Fasting glucose

What it means

The test is usually done first thing in the morning, before breakfast, with water allowed. It can be part of a routine blood panel or a quick finger-stick check.

CDC cutoffs for fasting blood sugar:

• 99 mg/dL or below: normal
• 100 to 125 mg/dL: prediabetes
• 126 mg/dL or higher: diabetes

A diabetes diagnosis generally needs two abnormal results, either the same test repeated or two different tests such as fasting glucose and A1C. Illness, stress, some medicines and poor sleep can raise a single reading.

Fasting glucose shows one moment, while A1C reflects about 3 months. Many clinicians look at both. If you have diabetes and check at home, your care team will set personal targets, which may differ from the screening ranges above.

Why it matters

Fasting glucose often improves early in GLP-1 treatment, giving a measurable sign of metabolic change beyond weight.