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PubMed This is a summary of 19 peer-reviewed journal articles Updated
Endocrinology

Diagnostics & Understanding Your Tests

At a Glance

For people with diabetes, standard Ankle-Brachial Index (ABI) tests can falsely appear normal due to calcified leg arteries. The Toe-Brachial Index (TBI) is a more accurate diagnostic tool because toe arteries resist calcification, providing a reliable measure of your peripheral blood flow.

Navigating the world of vascular testing can be confusing, especially when tests that work for most people don’t work the same way for those with diabetes. Empowering yourself with an understanding of these tools allows you to ensure your care team is getting the most accurate picture of your “plumbing.”

The Standard Test: Ankle-Brachial Index (ABI)

The Ankle-Brachial Index (ABI) is the most common screening tool for peripheral artery disease. It is a simple ratio calculated by comparing the blood pressure at your ankle to the blood pressure in your arm [1].

  • Normal: 0.9 to 1.3.
  • Abnormal (PAD): Below 0.9 [2].
  • The “False Normal” Trap: In many people with diabetes, the arteries in the lower leg become stiff and calcified (a condition called Mönckeberg’s sclerosis). These “stiff pipes” cannot be compressed by a standard blood pressure cuff, leading to an artificially high reading of over 1.3 [3][4]. If your score is high or “normal” but you still have symptoms, the ABI may be hiding a serious blockage [5].

The Gold Standard for Diabetes: Toe-Brachial Index (TBI)

Because the tiny arteries in your toes are usually less affected by calcification than the larger ones in your ankle, the Toe-Brachial Index (TBI) is a much more reliable test for patients with diabetes [6][7]. A small cuff is placed around your big toe to measure the pressure there.

  • Diagnostic Threshold: A TBI score of less than 0.7 (or sometimes 0.6) is generally considered the optimal marker for diagnosing PAD in the diabetic population [8][9].

Beyond Pressure: Advanced Imaging

If your pressure tests indicate a problem, your doctor may order imaging to “see” exactly where the blockages are located:

  • Duplex Ultrasound (DUS): This non-invasive test uses sound waves to create a map of your blood flow. It is often the first choice for “arterial mapping” of the vessels below the knee [10][11].
  • CT Angiography (CTA) or MR Angiography (MRA): These provide highly detailed, 3D views of your arteries [12]. They are especially helpful if your doctor is planning a procedure to restore blood flow [13]. Note that these tests often require contrast dye. If you have diabetes and diminished kidney function, discuss this with your doctor as the dye can affect your kidneys.
  • Digital Subtraction Angiography (DSA): This is the “gold standard” but is invasive. A specialist inserts a catheter and uses dye to get the most precise view of the blockages [10].

Checklist: What a Complete Evaluation Looks Like

A single test is rarely enough to manage diabetic peripheral angiopathy. A comprehensive vascular evaluation should include:

  1. Vascular Pressure Tests: Both ABI and TBI, especially if the ABI is above 1.3 [14][6].
  2. Physical Exam: A check for “pedal pulses” (pulses in the foot) and a visual inspection for color changes or hair loss [15].
  3. Neurological Assessment: A test for Loss of Protective Sensation (LOPS) to see if neuropathy is present [16][17].
  4. Risk Stratification: Use of the WIfI system to grade the severity of any wounds, ischemia (lack of blood flow), and infection [18].
  5. Skin Assessment: A check for any sores, calluses, or “silent” injuries that aren’t healing [19].

