in women if Māori, Pacific or Indo-Asian ethnicity

Two abnormal tests (HbA1c or fasting) are required to confirm the diagnosis either on same day or subsequent test without delay

All patients with ‘prediabetes’ (HbA1c 41 – 49 mmol/mol or fasting glucose 6.1 – 6.9 mmol/L or 2 hour glucose on GTT 7.8 – 11 mmol/L) should have an HbA1c measured annually to determine if they have progressed to type 2 diabetes

Women with previous gestational diabetes should have an HbA1c measured annually to determine if they have progressed to type 2 diabetes

All patients aged > 18 years who are overweight or obese (e.g. BMI > 25 kg/m2 or > 23 kg/m2 if Asian ethnicity) with at least one other risk factor for diabetes should have an HbA1c performed at least every 3 years

Non-European ethnicity
Previous ‘prediabetes’ or T2D in remission
First degree relative with type 2 diabetes < 40 years of age
Clinical features of insulin resistance e.g. polycystic ovarian syndrome, acanthosis nigricans, hypertension, dyslipidaemia etc.
History of cardiovascular disease
Current long-term corticosteroid or antipsychotic therapy
Post transplant
Smoker

If the HbA1c is unreliable a fasting glucose or a 75 g oral glucose tolerance test should be performed

An HbA1c may be unreliable in:

Any haemoglobinopathy e.g. sickle cell anaemia, thalassemia
Altered red cell turnover e.g. bleeding, haemolysis, significant iron deficiency etc.
Post blood transfusion
Second and third trimesters of pregnancy

If fasting glucose is ≥ 7 mmol/L or 2 hour glucose is ≥ 11.1 mmol/L the patient has diabetes
If fasting glucose is < 7 mmol/L and 2 hour glucose is ≤ 11 mmol/L then repeat an HbA1c and fasting glucose in 3 months

If the repeat HbA1c is ≥ 50 mmol/L or fasting glucose is ≥ 7 mmol/L the patient has diabetes
If the repeat HbA1c is 41 - 49 mmol/mol and fasting glucose 6 - 6.9 mmol/L then treat as ‘prediabetes’

For guidance on how to screen for diabetes in children and youth please click here

References:

Alexia S Peña, Jacqueline A Curran, Michelle Fuery, Catherine George, Craig A Jefferies, Kristine Lobley, Karissa Ludwig, Ann M Maguire, Emily Papadimos, Aimee Peters, Fiona Sellars, Jane Speight, Angela Titmuss, Dyanne Wilson, Jencia Wong, Caroline Worth and Rachana Dahiya. Screening, assessment and management of type 2 diabetes mellitus in children and adolescents: Australasian Paediatric Endocrine Group (APEG) guidelines. MJA [Internet]. 2020;213(1). Available from: https://www.mja.com.au/journal/2020/213/1/screening-assessment-and-management-type-2-diabetes-mellitus-children-and

Type 2 Diabetes Management Guidelines

References: