The short answer
Detects insulin resistance early — often years before blood sugar becomes abnormal, measured from a standard blood draw. At TestWell it costs $22.99 plus a $6 lab processing fee, requires an 8–12 hour fast, and results post in 2–4 business days. Physician-authorized with no doctor's visit or insurance needed; draw at Quest or Labcorp.
Hospital Lab
$130
cash pay
Other Labs
$45
+ lab fees
TestWell
$22.99
+ $6 lab processing fee
Fasting insulin measures how much insulin your pancreas is producing to keep blood sugar in range. Elevated fasting insulin is one of the earliest signs of insulin resistance, often appearing years before glucose or A1c levels become abnormal. This makes it a valuable early-detection tool for Type 2 diabetes risk and metabolic syndrome.
Fasting insulin — the earliest marker of insulin resistance, often elevated 5-10 years before A1c rises. Paired with glucose to calculate HOMA-IR.
Anyone with central obesity, PCOS, family history of type 2 diabetes, fatty liver, or doing a metabolic optimization workup. The most sensitive single marker of pre-diabetes physiology.
Sample Type
Blood draw
Fasting
Required
Results In
2–4 business days
Performed At
Quest or Labcorp
Your Insulin, Fasting results will include values for each of the 1 biomarker tested, along with reference ranges. Results are reviewed by a licensed physician before being released to your secure portal.
If any values fall outside the normal range, your report will include guidance on what that may mean and recommended next steps. You'll receive an email notification when your results are ready, typically within 2–4 business days.
Typical reference range layout
Lab reports show where your value sits relative to established reference intervals—your physician interprets this in context for you. Already have results? Analyze them with your AI assistant against our physician-reviewed ranges.
Fasting for 8–12 hours is required. Water is okay.
What can throw off this result
Physician-reviewed “Before your test” pages — what each factor does, for how long, and what to do about it.
The short answer
Worth it if you want an early read on insulin resistance. Fasting insulin often rises years before glucose or A1c budge, so it can flag metabolic trouble early - but it is best interpreted alongside a fasting glucose, not on its own.
We would rather you order the right test than the most expensive one.
Fasting insulin is a venous draw at Quest or Labcorp, or an at-home mobile draw where available, after 8-12 hours without food (water and medications are fine). Pair it with a fasting glucose from the same draw to calculate insulin resistance (HOMA-IR).
The markers that matter most and what an out-of-range value can mean. Reference ranges vary by lab, age and sex.
| Marker | Typical range | What it means |
|---|---|---|
| Fasting insulin | ~2-19 uIU/mL (lab range) | Many clinicians view single digits as more favorable; higher fasting insulin with normal glucose is an early sign of insulin resistance. Ranges vary widely by lab and assay. |
| Paired with fasting glucose | Glucose 70-99 mg/dL | Insulin and glucose together (HOMA-IR) describe insulin resistance better than either number alone. |
This section medically reviewed by Youmna DiStefano, MD — updated June 2026. General health information, not medical advice; interpret results with a qualified clinician.
A Fasting Insulin test costs $22.99 at TestWell — $28.99 all-in when ordered alone, because the $6 lab processing fee is charged once per order, with no draw fee or physician fee added. Hospital outpatient labs typically bill around $130.00 self-pay for the same test, and often more. With insurance, what you pay depends on your deductible and your plan's negotiated rate; TestWell's price is fixed before the draw and is HSA/FSA-eligible.
| Where you order | Price | One test, all-in | Notes |
|---|---|---|---|
| TestWell (drawn at Quest) | $22.99 | $28.99 | Includes the one $6 lab processing fee, charged once per order |
| TestWell (drawn at Labcorp) | $23.99 | $29.99 | Labcorp's own cost for this test is higher; same order, same portal, same physician review |
| TestWell (drawn at BioReference — New York & New Jersey) | $23.99 | $29.99 | New York and New Jersey orders route to BioReference; Quest Health and Labcorp OnDemand don't take self-ordered draws in those states |
| Hospital outpatient lab, self-pay (typical) | $130.00 | $130.00 | Reference figure; hospital charges vary widely by facility and are often higher |
Lab test codes: Quest test code 561 · Labcorp test no. 004333 · BioReference code 1648-5. Competitor prices are read from the linked public pages and re-checked regularly; the labs' sites may add taxes or change prices without notice.
