For physicians

Clinical rationale

The argument is not that these assessments are novel. It is that the physiology they measure deteriorates years before the diagnoses we make from it, and that in a general adult panel abnormality is the rule rather than the exception.

1. The base rate is not what most protocols assume

In the National Health and Nutrition Examination Survey for 2009 to 2016, 12.2% of American adults met a full definition of optimal metabolic health in the National Health and Nutrition Examination Survey for 2009 to 2016 — so roughly 88% of US adults did not when metabolic health was defined by contemporary cut points across waist circumference, fasting glucose and HbA1c, blood pressure, triglycerides and HDL cholesterol, with no medication for any of them. Fewer than one in three normal-weight adults met that definition; the figure fell to 8.0% in overweight adults and 0.5% in adults with obesity.

In the Padda Institute patient population the picture is starker still: fewer than 3% of patients overall, and fewer than 1% of chronic pain patients, meet the same definition of metabolic health. Those are practice-reported figures from our own population, not trial outcomes, and individual results vary.

The operational consequence is straightforward. A screening protocol that triggers on overt abnormality will under-detect, because the interesting population is the one that is still compensating.

2. Small fibers fail before large fibers

Nerve injury associated with impaired glucose tolerance and the metabolic syndrome preferentially affects the small fibers, and nerve conduction studies are relatively insensitive to it — which is why intraepidermal nerve fiber density on skin biopsy is often used to confirm the diagnosis. In practice that means a patient with burning feet and a normal nerve conduction study has usually been tested with the wrong instrument, not reassured.

Electrochemical skin conductance offers a non-invasive route to the same territory. A systematic review identified 24 studies and appraised the method against established reference tests including the quantitative sudomotor axon reflex test, sympathetic skin responses, the thermoregulatory sweat test and skin biopsy.

The American Diabetes Association’s position statement on diabetic neuropathy is explicit that screening should not await symptoms, and that a substantial proportion of distal symmetric polyneuropathy is painless — the patients at highest risk of ulceration are frequently the ones who report the least.

3. A normal ankle-brachial index does not exclude disease

Medial calcification makes ankle vessels resistant to compression, producing a falsely normal or elevated index in a limb with real disease. This is common in long-standing diabetes and in chronic kidney disease — precisely the population being screened. Pulse volume recording and the toe-brachial index do not depend on vessel compressibility, which is why the suite includes all three rather than the index alone.

Peripheral artery disease is the third leading cause of atherosclerotic cardiovascular morbidity after coronary disease and stroke, with an estimated 202 million people affected worldwide in 2010. In the same systematic review, prevalence in the wealthier countries surveyed rose from about 5% at ages 45–49 to about 18% by ages 85–89.

4. Artery and nerve imitate each other

Arterial and autonomic nerve dysfunction are the most frequent complications of diabetes, kidney disease, hepatitis, thyroid failure and aging, and they present with overlapping symptoms. Distinguishing them changes management materially. Testing both in the same sitting is the practical way to do it.

5. Balance is a measurable, high-yield target

35.4% of US adults aged 40 and older — about 69 million people — had vestibular dysfunction on the modified Romberg test in a national survey; the odds were 70% higher among people with diabetes, and symptomatic individuals had a twelve-fold increase in the odds of falling. Falls remain the leading cause of injury and injury death in adults 65 and over: 27.6% reported a fall in the previous year in 2020, and there were 38,742 fall deaths in 2021.

The cognitive and fall prevention pairing follows directly from this.

Where the evidence is thinner, and what that means

Not every assessment in this suite has a large randomized trial behind it as a screening intervention, and it is worth saying so plainly. Two things follow, and neither is a reason to avoid measuring.

First, the trials that do exist have systematically excluded the patients this testing is aimed at. Randomized studies of vascular and neuropathic interventions routinely exclude people with multiple comorbidities, significant obesity, polypharmacy, long symptom duration and prior failed treatment. A clean result in a highly selected population does not transfer automatically, and a null or modest result in that population does not establish that the measurement is useless in patients who were screened out.

Second, several of these are diagnostic measurements rather than interventions, and the appropriate standard for a diagnostic is whether it measures what it claims to measure and whether the result changes management. Both are answerable, and both are addressed on the individual test pages.

For patients: the same subject written for the person having the assessment is at the patient track.

Common questions

What does this add over an annual physical?

Function rather than status: vessel compliance, small-fiber integrity, autonomic reserve and measured metabolic rate are not part of a standard examination. What these assessments add.

Is sudomotor testing a substitute for nerve conduction studies?

No — they measure different fiber populations and answer different questions. Small-fiber versus large-fiber neuropathy.

How do I decide who to send?

There is a defined criteria set applied at intake. Who should have this testing.

