Fasting Blood Glucose
Fasting blood glucose is the snapshot of your blood sugar after 8+ hours without food — the most basic screening test for diabetes.
What it measures
Fasting glucose is measured after at least 8 hours without caloric intake (water is allowed). At that point insulin and counter-regulatory hormones are at baseline, so the reading reflects how well your body handles glucose at rest. It is one of the three accepted ways to diagnose diabetes (the others being HbA1c and the 2-hour value during an oral glucose tolerance test). Single-day readings can vary; clinicians repeat the test before acting.
What a high value can mean
- 100–125 mg/dL — impaired fasting glucose / prediabetes. Reversible in most patients with lifestyle change.
- ≥126 mg/dL on two occasions — meets diabetes diagnostic threshold.
- >250 mg/dL with symptoms — call your doctor today; risk of dehydration and acidosis.
- Stress, infection, steroid medication — transient elevation without true diabetes.
What a low value can mean
- Hypoglycaemia — symptomatic below 70 mg/dL: shakiness, sweating, confusion.
- Insulin overdose / sulfonylurea — common in treated diabetes.
- Prolonged fasting, alcohol on empty stomach, heavy exercise.
- Rare conditions — insulinoma, adrenal insufficiency.
When to discuss with a doctor
Fasting glucose 100–125 mg/dL once is worth repeating; persistent values in this range need a primary-care visit to discuss lifestyle and possibly an HbA1c. A reading ≥126 mg/dL with symptoms (excessive thirst, frequent urination, weight loss) warrants prompt evaluation. Mediora.AI plots your fasting trajectory alongside HbA1c so the pattern is obvious.