Fasting glucose is a blood test that measures plasma glucose after 8 to 12 hours without food, reflecting overnight liver glucose output and how well insulin restrains it. Practitioners use it to screen for impaired fasting glucose and to read alongside fasting insulin. An incomplete fast, a sample left too long before processing, or poor sleep and illness beforehand can shift the result.
| Test type | Measured in a blood sample |
|---|---|
| Measurements required | Fasting Glucose only |
| Sample and collection | Fasting blood draw at a collection centre |
| Preparation | Fast for 8 to 12 hours before a morning collection, water only. |
| Turnaround | 3 to 5 business days |
| Available through | Diabetes & Glycaemic Studies, part of the Baseline Health Check. Also in: Full Body Health Check, Metabolic Panel. |
| Pricing | Included in the $99 Baseline Health Check |
| Results | Returned in the Vively practitioner platform, beside your client's other markers |
What are the Fasting Glucose reference and optimal ranges?
| Typical lab reference | Vively optimal | |
|---|---|---|
| Adults | 3.4 to 5.4 mmol/L | No separate optimal range. We read it against fasting insulin, HbA1c and the trend. |
| Adults, Australian diagnostic cut-offs | 6.1 to 6.9 mmol/L impaired fasting glucose; 7.0 mmol/L or above diabetes range (doctor confirms) | Not applicable |
Labs set their own reference range, so read the result against the range on the client's report (RCPA). The 6.1 and 7.0 mmol/L figures are diagnostic cut-offs a doctor confirms; the 3.4 to 5.4 mmol/L lab range flags results earlier.
Check a client's Fasting Glucose result
Enter the value from your client's lab report to see where it sits against the typical lab range and the Vively optimal range.
A guide only, not a diagnosis. One result is a starting point: read it with symptoms, history and a repeat test. Labs differ, so check the result against the range on your client's report. Nothing you enter is stored or sent.
How do you arrange Fasting Glucose testing through Vively?
- Get verified. Practitioners with a recognised qualification or membership (ATMS, NHAA, ANTA, Dietitians Australia, NSA, CMA or Ahpra registration) can request free practitioner access.
- Choose a panel. Log in to the practitioner platform and pick a panel that includes Fasting Glucose, or build your own. It is included in the $99 Baseline Health Check.
- Client collects. Your client collects at a partner collection centre, with their request on their phone or printed.
- Review results. Results come back to you in the practitioner platform, beside your client's other markers, ready for the follow-up consult.
Which Vively panels include Fasting Glucose?
Log in to the practitioner platform to view a panel in full, or build and save your own from 100+ tests and panels.
- Baseline Health Check74 markers across 11 lab groups$99
One fasting blood draw.
Full Blood CountUrea, Electrolytes & CreatinineLiver Function TestsCalcium, Phosphate & MagnesiumLipid StudiesDiabetes & Glycaemic StudiesIron StudiesThyroid Function Tests+3 moreLog in to view this panel - Log in to view this panelMetabolic Panel3 markers · Heart & metabolicPrice on sign-up
- Log in to view this panelFull Body Health Check87 markers · Health checksPrice on sign-up
How do you read Fasting Glucose without an optimal range?
No separate optimal range: glucose is tightly defended and often stays within 3.4 to 5.4 mmol/L until insulin resistance is well established, so we read it with other markers.
Vively's clinical view is that insulin resistance typically appears 10 to 15 years before glucose becomes diagnosably impaired. We also read glucose against the client's own trend.
Above many lab ranges but below the Australian impaired fasting glucose cut-off of 6.1 mmol/L. RACGP guidance treats 5.5 to 6.9 mmol/L as a reason for further testing, usually HbA1c or an oral glucose tolerance test.
These are the Australian thresholds for impaired fasting glucose and the diabetes range. A doctor confirms the diagnosis.
What should Fasting Glucose be read with?
- ContextGlucose in range, fasting insulin above 10 mIU/L
Often seen with early insulin resistance that glucose alone misses.
- ContextGlucose 5.5 to 6.0 mmol/L, high triglycerides, low HDL
A common insulin resistance pattern and worth acting on with lifestyle work now.