Compare more: Quest Diagnostics price list · Labcorp price list · Quest vs Labcorp · Lab test price checker
A1c only rises after years of glucose regulation failure. Fasting insulin rises first — the pancreas pumps out more insulin to keep glucose normal. By the time A1c is elevated, insulin resistance has been brewing for 5-10 years. Catch it early with fasting insulin.
Yes — strict 9-12 hours of fasting (water only). Insulin spikes within minutes of food intake; non-fasting results are uninterpretable.
Conventional reference: 2-25 uIU/mL (huge range). Functional optimal: <8 uIU/mL. 8-15: early insulin resistance. >15: significant insulin resistance regardless of normal glucose.
HOMA-IR = (Fasting Insulin × Fasting Glucose) / 405. <1.5 is optimal, 1.5-2.5 is borderline, >2.5 indicates insulin resistance. Order Glucose alongside and we'll show the calculation on your results page.
They answer different questions. A1c tells you your average blood sugar over 2-3 months and is the diabetes screening standard. Fasting insulin can reveal insulin resistance earlier, while A1c and glucose still look normal. For an early metabolic read, many people run both plus a fasting glucose.
Fast 8-12 hours (overnight is easiest); water and most medications are fine. Because insulin spikes after eating, a non-fasting result is difficult to interpret, so fasting matters more here than for many other tests.
HOMA-IR is a simple calculation from your fasting insulin and fasting glucose that estimates insulin resistance. Order both from the same draw and the numbers let you (or your provider) compute it - a more informative metabolic read than glucose alone.
Eating before the draw, sleep deprivation, keto and high-protein diets and peptides and GLP-1s can change a Fasting Insulin test result without anything being wrong. Eating before the draw can raise Insulin — fast 8–12 hours; water only. Sleep deprivation can raise Insulin — avoid glucose and insulin testing after an all-nighter. Keto and high-protein diets can lower Insulin — none needed — expected improvement. Peptides and GLP-1s can raise Insulin — growth hormone opposes insulin; check glucose or A1c alongside IGF-1. Each factor is covered on our physician-reviewed "Before your test" pages; when one applies, the fix is usually to remove it and retest.
Order the Fasting Insulin test online from TestWell for $22.99 (plus a $6 per-order lab processing fee) — no doctor's visit, referral or insurance needed. A licensed physician authorizes the order, then you walk into any Quest or Labcorp patient service center near you for the draw (the lab locator on our site lists the closest ones by ZIP code), and results arrive in 2–4 business days.
The CPT code for a Fasting Insulin test is 83525. You can order it from TestWell for $22.99 — no doctor's visit or insurance required, with results in 2–4 business days.
The Fasting Insulin test is Quest Diagnostics test code 561, Labcorp test number 004333, BioReference code 1648-5 (CPT 83525). TestWell orders it under those codes for $22.99 at Quest, Labcorp or BioReference — no doctor's visit or insurance required, results in 2–4 business days. Codes verified against the labs' catalogs in 2026.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
Related guide
Metabolic Lab Testing: Which Panel Do You Actually Need?
Related guide
A1c Levels Explained: Normal Ranges, Prediabetes Cutoffs, and What Can Skew Your Number
TestWell Price
$22.99
+ $6 lab processing fee at checkout
No insurance needed · HIPAA compliant
Better value: the Diabetes Screening Panel
Save $9.98This test is part of the Diabetes Screening Panel — 3 tests · 3 biomarkers for $59.99, $9.98 less than à la carte.
$59.99$69.97
3 tests · 3 biomarkers
Frequently ordered together
Customers who ordered Insulin, Fasting also added these for a more complete health picture.
Not sure where to start?
Insulin, Fasting
$22.99