Why Ankle Pressures Can Look Normal With Diabetes: Toe Pressures Explained

Perhaps you were told your circulation is fine because your ankle numbers were normal, yet a sore on your foot isn’t closing. That mismatch is a known weak spot: the US guideline on peripheral artery disease notes that the ankle test has real limits with diabetes and chronic kidney disease.⁠^[1] For every circulation test in one place, see circulation tests for foot wounds; for the warning signs, see poor circulation in the feet (external site) from our parent practice.

What the ankle test measures

The ABI compares the blood pressure at your ankle with the pressure in your arm, using a blood pressure cuff and a Doppler device that picks up blood flow.⁠^[4,1] A result of 0.90 or lower is abnormal, 1.00–1.40 is normal, and above 1.40 is labeled “noncompressible.”⁠^[1]

It is still the starting point for diagnosing peripheral artery disease (PAD). In people with PAD symptoms, it correctly flags 69%–79% of those whose imaging shows a significant narrowing, and it does less well when diabetes is present.⁠^[1]

Why the ankle reading can mislead with diabetes

Stiff, calcified arteries. Calcium deposits in the artery wall, called medial arterial calcification, are common with diabetes and often go along with nerve damage. They raise ankle pressures and, to a lesser degree, toe pressures.⁠^[2] A stiffened artery is hard for the cuff to compress, so the reading climbs.⁠^[5,2] With diabetes or kidney disease, these stiff arteries below the knee can push the ABI above 1.40 even when imaging confirms significant blockages.⁠^[1]

Where the blockages sit. With diabetes, narrowings tend to form in the arteries below the knee, which run side by side down the leg. The standard ABI uses only the higher ankle pressure, so a good reading from one open artery can hide blocked ones beside it.⁠^[5] In 187 legs that had both an ABI and an angiogram at a Belgian diabetic foot clinic, the ABI could be calculated in only 65.7%, matched the angiogram poorly, and underestimated the disease it showed.⁠^[5]

Nearly one in four people with chronic limb-threatening ischemia, the advanced stage of PAD that puts the foot at risk, has an ABI between 0.90 and 1.40. Among people at that stage whose toe pressures are abnormal, only 58% also have an abnormal ABI.⁠^[1] At a Danish hospital, 20.5% of 3,739 people referred for known or suspected PAD had a low toe-brachial index but a normal ABI, and their other health problems resembled those of people with a low ABI.⁠^[6] A study written as a guide for foot and ankle surgeons warned that a falsely normal ABI can lead a surgeon to assume blood flow is fine.⁠^[3]

What a toe pressure adds

The small arteries of the toes are rarely too stiff to compress, so a toe pressure can be used when the ankle reading can’t be trusted.⁠^[1,7] The test measures the blood pressure in your big toe. Divided by the arm pressure, it gives the toe-brachial index (TBI), and a TBI of 0.70 or lower is considered abnormal.⁠^[4,1]

Toe pressures also look at the forefoot and toes, where most diabetic foot ulcers form.⁠^[2] For anyone with diabetes and a foot ulcer or gangrene, the international guideline recommends Doppler waveforms, the ABI and the TBI together, because no single test has been shown to be ideal and no value can rule PAD out.⁠^[2] Readings are taken in a warm room, because cold narrows the arteries.⁠^[1]

What the numbers say about healing

In a systematic review of 28 studies in people with diabetic foot ulcers, by members of the international guideline panel, a toe pressure of 30 mmHg or more was linked with a moderate to large rise in the chance of healing, while an ABI of 0.9 or more did not make healing any more likely. An ABI under 0.5 made non-healing moderately more likely, and one under 0.4 was tied to the largest rise in the chance of a major amputation.⁠^[8]

The guideline puts figures on the toe reading: 30 mmHg or more raises the likelihood of healing by up to 30%, and a lower value raises the likelihood of a major amputation by about 20%.⁠^[2] It also warns that an ABI above 1.3 is linked with more amputations and shorter amputation-free survival, so a “too good” ankle number is a reason to look closer.⁠^[2]

How the results shape wound care and surgery

For a surgical practice, these numbers decide what comes next.