Return to Home Page

Common questions in this guide

Why might an ABI test show normal results even if I have poor blood flow?
In many people with diabetes, leg arteries become stiff and calcified, a condition called Mönckeberg's sclerosis. A standard blood pressure cuff cannot compress these stiff arteries, which can lead to an artificially high or 'false normal' ABI reading even if there are severe blockages.
What is the difference between an ABI and a TBI test?
The Ankle-Brachial Index (ABI) measures blood pressure at the ankle, which can be thrown off by arterial calcification in diabetes. The Toe-Brachial Index (TBI) measures pressure in the big toe, where the tiny arteries are less likely to calcify, making it a much more accurate test for people with diabetes.
What imaging tests are used to find blockages in my legs?
Doctors typically start with a non-invasive Duplex Ultrasound to map blood flow below the knee. If more detail is needed or a procedure is being planned, they may order advanced imaging like CT Angiography, MR Angiography, or Digital Subtraction Angiography to see the exact location of the blockages.
What is a WIfI score?
The WIfI system is a grading tool used by vascular specialists to classify the severity of diabetic foot issues. It evaluates three critical factors—Wounds, Ischemia (lack of blood flow), and foot Infection—to determine your overall risk of limb loss and guide treatment.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my ABI score in the 'non-compressible' range (above 1.3), and if so, can we perform a TBI?
  2. 2.If my TBI is below 0.7, what does that tell us about the risk of me developing a non-healing ulcer?
  3. 3.Should we use Duplex Ultrasound to 'map' the arteries below my knee to see if there are specific blockages?
  4. 4.Does my medical record include a 'WIfI' score to help classify my risk of limb loss?
  5. 5.Can we also check for 'Loss of Protective Sensation' (LOPS) today to see if neuropathy is masking my vascular symptoms?

Questions For You

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References

References (19)
  1. 1

    The accuracy of an oscillometric ankle-brachial index in the diagnosis of lower limb peripheral arterial disease: A systematic review and meta-analysis.

    Herráiz-Adillo Á, Cavero-Redondo I, Álvarez-Bueno C, et al.

    International journal of clinical practice 2017; (71(9)) doi:10.1111/ijcp.12994.

    PMID: 28851093
  2. 2

    How to perform the ankle brachial index test in clinical practice.

    Organ NM, Harrison C

    The Medical journal of Australia 2017; (207(2)):60-61 doi:10.5694/mja17.00112.

    PMID: 28701124
  3. 3

    Falsely normalized ankle-brachial index despite the presence of lower-extremity peripheral artery disease: two case reports.

    Maruhashi T, Matsui S, Yusoff FM, et al.

    Journal of medical case reports 2021; (15(1)):622 doi:10.1186/s13256-021-03155-z.

    PMID: 34920746
  4. 4

    Screening of peripheral arterial disease in primary health care.

    Tóth-Vajna Z, Tóth-Vajna G, Gombos Z, et al.

    Vascular health and risk management 2019; (15()):355-363 doi:10.2147/VHRM.S208302.

    PMID: 31686829
  5. 5

    Critical analysis and limitations of resting ankle-brachial index in the diagnosis of symptomatic peripheral arterial disease patients and the role of diabetes mellitus and chronic kidney disease.

    AbuRahma AF, Adams E, AbuRahma J, et al.

    Journal of vascular surgery 2020; (71(3)):937-945 doi:10.1016/j.jvs.2019.05.050.

    PMID: 31471230
  6. 6

    Peripheral Arterial Disease Located in the Feet of Patients With Diabetes and Foot Ulceration Demands a New Approach to the Assessment of Ischemia.

    Manu CA, Freedman B, Rashid H, et al.

    The international journal of lower extremity wounds 2022; (21(4)):397-404 doi:10.1177/1534734620947979.

    PMID: 32806976
  7. 7

    Toe brachial index and not ankle brachial index is appropriate in initial evaluation of peripheral arterial disease in type 2 diabetes.

    Singhania P, Das TC, Bose C, et al.

    Diabetology & metabolic syndrome 2024; (16(1)):52 doi:10.1186/s13098-024-01291-2.

    PMID: 38414018
  8. 8

    Diagnostic thresholds for absolute systolic toe pressure and toe-brachial index in diabetic foot screening.

    Ng CG, Cheong CYW, Chan WC, et al.

