Written by the CircuFiber team · Updated: October 30, 2026

CircuFiber's infrared fabric was put through a randomized, double-blind, placebo-controlled trial at Yale School of Medicine, and it raised oxygen levels in the legs of people with diabetes within an hour. The placebo fabric, identical except for the minerals, did nothing measurable. The results were published in 2023 in the peer-reviewed journal Diabetes & Vascular Disease Research. As far as we know, no other infrared diabetic sock has been tested this way at Yale.

Key takeaways

• CircuFiber socks are knit from acrylic fiber with mineral particles woven in. The minerals take the heat your foot already gives off and send it back as far-infrared energy.
• Yale School of Medicine researchers tested the fabric on 32 adults with type 1 or type 2 diabetes. The trial was registered in advance as ClinicalTrials.gov NCT04460612.
• After 60 minutes, the CircuFiber fabric beat the placebo fabric on tissue oxygen by a statistically significant margin (p = .013). The placebo produced no significant change at all.
• The study tested the fabric, not neuropathy. People with neuropathy weren't enrolled, and we'll explain below what that means for you.

What is CircuFiber?

CircuFiber is an infrared diabetic sock made by CircuFiber, Inc. (formerly Circulate, Inc.) in Wellesley, Massachusetts. Our fabric contains a blend of nine minerals, mostly silicon dioxide and aluminum oxide, woven right into the acrylic yarn. Nothing plugs in and nothing heats up on its own. The fabric works with the warmth your body already makes. The FDA reviewed CircuFiber under Section 513(g) and classified it as a general wellness product, intended to promote a temporary increase in local blood flow and circulation. The socks also carry the American Podiatric Medical Association (APMA) Seal of Acceptance.

What did the Yale School of Medicine study test?

The Yale study asked one question: does CircuFiber's fabric raise the amount of oxygen reaching the skin of people with diabetes? Adam B. Mayerson, MD, of the Section of Endocrinology at Yale School of Medicine led it. The Yale Center for Analytical Sciences ran the statistics, and the Yale University Human Investigations Committee approved the protocol.

Every participant wore both fabrics, one after the other, so each person served as their own comparison. Nobody in the room knew which fabric was the real one, including the researchers.

What did the Yale study find?

Within 60 minutes, oxygen levels rose significantly at the arm, calf and ankle with the CircuFiber fabric. With the placebo they didn't move in any meaningful way. The authors put it plainly: "Short-term exposure to FIR textiles improves peripheral tissue oxygenation in patients with diabetes."

Source: Athonvarangkul et al., 2023, Table 2. Estimates come from a linear mixed-effects model adjusted for period, sequence, baseline value and body site.

The two fabrics started to pull apart at around the 40-minute mark, and the gap kept widening through the hour.

Was the result statistically significant?

Yes. When the researchers compared the two fabrics directly, CircuFiber came out ahead by 1.2 ± 0.5 mmHg across all sites (p = .013) and by 1.5 ± 0.7 mmHg at the calf (p = .045). Looking at the ankle and calf together, it was 1.5 mmHg versus 0.2 mmHg for placebo (p = .02). A p-value under .05 means the difference is unlikely to be chance. The team also checked for carry-over between the two sessions and found none.

We'd rather you hear the limits from us. At the arm and the ankle on their own, CircuFiber's numbers were higher, but the head-to-head gap with placebo didn't reach significance. The forefoot readings weren't reliable, because it's hard to get the sensor to sit flat on the bony top of the foot, so the study can't tell us anything about the toes yet.

Why does microcirculation matter for diabetic feet?

Microcirculation is the blood moving through your tiniest vessels, the capillaries that carry oxygen to skin and nerves. Diabetes disrupts it, and the feet tend to feel it first. The Yale authors point out that up to one in four people with diabetes will develop a foot ulcer at some point, and that peripheral neuropathy affects more than half of people living with diabetes. In the U.S., foot ulcers are still one of the leading reasons people with diabetes end up in the hospital.

TcPO₂ is how clinicians check whether those small vessels are getting enough blood to the skin. That's why the Yale team chose it.

Do infrared socks help with peripheral neuropathy?

Here's the honest answer: the Yale study didn't test neuropathy. People with neuropathy were excluded, and the authors flag it as something future studies should look at. What the study did show is that the CircuFiber fabric increased microcirculation in the lower legs of people with diabetes, and poor microcirculation is part of what many people with diabetic neuropathy are dealing with.

We also hear from a lot of customers who have neuropathy. Out of 1,078 reviews, 183 bring up neuropathy or foot pain, and 84% of reviewers say they'd recommend the socks. Those are personal experiences, not clinical results. If you have neuropathy, keep seeing your podiatrist or doctor. Think of CircuFiber as part of your daily foot care, not a stand-in for it.