- HighHigh fasting glucose, normal HbA1c
Often a one-off rise from poor sleep, stress, illness or the dawn phenomenon; repeat before drawing conclusions.
- ContextNormal fasting glucose, raised HbA1c
Possible glucose running high after meals, or to iron deficiency inflating HbA1c.
What can affect a Fasting Glucose result?
- An incomplete fast, or a late heavy meal.
- Delayed processing: cells in the tube keep using glucose, so a sample left too long can read falsely low.
- Hard training, acute illness or poor sleep in the previous 24 hours.
- Corticosteroids, thiazide diuretics and some antipsychotics, which raise glucose.
- Fasting well beyond 12 hours, or alcohol the night before, which can lower it.
When should you refer the client to their GP?
- Fasting glucose 7.0 mmol/L or above: GP review within days to confirm.
- 6.1 to 6.9 mmol/L: routine GP review to agree a plan and retest.
- High glucose with marked thirst, frequent urination, weight loss, vomiting or drowsiness: same-day care.
- Glucose below 3.5 mmol/L, or repeated shakiness, sweating or confusion.
- Pregnancy, so the GP can follow gestational diabetes screening.
How should a client prepare for a Fasting Glucose test?
Copy or print this to send to your client.
Preparing for your Fasting Glucose test
- Fast for 8 to 12 hours before a morning collection, water only.
- Skip exercise on the morning of your test, as it can shift your glucose.
- If you take diabetes medicines, check with your GP before you fast.
- Take your pathology request to any of 4,000+ collection centres. Bring it printed or on your phone.
- Keep taking prescribed medicines as usual unless your doctor tells you otherwise.
- Results usually take 3 to 5 business days and come to your practitioner. Book your results appointment for after that.
How do practitioners use Fasting Glucose with clients?
Fasting glucose responds to adequate protein, healthy fats and fibre from low GI carbohydrates such as legumes and wholegrains, with better sleep and stress control. Repeat a single borderline result before drawing conclusions.
Fasting Glucose FAQs
Can a dietitian, nutritionist or naturopath order fasting glucose through Vively?
Yes. Add it to a client panel on the Vively practitioner platform. It is part of Diabetes & Glycaemic Studies in the $99 Baseline Health Check, and is also in Full Body Health Check and Metabolic Panel. No account yet? Request free access.
Is a fasting glucose of 5.6 mmol/L prediabetes?
Not by Australian criteria. Diabetes Australia and the RACGP define impaired fasting glucose as 6.1 to 6.9 mmol/L, while the American Diabetes Association starts at 5.6 mmol/L. In Australia, 5.5 to 6.9 mmol/L is a reason for further testing, usually HbA1c or an oral glucose tolerance test, and a result like this is worth acting on with lifestyle work.
Should I repeat a high fasting glucose before referring?
Refer at 7.0 mmol/L or above without waiting. Below that, a repeat after a confirmed 8 to 12 hour fast, a normal night's sleep and no hard training the day before is reasonable. A diagnosis of diabetes needs a doctor and usually a second abnormal result or an HbA1c of 48 mmol/mol or above.
What does a normal fasting glucose not tell me?
It does not rule out insulin resistance. The body defends fasting glucose tightly, so it often stays within 3.4 to 5.4 mmol/L until insulin resistance is well established. Read it alongside fasting insulin, HOMA-IR, HbA1c and the client's own trend before concluding that their glucose handling is fine.
What can make a fasting glucose read falsely low or high?
Delayed processing lowers it, because cells in the tube keep using glucose. An incomplete fast or late heavy meal raises it, as do hard training, acute illness, poor sleep, corticosteroids and thiazide diuretics. Fasting well beyond 12 hours or alcohol the night before can lower it. Confirm collection conditions before acting on an odd result.
References
- Royal Australian College of General Practitioners. Management of type 2 diabetes: a handbook for general practice. 2020.
- Royal College of Pathologists of Australasia. RCPA Manual: Glucose.
- Pathology Tests Explained. Glucose.
- Dunstan DW, Zimmet PZ, Welborn TA, et al. The rising prevalence of diabetes and impaired glucose tolerance: the Australian Diabetes, Obesity and Lifestyle Study. Diabetes Care. 2002. Source
- American Diabetes Association. Standards of Care in Diabetes. Source