    Annals of the Academy of Medicine, Singapore 2022; (51(3)):143-148 doi:10.47102/annals-acadmedsg.2021384.

    PMID: 35373237
  9. 9

    Toe- Brachial Index: Utility, Futility, and Diagnostic Criteria.

    Casanegra AI, Liedl DA, McCarter C, et al.

    Angiology 2026; (77(2)):221-228 doi:10.1177/00033197251313863.

    PMID: 39840433
  10. 10

    Current Opinion on Diagnosis of Peripheral Artery Disease in Diabetic Patients.

    Ghirardini F, Martini R

    Medicina (Kaunas, Lithuania) 2024; (60(7)) doi:10.3390/medicina60071179.

    PMID: 39064610
  11. 11

    Concordance between preoperative ultrasound arterial mapping in the femoropopliteal and distal sector and intraoperative angiography.

    Morata Barrado PC, Muela Méndez M, Recover Palenzona AE, et al.

    Journal of ultrasound 2025; (28(1)):101-106 doi:10.1007/s40477-024-00967-9.

    PMID: 39543077
  12. 12

    Application opportunity of Doppler ultrasound combined with CT angiography in diabetic lower extremity arterial disease and the analysis of the risk factors.

    Zhang S, Wu Y, Guo Y, et al.

    Frontiers in endocrinology 2023; (14()):1257241 doi:10.3389/fendo.2023.1257241.

    PMID: 38352247
  13. 13

    Vertebral Artery Stenosis: A Narrative Review.

    Burle VS, Panjwani A, Mandalaneni K, et al.

    Cureus 2022; (14(8)):e28068 doi:10.7759/cureus.28068.

    PMID: 36127977
  14. 14

    Relationship between ankle Brachial Index and Pattern of Coronary Artery Disease: An observational study.

    Rani EP, Ramamoorthy L, Satheesh S

    Journal of family medicine and primary care 2020; (9(9)):5079-5080 doi:10.4103/jfmpc.jfmpc_647_20.

    PMID: 33209853
  15. 15

    Development and Validation of a Risk Prediction Model for Foot Ulcers in Diabetic Patients.

    Lv J, Li R, Yuan L, et al.

    Journal of diabetes research 2023; (2023()):1199885 doi:10.1155/2023/1199885.

    PMID: 36846514
  16. 16

    Management of diabetic foot ulcers in the community: an update.

    Levy N, Gillibrand W

    British journal of community nursing 2019; (24(Sup3)):S14-S19 doi:10.12968/bjcn.2019.24.Sup3.S14.

    PMID: 30817189
  17. 17

    Prevalence, Clinical Presentation, and Factors Associated With Diabetic Foot Ulcer in Two Regional Hospitals in Cameroon.

    Tindong M, Palle JN, Nebongo D, et al.

    The international journal of lower extremity wounds 2018; (17(1)):42-47 doi:10.1177/1534734618764252.

    PMID: 29564949
  18. 18

    Pedal arterial calcification score is associated with the risk of major amputation in chronic limb-threatening ischemia.

    Liu IH, Wu B, Krepkiy V, et al.

    Journal of vascular surgery 2022; (75(1)):270-278.e3 doi:10.1016/j.jvs.2021.07.235.

    PMID: 34481900
  19. 19

    Prevalence of Diabetic Foot Ulcer and Associated Factors among Adult Diabetic Patients on Follow-Up Clinic at Jimma Medical Center, Southwest Ethiopia, 2019: An Institutional-Based Cross-Sectional Study.

    Abdissa D, Adugna T, Gerema U, Dereje D

    Journal of diabetes research 2020; (2020()):4106383 doi:10.1155/2020/4106383.

    PMID: 32258165

This page provides educational information about diagnostic tests for diabetic peripheral angiopathy. It is not a substitute for professional medical advice, diagnosis, or the interpretation of your specific test results by a qualified vascular specialist.

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