The fasting glucose test measures your blood sugar level after not eating for at least 8 hours. It's the standard screening test for diabetes and prediabetes.
Fasting glucose is one of the most commonly ordered blood tests and a cornerstone of diabetes screening. By measuring blood sugar after an overnight fast, this test reveals how well your body regulates glucose when no food is present.
When you fast, your liver releases stored glucose to maintain normal blood sugar levels. In healthy individuals, insulin keeps this process in check, maintaining fasting glucose typically between 70-99 mg/dL. When insulin resistance develops or the pancreas can't produce enough insulin, fasting glucose rises.
This simple, inexpensive test can detect diabetes, identify prediabetes (when intervention is most effective), and help monitor glucose control in people with diabetes. It's often part of routine annual bloodwork.
Price
$6
Results
1 days
Lab Network
Quest
Fasting
8+ hrs
What's Measured
What This Test Measures
This test measures the concentration of glucose (sugar) in your blood after fasting, reported in mg/dL. Normal fasting glucose is 70-99 mg/dL. Prediabetes is 100-125 mg/dL. Diabetes is diagnosed at 126 mg/dL or higher (when confirmed on repeat testing).
Who Should Consider This Test
Anyone over age 35 for routine diabetes screening, people with diabetes risk factors (overweight, family history, sedentary lifestyle), those with symptoms of high blood sugar, and anyone wanting to understand their metabolic health.
Health Insights
Conditions Screened
Related Symptoms
When to Get Tested
Fasting for 8-12 hours is required. Water is allowed and encouraged. Best done first thing in the morning after an overnight fast. Avoid alcohol the night before.
Fasting Required
This test requires fasting for accurate results. Please follow these instructions:
- Do not eat or drink anything except water for 8-12 hours before your blood draw.
- Water is allowed and encouraged - stay hydrated!
- Schedule your lab visit in the morning for convenience.
- Continue taking any prescribed medications unless advised otherwise by your doctor.
Understanding Your Results
Normal: 70-99 mg/dL. Prediabetes (impaired fasting glucose): 100-125 mg/dL. Diabetes: 126 mg/dL or higher (requires confirmation on a second test). Values below 70 may indicate hypoglycemia and should be discussed with your healthcare provider.
Dig deeper into this test with this recommended article:
What to Expect
After placing your order, you'll receive an email from Rupa Health (our lab order partner) within 24 business hours to sign a consent form and schedule your blood draw at a Quest Diagnostics location.
The blood draw typically takes just a few minutes. Results are usually available within 1 business days and will appear in your secure Justlabs dashboard.
Our results include reference ranges and easy-to-understand indicators showing whether your values are within normal limits.
Frequently Asked Questions
$6
Typical hospital cash price: $150–$250
+ $28 in standard lab & physician fees at checkout (no additional bills later)
$18 lab collection + $10 physician order
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