• Before planned foot surgery. Except for emergency surgery to control a severe infection, the guideline says everyone with diabetes who needs foot surgery should first have Doppler waveforms with an ABI and a toe pressure or TBI.⁠^[2] When blood flow is good, we can move ahead with the operation that removes the cause of the wound, such as correcting a deformity or lengthening a tight Achilles tendon (see surgery that takes pressure off ulcers and Achilles lengthening for forefoot ulcers).
• When the readings show ischemia. A toe pressure below 60 mmHg, an ankle pressure below 100 mmHg, missing pulses, or a single-phase (monophasic) or absent Doppler signal call for a vascular specialist’s opinion on restoring blood flow; below 30 mmHg at the toe, that opinion is urgent.⁠^[2] We don’t perform angioplasty or bypass ourselves; we refer you and plan your foot care around the procedure (see restoring blood flow).
• When part of the foot must be removed. Toe pressures help predict whether a toe or partial foot amputation will heal.⁠^[8] In a review of these operations in people with diabetes, healing was reported at average toe pressures of 30 mmHg or more, and in four pooled studies a toe pressure under 30 mmHg roughly doubled the risk of the site not healing (relative risk 2.09).⁠^[9] Together with your vascular specialist, we use these readings to plan a partial foot amputation that has a good chance of healing while keeping as much of your foot as we can. See also transmetatarsal or below-knee amputation.
• When a wound stalls. If a foot ulcer hasn’t shrunk by about half within 4 weeks despite good infection and blood sugar control, wound care and offloading, the guideline says to recheck circulation and consult a vascular specialist.⁠^[2] That checkpoint is one reason early wound care matters.

We do noninvasive circulation testing at our practice and arrange arterial duplex ultrasound or angiography with vascular specialists when more detail is needed. Dr. Efe Ozturk, a Foot and Ankle Surgeon who is board certified in wound care (FAPWH), weighs the results with what he sees in the wound.

Kidney disease and dialysis

The problem is sharper with chronic kidney disease. An international kidney-care panel (KDIGO) notes that kidney disease raises the risk of artery-wall calcification, which can leave the ABI falsely normal or high even with severe PAD, and it advises measuring the toe-brachial index at the same time.⁠^[10] In the study written for foot and ankle surgeons, people on dialysis had 7.3 times the odds of having PAD.⁠^[3] With kidney disease, ask whether a toe pressure was part of your testing; see foot wounds with kidney disease.

Limits of toe pressures

Toe pressures are better, not perfect. The 0.70 cut-off for an abnormal TBI is widely used but isn’t firmly evidence-based.⁠^[7] Across seven studies that checked the TBI against imaging, it detected anywhere from 45% of PAD cases in one study to every case in another.⁠^[11] And in a 2025 review of 35 studies in people prone to calcified arteries, none of the bedside tests, toe pressures included, predicted healing and non-healing well enough on its own.⁠^[12]

So no single reading decides. Infection, the size and depth of the wound and pressure on it all affect healing.⁠^[2] When circulation results look good but a wound still won’t close, we look for other causes; damage to the tiniest blood vessels shouldn’t be blamed until those are ruled out.⁠^[2,1]

Common questions

My ABI was normal. Could my circulation still be poor?

Yes. Nearly one in four people with limb-threatening ischemia has an ABI in the 0.90–1.40 range, and calcified arteries from diabetes or kidney disease make a falsely normal reading more likely.⁠^[1,10] A toe pressure, checked with the ABI and Doppler waveforms, gives a fuller picture.⁠^[2]

What counts as a good toe pressure?

A TBI of 0.70 or lower is abnormal.⁠^[1] For a foot ulcer, a toe pressure of 30 mmHg or more makes healing more likely, while a reading below 30 mmHg points to severe ischemia and calls for an urgent vascular opinion.⁠^[2]

Why was my ABI above 1.40?

It means the ankle arteries are too stiff for the cuff to compress, so the number can’t be relied on and a toe pressure or TBI should be done.⁠^[1]

Can I have foot surgery if my toe pressure is low?

Low readings call for a vascular specialist’s opinion on restoring blood flow first,⁠^[2] and we time planned foot surgery around that. Surgery to control a severe infection is the exception: it doesn’t wait, and its timing is planned urgently with the vascular specialist.⁠^[2]

What if a toe pressure can’t be measured?

That happens after a forefoot amputation, for example. The oxygen level measured through the skin (TcPO2) or a skin perfusion pressure can be used instead.⁠^[2]

The bottom line

With diabetes or kidney disease, a normal ankle-brachial index doesn’t prove your foot has the blood flow it needs to heal. Toe pressures, read with the ABI and Doppler waveforms, give a truer picture and help decide whether the next step is surgery that removes the cause of the wound, restoring blood flow first, or both. If a wound isn’t healing, ask what your toe pressure is.