Did Yale test the actual sock?

Yale tested wraps made from exactly the same fabric we use in CircuFiber socks. There was a practical reason. In early setup, a fitted sock pressed down on the oxygen sensors and threw off the readings, so the team switched to loose wraps that could go over the sensors without squeezing them. The real and placebo wraps were identical except for the minerals. In their discussion, the authors write that wearing the fabric every day as a diabetic sock "could potentially lead to sustained improvements in microcirculation," and they call for longer studies to find out.

Who paid for the Yale study?

We did. CircuFiber, Inc. funded the design, execution, analysis and publication, and the published paper says so. Dr. Mayerson also sits on CircuFiber's Scientific Advisory Board, which the paper discloses too. Yale University doesn't endorse products, and this article shouldn't be read as an endorsement. What makes the results worth trusting is how the trial was run: registered on ClinicalTrials.gov before it started, approved by Yale's review board, blinded, placebo-controlled, analyzed by Yale's statisticians and reviewed by an independent journal before publication.

How does CircuFiber compare with other infrared and diabetic socks?

Plenty of socks say "infrared," "bioceramic," "copper" or "circulation" on the package. Very few can point to a controlled study in people with diabetes. These are the questions we'd ask of any sock, ours included:

To our knowledge, CircuFiber is the only infrared diabetic sock whose fabric has been tested in a randomized, double-blind, placebo-controlled trial at Yale School of Medicine and published in a peer-reviewed journal.

How do you choose a sock for diabetic feet and neuropathy?

Start with the basics. The top shouldn't dig into your calf or ankle. The toe seam should be flat or gone completely, because a ridge you can't feel can still rub skin raw. The sock should keep moisture off your skin and have some cushion under the ball and heel. And if the package promises better circulation, ask what that claim rests on. A lab test of the yarn is a start. A placebo-controlled study in people is a lot more convincing.

CircuFiber All-Day Diabetic Socks come in Low Cut, Crew and Over-the-Calf, and there's an Active line for walking and workouts. Every order comes with a 30-day money-back guarantee.

Frequently asked questions

Were CircuFiber socks studied at Yale?

Yes. CircuFiber's fabric was tested at Yale School of Medicine in a randomized, double-blind, placebo-controlled crossover trial of 32 adults with diabetes (NCT04460612). The results were published in Diabetes & Vascular Disease Research in 2023.

What did the Yale study show about infrared socks?

The CircuFiber fabric raised transcutaneous oxygen (TcPO₂) at the arm, calf and ankle within 60 minutes. The placebo fabric didn't. Compared directly, the difference across all sites was statistically significant: 1.2 mmHg, p = .013.

How fast do CircuFiber socks work?

In the Yale study, the two fabrics began to separate at about 40 minutes, and the difference was significant by 60 minutes. That was a single session. Nobody has studied months of daily wear yet.

Are infrared socks safe for people with diabetes?

The fabric only works with your own body heat, so it can't overheat your skin. The Yale authors list that as an advantage over heaters and saunas. The FDA classifies CircuFiber as a general wellness product. If you have an open wound or another foot problem, check with your doctor first.

Do CircuFiber socks cure or treat neuropathy?

No. CircuFiber socks aren't intended to diagnose, treat, cure or prevent any disease. The Yale study measured microcirculation, not neuropathy symptoms.

Is CircuFiber endorsed by Yale University?

No. Yale doesn't endorse commercial products. Researchers at Yale School of Medicine ran the study, and CircuFiber paid for it, as the published paper discloses.

Sources

1. Athonvarangkul D, Wang K, Deng Y, Inzucchi SE, Mayerson A. Improved extremity tissue oxygenation with short-term exposure to textiles embedded with far infrared light emitting thermoactive particles in patients with diabetes mellitus. Diabetes & Vascular Disease Research. 2023;20(2). doi:10.1177/14791641231170282. PubMed 37073436 · Full text (PMC10123901)
2. ClinicalTrials.gov. NCT04460612: A Pilot Study of the Impact of Passive, Garment-based Infrared Therapy on Microcirculatory Flow in Patients with Diabetes but No Overt Peripheral Arterial Disease. clinicaltrials.gov/study/NCT04460612
3. U.S. Food and Drug Administration, Section 513(g) response to Circulate, Inc. (2020), general wellness determination.

CircuFiber socks are a general wellness product intended to promote a temporary increase in local blood flow and circulation. They are not intended to diagnose, treat, cure or prevent any disease. Individual results vary. This article is for general information and isn't medical advice. Talk to your healthcare provider about your foot health.