InsideTracker vs Function Health: which blood testing service is better?

InsideTracker vs Function Health: quick answer

On price and breadth, Function Health wins clearly: $365 a year for 160+ tests across two Quest draws (about $2.28 per result), with clinician notes. InsideTracker costs $489 for a year of membership and one Ultimate test of up to 54 biomarkers (about $9.06 per marker). Our scores reflect that: Function 8.3, InsideTracker 6.2.

InsideTracker earns its place with athletes and people who want highly specific food, training and sleep advice, DNA analysis and wearable data in one app. Both require a venous blood draw; if that is the problem, jump to the at-home alternative. Prices were checked on both companies' sites on September 29, 2026.

No needle, no lab visitSiPhox Health: 31 biomarkers from an upper-arm draw at home. $124 plus $25 shipping per test.

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Side by side

Price and cost per biomarker

For one year of testing:

• Twice a year: Function $365. InsideTracker $761 (membership plus two tests).
• Four times a year: Function cannot do this inside the membership. InsideTracker $1,305 for new customers, $1,088 plus the $149 membership renewal for existing members.
• New York or New Jersey: Function is higher (one review reports $600+). InsideTracker requires the $119 mobile draw, so $608 for one test.

Both are HSA and FSA eligible and neither takes insurance. See the full Function Health cost breakdown and our InsideTracker review for plan details.

InsideTracker's value case rests on what it does with the numbers, not on the numbers per dollar. If you would use the membership mainly to see your labs, Function gives more for less.

Company background

InsideTracker was founded in 2009 by scientists from MIT and Tufts and is one of the longest-running consumer blood analysis platforms. Function Health was founded in 2021, is based in Austin, raised a $298 million Series B at a $2.5 billion valuation in November 2025, and has since bought Ezra (MRI scans), Getlabs (home draws) and SuppCo (supplement ratings). Function is growing fast and adding services; InsideTracker is the smaller, more specialized product. Neither is a medical practice you can rely on for ongoing care.

Both keep your data in their own apps. If you might switch later, save copies of every report as you go, so you can upload them to the next service or share them with your doctor; one recent Function one-star review complained about limited export options.

Biomarkers

Both cover the modern heart and metabolic markers: ApoB, HbA1c, fasting insulin, hs-CRP, testosterone, TSH, vitamin D and ferritin. Function goes much further: Lp(a), LDL particle size, thyroid antibodies, homocysteine, omega-3 and omega-6, lead and mercury, autoimmunity markers, kidney and liver panels and a urinalysis. InsideTracker's list adds performance markers such as creatine kinase, and it does not publish a full current list on its store.

Draw, results and follow-up

Both send you to Quest for a venous draw, and both offer a home phlebotomist for a fee. Function asks for an 8-hour fast and takes about 35 to 85 mL of blood across its panels. Function's first results arrive in about 48 hours, with clinician notes to follow; InsideTracker quotes up to 7 business days.

The follow-up philosophies differ. Function gives clinician commentary and a protocol. InsideTracker gives more granular, data-driven targets tied to your training, sleep and DNA. Recent complaints differ too: Function's one-star reviews focus on slow, AI-heavy support; InsideTracker's on app usability, expiring prepaid tests and a shift to subscriptions.

Reviews compared

On September 29, 2026 Function had 4.5 out of 5 from about 2,990 Trustpilot reviews (6% one-star), and InsideTracker 4.0 from 617 (13% one-star). InsideTracker received only 17 reviews in the previous 12 months, against a steady flow for Function, which says something about where new customers are going. In the 20 most recent Function one-star reviews we read, support (8 mentions) and late or incomplete results (4) led the list.

Availability by state

Recommendations compared

Function's reports lean clinical: a clinician flags results that need attention and a protocol suggests food, supplement and lifestyle changes. InsideTracker's lean performance: each marker gets an "optimal zone" for your age, sex and activity, and the plan ties food and training changes to specific markers, optionally informed by DNA. Neither replaces your doctor, and neither will prescribe for most findings. If a result is well outside the lab's reference range, get it confirmed with a venous test ordered by your doctor.

Which is better for heart health?

Function. It includes ApoB, Lp(a), LDL particle number and size, hs-CRP and homocysteine in the base price. Lp(a) is largely inherited, and the National Lipid Association's 2024 update recommends measuring it at least once in every adult; we did not find it on InsideTracker's list.

Which is better for athletes?

InsideTracker. It was built around performance, reads markers such as creatine kinase, iron status and cortisol against training load, and connects to Garmin, Whoop, Oura and Strava. Function covers many of the same markers but frames them for general health.

Can you use both?

Possibly. InsideTracker's membership accepts uploaded lab results, and its store sells the $149 membership on its own (listed for international customers; ask whether US customers can buy it without a test). If so, you could run Function's draws and upload them to InsideTracker for its recommendations, for about $514 a year and still two venous draws.

Who should pick which

• Pick Function Health if you want the biggest baseline for the money, clinician notes, and are fine with two draws a year. Most readers belong here.
• Pick InsideTracker if you are an endurance athlete or lifter who wants training-specific targets, DNA and wearable data, and will pay for it.
• Pick neither if you dislike needles, live far from Quest, or want to track a few markers every month or quarter. Compare Function's closest rival in Function Health vs Superpower, or see all the Function Health alternatives.

If you are torn, start from the markers. Heart prevention points to Function; training performance points to InsideTracker; frequent tracking of a short list points to an at-home kit. HbA1c is a good test case: it reflects roughly three months of blood sugar, so retesting every three months is the natural rhythm when you are trying to lower it, and both lab-draw services make that cadence expensive or impossible.

The at-home alternative: SiPhox Health

SiPhox Health is the option for people who want neither a lab visit nor a phlebotomist. You collect blood yourself with a needle-free device on your upper arm, ship it back cold overnight, and get results in 7 to 10 days. The default panel covers 31 biomarkers, including ApoB, Lp(a), HbA1c, hs-CRP and sex hormones, and you can test monthly, quarterly or twice a year, switching panels as you go.

It tests fewer markers per year than Function and does not include clinician notes. It is much cheaper per retest than InsideTracker ($149 vs $340). Read the head-to-heads: SiPhox vs Function Health and SiPhox vs InsideTracker.

Track your numbers at home$124 plus $25 shipping per test, first test advertised at $99. Switch panels each time. HSA and FSA accepted.

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