Monofilament test · numb feet

Monofilament Test: What It Means When You Can’t Feel Your Feet

Failing a monofilament test means the nerves that carry touch and pressure in your foot have lost ground. In a ten-year Scottish study of people with diabetes, it carried 2.7 times the risk of a first foot ulcer, and 54.9 percent of those who failed it died within the decade, against 37.2 percent of those who passed.

The thin filament pressed against your foot at a diabetes visit asks a simple question. Whether you can feel it predicts far more than the health of your toes.

A monofilament test presses a thin nylon filament against the sole of the foot to find out whether you can feel it. It takes a few seconds at a diabetes checkup, and the answer says far more about the years ahead than most people are ever told.

In the video Pain Is Not a Diagnosis, from The Pained Brain by Dr. Gurpreet Singh Padda, MD, MBA, MHP, and Dr. KrisJay Fucanan, MD, pain is treated as an alarm whose whole job is to send you looking for a cause. A foot that stops feeling is the mirror image of that idea: the alarm goes quiet while whatever set it off keeps working.

What does a monofilament test check?

During a routine diabetes foot exam, a clinician touches a 10 g filament to several spots on each foot and asks whether you notice it. A vibrating tuning fork is often used as well. Both are quick, and both answer one narrow question: does pressure or vibration register at that spot on that day.

That question matters, but it is not the only one. The nerves of the foot are not a single wire. Some carry touch and position, others run the sweat glands and the tiny blood vessels of the skin. A filament that you feel clearly is good news about one kind of fiber. It is not a full report on the others, and it says nothing about blood flow. The difference between those fiber types is covered in small-fiber versus large-fiber neuropathy.

What does an abnormal monofilament test mean?

The best long view comes from a Scottish community cohort of 1,193 people with diabetes who could walk and had no foot ulcer when the study began. At the start, 22.3 percent could not feel the filament, and their average age was 70.5. Over the next ten years, failing the filament test carried 2.739 times the hazard of a first foot ulcer, after adjustment, and failing the tuning fork carried 2.287 times.

Then came the number that rarely reaches the exam room. Of the people who could not feel the filament, 54.9 percent had died within ten years. Of those who could, 37.2 percent had. The study was observational, so it cannot prove that numbness causes an early death; it shows which feet, and which people, carry the risk.

The extreme version makes the same point. Children born unable to feel pain at all are not spared suffering. In a ten-year study of 63 such patients, there were 1,459 documented infections and nine deaths, in a group whose oldest member was 33. The warning system is protective. When it fails, the damage simply goes unannounced.

A system built to quiet the alarm

For roughly two decades, the consensus in pain care, Dr. Padda’s own specialty included, held that lowering the number on the pain scale was the goal in itself. In 1999 the Veterans Health Administration made pain the fifth vital sign. When researchers reviewed 600 visits before and after, none of the quality measures improved, and 52 percent of patients who reported substantial pain received no new therapy at that visit. The number was recorded; the cause was not pursued.

The incentives pushed the same way. In one survey, 83 percent of academic pain-center leaders reported pressure from administrators over patient satisfaction scores. On that kind of scoreboard, a foot that no longer hurts looks like a success. Physiologically, a foot that has gone quiet may be the one in trouble.

Is loss of feeling in the feet linked to circulation and diabetes?

Nerve loss rarely arrives alone. The first companion is circulation. In a national register comparing 3,397 people with diabetes and Charcot foot, a destructive joint condition of the insensate foot, against 27,662 matched controls, hardened arteries were the strongest measured risk, with odds of 8.60 in type 2 diabetes. That register held no nerve data, so it cannot link numbness and blood flow directly. It does say the arteries belong in the same examination as the nerves.

The second companion is the metabolic state underneath, and it is often unmeasured. When one joint replacement program checked the blood sugar of every incoming patient, more than half turned out to have diabetes or prediabetes, and among the people with diabetes, 40.9 percent were hearing it for the first time. Nerves and vessels were absorbing that damage long before anyone had a diagnosis to write down. Guidelines have not closed that gap: the 2022 federal opioid-prescribing guideline runs 95 pages and never mentions A1c or insulin.

