BiomarkersFasting glucose

Blood sugar

Fasting glucose

Your blood sugar after an overnight fast

On your report it may say: Fasting blood sugar, FBS, Fasting plasma glucose

Fasting glucose shows how well your body keeps blood sugar in check without food. Diabetes and prediabetes are very common in India, often without symptoms, so regular checks matter.

Updated 2026-10-26

Typical ranges · mg/dL

Low below 70
In range 70–100
Prediabetes 100–126
Diabetes range 126+

mmol/L = mg/dL ÷ 18

A diabetes diagnosis needs a repeat test or a second test such as HbA1c.

Ranges vary by lab, age and sex. The range printed on your report applies.

If it's low

Blood sugar is low; this is uncommon without diabetes medicines.

Common causes

  • Diabetes medicines or insulin
  • Long fasting or heavy exercise
  • Alcohol
  • Rare hormone conditions

What you might notice

  • Shakiness
  • Sweating
  • Hunger
  • Confusion

If it's high

Your body isn't clearing sugar well, which raises the risk of diabetes and heart disease.

Common causes

  • Insulin resistance
  • Excess weight, especially around the waist
  • Low activity
  • Family history
  • Steroids and some medicines

What you might notice

  • Often none
  • Thirst and passing more urine
  • Tiredness
  • Slow-healing cuts

Testing

Who should test
All adults over 30 in India, and earlier with excess weight, family history or PCOS.
How to prepare
Fast 8–12 hours (water is fine).
When to retest
Every year if normal; every 3–6 months if in the prediabetes range.

What can help

SYNC doesn't change your plan from this result alone. Use these only alongside your doctor's advice.

Food sources

High-fibre whole grains (bajra, jowar, oats)Dal and pulsesVegetablesNutsFewer sugary drinks and refined carbs

See a doctor if fasting glucose is 100 or above, or below 70.

Common questions

Is one high result diabetes?

Not on its own; doctors confirm with a repeat or HbA1c.

Can prediabetes go back to normal?

Often yes, with weight loss, activity and diet changes.

Explore further

Sources

  1. MedlinePlus (US National Library of Medicine): Blood glucose test

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For general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.