Glucose levels: what's normal, high and low
Your blood sugar level. Fasting glucose is one of the primary screens for diabetes.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
Glucose is measured with a standard blood draw after an 8–12 hour fast. A typical reference range is 70.0 – 99.0 mg/dL. At TestWell it's $20.99 all-in as Basic Metabolic Panel, results in 1–3 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- mg/dL
- Sample
- Blood draw
- Fasting
- 8–12 hours
- Results
- 1–3 business days
- Price
- $20.99
- Labs
- Quest or Labcorp · BioReference in NY/NJ
Glucose Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+, fasting | 70.0 – 99.0 mg/dL |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
What your Glucose result may mean
Fasting values above 100 mg/dL can indicate prediabetes; above 125 mg/dL on two separate tests suggests diabetes.
What a high Glucose means: causes, symptoms, next steps →Can reflect prolonged fasting, certain medications (especially diabetes drugs), or hormonal conditions.
What a low Glucose means: causes, symptoms, next steps →Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
How do you get a Glucose test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. Glucose is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| Basic Metabolic Panel | This marker only | $20.99 |
Quest vs. Labcorp for Glucose: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | Yes | $20.99 |
| Labcorp | Yes | $21.99 |
| BioReference (NY & NJ) | Yes | $22.99 |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
How often should you retest Glucose?
The ADA suggests re-screening at least every 3 years when fasting glucose is normal, and at least once a year with prediabetes (100–125 mg/dL). A single fasting result at or above 126 mg/dL is confirmed with a repeat test — or an A1c — before it counts as diabetes.
General guidance from the sources listed below — your clinician may set a different schedule based on your history and results.
Related Metabolic Health biomarkers
Markers commonly tested alongside Glucose.
Frequently asked
Fasting values above 100 mg/dL can indicate prediabetes; above 125 mg/dL on two separate tests suggests diabetes. A single result above the reference range is a prompt to look closer with a clinician — often a repeat test and related markers — not a diagnosis on its own.
Ready to test your glucose?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $20.99.