Glucose

What is Glucose?

Fasting glucose is your blood sugar after a night without food. It shows how well your body keeps your sugar level at rest. A stable fasting value points to a smoothly running metabolism.

Clinical frame

Fasting glucose reflects glucose regulation after at least 8 hours without calorie intake and is an important parameter for detecting prediabetes and diabetes ^[2].

In the context of insulin resistance, however, fasting glucose is above all a later marker of metabolic dysregulation. Insulin resistance and compensatory hyperinsulinaemia can be present for years while fasting glucose remains normal ^[1]. A normal value therefore does not rule out insulin resistance.

When fasting glucose starts to rise, this mainly points to hepatic insulin resistance and increasing beta-cell dysfunction. Insulin then no longer manages to suppress glucose production by the liver sufficiently, so glucose remains elevated even in the fasting state ^[3].

For the early detection of insulin resistance, HOMA-IR, the TyG index and triglycerides/HDL are more sensitive than fasting glucose alone ^[1]. The value therefore gains its meaning mainly in combination with other metabolic markers and the broader risk profile.

What moves this value?

Too little or too much sleep, stress and little exercise can temporarily raise your morning value. A high calorie intake, fast carbohydrates, sugary drinks and heavily processed food also play a part.

Healthy weight loss often has the greatest impact. Regular exercise, walking after meals, fibre-rich food and a regular sleep pattern help improve your value further.

What this connects

• HbA1c
• HOMA-IR
• Triglycerides

References

1. Roden, M. & Shulman, G. I. The integrative biology of type 2 diabetes. Nature 576, 51–60 (2019). doi.org/10.1038/s41586-019-1797-8
2. Unnikrishnan, R. et al. Prediabetes. Nat Rev Dis Primers 11, 49 (2025). doi.org/10.1038/s41572-025-00635-0
3. Bock, G. et al. Contribution of hepatic and extrahepatic insulin resistance to the pathogenesis of impaired fasting glucose: role of increased rates of gluconeogenesis. Diabetes 56, 1703–1711 (2007). doi.org/10.2337/db06-1776