What happens to an abnormal result?

It is interpreted in context and, where borderline, repeated before anything is concluded. What a result can and cannot tell you.

References

• Araújo J, Cai J, Stevens J. Prevalence of Optimal Metabolic Health in American Adults: National Health and Nutrition Examination Survey 2009–2016. Metabolic Syndrome and Related Disorders. 2019;17(1):46–52. doi:10.1089/met.2018.0105
• Chowdhury M, Nevitt S, Eleftheriadou A, et al. Cardiac autonomic neuropathy and risk of cardiovascular disease and mortality in type 1 and type 2 diabetes: a meta-analysis. BMJ Open Diabetes Research & Care. 2021;9(2):e002480. doi:10.1136/bmjdrc-2021-002480
• Spallone V, Ziegler D, Freeman R, et al. Cardiovascular autonomic neuropathy in diabetes: clinical impact, assessment, diagnosis, and management. Toronto Consensus Panel on Diabetic Neuropathy. Diabetes/Metabolism Research and Reviews. 2011;27(7):639–653. doi:10.1002/dmrr.1239
• Vlachopoulos C, Aznaouridis K, Stefanadis C. Prediction of cardiovascular events and all-cause mortality with arterial stiffness: a systematic review and meta-analysis. Journal of the American College of Cardiology. 2010;55(13):1318–1327. doi:10.1016/j.jacc.2009.10.061
• Fowkes FGR, Rudan D, Rudan I, et al. Comparison of global estimates of prevalence and risk factors for peripheral artery disease in 2000 and 2010: a systematic review and analysis. Lancet. 2013;382(9901):1329–1340. doi:10.1016/S0140-6736(13)61249-0
• Aboyans V, Criqui MH, Abraham P, et al. Measurement and interpretation of the ankle-brachial index: a scientific statement from the American Heart Association. Circulation. 2012;126(24):2890–2909. doi:10.1161/CIR.0b013e318276fbcb
• Brouwers JJWM, Willems SA, Goncalves LN, Hamming JF, Schepers A. Reliability of bedside tests for diagnosing peripheral arterial disease in patients prone to medial arterial calcification: a systematic review. EClinicalMedicine. 2022;50:101532. doi:10.1016/j.eclinm.2022.101532
• Agrawal Y, Carey JP, Della Santina CC, Schubert MC, Minor LB. Disorders of balance and vestibular function in US adults: data from the National Health and Nutrition Examination Survey, 2001–2004. Archives of Internal Medicine. 2009;169(10):938–944. doi:10.1001/archinternmed.2009.66
• Kakara R, Bergen G, Burns E, Stevens M. Nonfatal and Fatal Falls Among Adults Aged ≥65 Years — United States, 2020–2021. MMWR Morbidity and Mortality Weekly Report. 2023;72(35):938–943. doi:10.15585/mmwr.mm7235a1
• Novak P. Electrochemical skin conductance: a systematic review. Clinical Autonomic Research. 2019;29(1):17–29. doi:10.1007/s10286-017-0467-x
• Vinik AI, Nevoret ML, Casellini C. The new age of sudomotor function testing: a sensitive and specific biomarker for diagnosis, estimation of severity, monitoring progression, and regression in response to intervention. Frontiers in Endocrinology. 2015;6:94. doi:10.3389/fendo.2015.00094
• Carbajal-Ramírez A, Hernández-Domínguez JA, Molina-Ayala MA, Rojas-Uribe MM, Chávez-Negrete A. Early identification of peripheral neuropathy based on sudomotor dysfunction in Mexican patients with type 2 diabetes. BMC Neurology. 2019;19(1):109. doi:10.1186/s12883-019-1332-4
• Castro J, Miranda B, Castro I, de Carvalho M, Conceição I. The diagnostic accuracy of Sudoscan in transthyretin familial amyloid polyneuropathy. Clinical Neurophysiology. 2016;127(5):2222–2227. doi:10.1016/j.clinph.2016.02.013
• Cortez M, Singleton JR, Smith AG. Glucose intolerance, metabolic syndrome, and neuropathy. Handbook of Clinical Neurology. 2014;126:109–122. doi:10.1016/B978-0-444-53480-4.00009-6
• Pop-Busui R, Boulton AJM, Feldman EL, et al. Diabetic Neuropathy: A Position Statement by the American Diabetes Association. Diabetes Care. 2017;40(1):136–154. doi:10.2337/dc16-2042
• ClinicalTrials.gov registry search for interventions matching “Sudoscan,” “electrochemical skin conductance” or “sudomotor,” 41 registered studies, retrieved 20 August 2026. clinicaltrials.gov

Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, medical director of Measura. Last reviewed August 20, 2026.