What Measura can measure in the same person

Measura [Cardiometabolic and Autonomic Health Analysis] is a measurement service rather than a treatment service. It gathers objective numbers and reports them to your physician, who interprets them alongside your exam. For a foot that has started to go numb, four measurements add what a filament cannot ask.

• Sudomotor testing. Sweat-gland function in the small nerve fibers of the hands and feet, a different nerve population from the one a filament checks.
• Ankle-brachial index. Blood pressure at the ankle, or at the toe, compared with the arm, to show whether flow to the legs is reduced. A normal value has limits, explained in why a normal ankle-brachial index can be misleading.
• Pulse volume recording. The shape of the pulse wave along each segment of the leg, which helps locate where flow changes.
• Laboratory panels. The glucose, A1c and wider metabolic picture behind the nerve and vessel findings.

None of these replaces the filament exam or diagnoses a condition on its own. They turn one yes-or-no answer into a description of nerves, vessels and metabolism in the same foot.

What should you ask your doctor about a monofilament test?

Start with the simple record. If you have diabetes or prediabetes, ask whether a filament and tuning fork check was done, what the result was, and whether it is written in your chart. If you could not feel the filament, ask what that means not only for foot care but for your heart and blood vessels. Ask whether small-fiber and circulation testing would add information. And if nobody has ever checked your A1c, ask for it; in one screening study, prediabetes began at 5.7 percent and diabetes at 6.5 percent.

Unmeasured is unmanaged. Nothing here is a reason to change a medication, and every result belongs with your physician. The studies behind each number, with their limits, are in the Chapter 2 supplement. The metabolic side of the same argument, including the insulin number most people never see, is in the article on the fasting insulin test.

Frequently asked questions

References

• Mohammed, S. A., Crawford, F., Cezard, G. I., & Papathomas, M. (2023). The 10-year follow-up of a community-based cohort of people with diabetes: The incidence of foot ulceration and death. Endocrinology, Diabetes & Metabolism, 7(1), e459. https://doi.org/10.1002/edm2.459
• Klaitman, S. S., Ling, G., Kristal, E., David, O., Elamour, S., Hershkovitz, E., & Ling, E. (2024). Living without pain: A 10-year study of congenital insensitivity to pain with anhidrosis. Pediatric Research, 97(7), 2443–2448. https://doi.org/10.1038/s41390-024-03565-x
• Tsatsaris, G., Rajamand Ekberg, N., Fall, T., & Catrina, S.-B. (2024). Risk factors for Charcot foot development in individuals with diabetes mellitus. Diabetologia, 67(12), 2702-2710. https://doi.org/10.1007/s00125-024-06271-9
• Mularski, R. A., White-Chu, F., Overbay, D., Miller, L., Asch, S. M., & Ganzini, L. (2006). Measuring pain as the 5th vital sign does not improve quality of pain management. Journal of General Internal Medicine, 21(6), 607–612. https://doi.org/10.1111/j.1525-1497.2006.00415.x
• Gonnella, J. C., Abd-Elsayed, A., & Kohan, L. (2020). Patient Satisfaction in Academic Pain Management Centers: How Do We Compare? Current Pain and Headache Reports, 24(12), 76. https://doi.org/10.1007/s11916-020-00910-7
• Shohat, N., Goswami, K., Tarabichi, M., Sterbis, E., Tan, T. L., & Parvizi, J. (2018). All Patients Should Be Screened for Diabetes Before Total Joint Arthroplasty. The Journal of Arthroplasty, 33(7), 2057–2061. https://doi.org/10.1016/j.arth.2018.02.047
• Dowell, D., Ragan, K. R., Jones, C. M., Baldwin, G. T., & Chou, R. (2022). CDC Clinical Practice Guideline for Prescribing Opioids for Pain – United States, 2022. MMWR. Recommendations and Reports, 71(3), 1–95. https://doi.org/10.15585/mmwr.rr7103a1

Related reading

• Fasting Insulin Test: What a Normal A1c Can Hide When You Hurt
• What Does Degenerative Disc Disease Mean for Your Numbers?
• Sudomotor Testing

Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, medical director of Measura. Last reviewed September 12, 2026.