What the value means
Fasting glucose shows how well your body holds blood sugar after a night without food. Laboratories use different reference ranges – often up to 5.6 or up to 6.0 mmol/L. The American Diabetes Association defines 5.6–6.9 mmol/L as impaired fasting glucose, the WHO uses 6.1–6.9 mmol/L. So a value “within range” is not necessarily optimal: in large population studies, levels above about 5.5 mmol/L are linked with a higher risk of later diabetes. Still, a single measurement is not a diagnosis.
Possible causes
- Insulin resistance – cells respond less to insulin, typically with abdominal fat and little exercise.
- Poor sleep and stress – cortisol and adrenaline raise morning sugar (the so-called dawn phenomenon).
- Late dinner or an incomplete fast – fewer than 8–10 hours without food distorts the result.
- Acute illness – an infection or fever raises glucose temporarily.
- Some medicines – for example corticosteroids; whether you need them is your doctor’s call.
- Genetics and age – a family history of diabetes increases the likelihood.
What you can do
- Repeat the test – rested, after an 8–12 hour fast and a good night’s sleep; ask for HbA1c too.
- Move after meals – a 10–15 minute walk after your main meal blunts glucose spikes.
- Strength training – muscle is the largest consumer of glucose; aim for 2–3 sessions a week.
- Diet – more fibre, protein and vegetables, fewer sugary drinks and refined flour products.
- Weight and sleep – losing 5–7 % of body weight and sleeping 7–9 hours are among the strongest prevention tools.
When to see a doctor
Discuss the result with your doctor, especially if the raised value repeats, your HbA1c is elevated, diabetes runs in your family or you have high blood pressure. Seek care promptly if fasting glucose is 7.0 mmol/L or higher, or if you have marked thirst, frequent urination, unexplained weight loss or blurred vision. Your doctor may also suggest an oral glucose tolerance test.