Is HbA1c Testing Worth It?
Fasting glucose captures a single morning. HbA1c captures the last 3 months. With 500,000 Australians walking around with undiagnosed diabetes, this no-fasting test might be your earliest warning.
500,000
Australians have undiagnosed type 2 diabetes—many discovered only after complications develop
Source: [1]
The Short Answer
Yes—especially if you're over 40 or have risk factors. HbA1c is guideline-backed (Tier 1), doesn't require fasting, and provides a 3-month metabolic picture that fasting glucose simply can't. With type 2 diabetes incidence having nearly halved since 2008 thanks to early detection and prevention, this is one test where catching prediabetes genuinely changes outcomes.
What Is HbA1c?
HbA1c (glycated haemoglobin) measures how much glucose has attached to your red blood cells over their 2-3 month lifespan. Glucose binds to haemoglobin—the oxygen-carrying protein in your blood—and stays attached until the red blood cell dies.
Think of it like this: fasting glucose tells you the weather today; HbA1c tells you the climate.
The Australian Diabetes Picture (2024)
- 1.3 million Australians living with diagnosed diabetes (5.1% of population)[1]
- 500,000+ estimated with undiagnosed type 2 diabetes[1]
- 2 million Australians with prediabetes—most unaware[2]
- 125 people newly diagnosed with type 2 diabetes every day[1]
- Good news: Type 2 diabetes incidence rates have almost halved since 2008[1]
Fasting Glucose vs HbA1c: The Comparison
Both tests have their place, but they answer different questions:
Fasting Glucose
- Single point in time
- Requires 8+ hours fasting
- Affected by stress, sleep, illness, meals
- Can miss prediabetes if testing on a 'good' day
- Cheaper, often first-line screening
HbA1c
- 2-3 month average
- No fasting required—any time of day
- Not affected by recent meals or stress
- Reveals patterns that single tests miss
- Correlates better with diabetes complications[3]
The Limitation
HbA1c can be affected by conditions that alter red blood cell lifespan: haemoglobin variants (common in some ethnic groups), kidney disease, recent blood transfusion, iron deficiency anaemia. Your GP will interpret results in context.[3]
Understanding Your Results
Australia uses both percentage (%) and mmol/mol units. Here's what the numbers mean:[2]
Blood sugar regulation is within healthy range. Retest in 3 years if no risk factors.
Higher than normal; 5-10% annual risk of progressing to diabetes without intervention. This is your window to act.
Suggests diabetes; requires confirmation testing and management plan from your GP.
Who Should Consider Testing?
The RACGP recommends diabetes screening every 3 years from age 40, or earlier with risk factors:[2]
| Risk Factor | Why It Matters |
|---|---|
| Age 40+ | Type 2 diabetes risk increases with age—screening recommended every 3 years |
| First-degree family history | Parent or sibling with diabetes doubles your risk |
| Overweight or obese | Particularly central adiposity (waist >94cm men, >80cm women) |
| Aboriginal or Torres Strait Islander | 3x higher diabetes prevalence—screening from age 18[1] |
| History of gestational diabetes | 50% lifetime risk of developing type 2 diabetes |
| Polycystic ovary syndrome (PCOS) | Strong association with insulin resistance |
| High blood pressure or dyslipidaemia | Often clusters with metabolic dysfunction |
| Previous impaired glucose result | Prior prediabetes or impaired fasting glucose |
The Prediabetes Window of Opportunity
Why Catching Prediabetes Matters
Prediabetes isn't a life sentence—it's a reversible warning sign. The evidence is compelling:[4][5]
- 58% reduction in progression to diabetes with lifestyle intervention (Diabetes Prevention Program)[4]
- 40-58% reversal rate to normal glucose with structured lifestyle changes[5]
- Each 1% weight loss reduces diabetes risk by approximately 16%
- 150 minutes/week of moderate exercise significantly improves insulin sensitivity
Small changes now prevent bigger interventions later. Once you have diabetes, you manage it. With prediabetes, you can reverse it.
AUSDRISK: Know Your Risk Score
Not sure if you should test? The Australian Type 2 Diabetes Risk Assessment Tool (AUSDRISK) gives you a 5-year risk estimate based on age, gender, ethnicity, family history, physical activity, and waist measurement.[6]
AUSDRISK Score Interpretation
- 5 or less: Low risk (~1 in 100 develop diabetes)
- 6-11: Intermediate risk (~1 in 30-50)
- 12+: High risk (~1 in 7-14)—book a GP visit
Who Should Complete It
- All adults 40-49 without known diabetes
- Younger adults with risk factors
- Aboriginal/Torres Strait Islander people 18+
- Anyone curious about their metabolic health
What to Expect from Your GP
Good news: HbA1c is a Tier 1 guideline-backed test with established clinical pathways. Your GP will know exactly what to do:[2]
- Normal result: Retest in 3 years (or sooner if risk factors develop)
- Prediabetes: Lifestyle counselling, possible dietitian referral, retest in 6-12 months
- Diabetes range: Confirmation test, management plan, HbA1c targets, medication discussion
- Medicare rebate: Covered when ordered by GP with clinical indication
Is It Worth the Cost?
✗ Probably Skip If...
- You tested in the last 12 months with normal results and no new risk factors
- You're under 40 with no risk factors and healthy weight
- You're already managing diagnosed diabetes (HbA1c is for screening, not monitoring—your GP handles that)
✓ Worth Considering If...
- Age 40+ and haven't screened in 3 years[2]
- You have risk factors (family history, overweight, PCOS, gestational diabetes)
- AUSDRISK score of 12 or higher[6]
- Symptoms: increased thirst, frequent urination, unexplained fatigue
- You want the convenience of no-fasting testing
The Bottom Line
HbA1c is one of the most actionable screening tests available.
Unlike tests where results can be ambiguous, HbA1c gives clear categories: normal, prediabetes, or diabetes range. Your GP knows exactly what to do with each result.
The real power is in catching prediabetes. With 58% of progression preventable through lifestyle changes, and type 2 diabetes incidence having nearly halved since 2008 thanks to better screening and prevention, HbA1c might be the test that changes your trajectory—if you catch it early enough.
No fasting required. No morning appointments. Just a clear picture of your metabolic health.
Frequently Asked Questions
Disclaimer:This information is educational only and not medical advice. Results should be interpreted by your health practitioner in the context of your symptoms and health history. Treatment decisions should be made with your doctor or specialist.