Effect of TENS on Sensory Parameters in Diabetic Polyneuropathy

NCT07807748 | Completed

• 1 other identifier: AKDENIZ-KAEK-402
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

Diabetic polyneuropathy is a common complication of diabetes that damages the nerves of the feet and legs. Besides causing pain, it gradually reduces the ability to feel light touch on the sole of the foot. This loss of protective sensation is important because it removes the warning signal that normally prevents unnoticed injuries, which can lead to foot ulcers. Transcutaneous electrical nerve stimulation (TENS) is a non-drug treatment that delivers mild electrical currents through the skin using surface electrodes. It is inexpensive, widely available, and generally well tolerated. Most previous studies of TENS in diabetic polyneuropathy have looked at whether it relieves pain. Far less is known about whether it affects touch sensation, and whether the frequency of the stimulation matters. This study compares three groups of patients with long-standing diabetic polyneuropathy. One group receives high-frequency TENS (100 Hz), one receives low-frequency TENS (5 Hz), and one receives sham stimulation at an intensity too low to have a treatment effect. Treatment is given five days a week for eight weeks, with electrodes placed on the calf and the sole of the foot. The main measure is the lightest touch a participant can feel on the big toe, tested with Semmes-Weinstein monofilaments before and after the eight-week period. Additional measures include electrical and pressure pain thresholds and questionnaires on pain, mood, and quality of life. Participants and the researchers performing the assessments do not know which group each participant is in.

Conditions

Diabetic Neuropathies; Diabetic Neuropathy, Painful; Peripheral Nervous System Diseases

Outcome Measures

Primary Outcomes (1)

• Tactile detection threshold at the plantar great toe

  Cutaneous touch sensation assessed with Semmes-Weinstein monofilaments (index 1.65-6.65) applied to the plantar surface of the right great toe, with the corresponding buckling force recorded in grams. A higher value indicates a more impaired (less sensitive) threshold. All measurements were obtained by a single investigator blinded to group allocation.

  Baseline and within one week after the end of the eight-week intervention period

Secondary Outcomes (8)

• Electrical pain detection threshold (ePDT)

  Baseline and within one week after the end of the eight-week intervention period

• Electrical pain tolerance threshold (ePTT)

  Baseline and within one week after the end of the eight-week intervention period

• Nociceptive flexion reflex (RIII) threshold

  Baseline and within one week after the end of the eight-week intervention period

• Pressure pain threshold (PPT)

  Baseline and within one week after the end of the eight-week intervention period

• Pressure pain tolerance threshold (PPTO)

  Baseline and within one week after the end of the eight-week intervention period

Study Arms (3)

High-Frequency TENS

EXPERIMENTAL

Conventional high-frequency TENS delivered at 100 Hz with a pulse width of 200 microseconds for 30 minutes per session. One electrode was placed on the calf and one on the plantar surface of the foot. A zero-direct-current, asymmetric biphasic rectangular waveform was used. Intensity was individually adjusted to each participant's sensory tolerance and maintained at a comfortable level throughout the session. Sessions were delivered five days per week for eight weeks.

Device: High-Frequency TENS

Low-Frequency TENS

EXPERIMENTAL

Low-frequency TENS delivered at 5 Hz with a pulse width of 175 microseconds for 15 minutes per session. One electrode was placed on the calf and one on the plantar surface of the foot. A zero-direct-current, asymmetric biphasic rectangular waveform was used. Intensity was individually adjusted to each participant's sensory tolerance and maintained at a comfortable level throughout the session. Sessions were delivered five days per week for eight weeks.

Device: Low-Frequency TENS

Sham TENS

SHAM COMPARATOR

Sham stimulation delivered at a sub-therapeutic intensity (approximately 2-3 mA) insufficient to produce a physiological effect, with all other aspects of the procedure identical to the low-frequency arm, including electrode placement, session structure, and schedule. Sessions were delivered five days per week for eight weeks.

Device: Sham TENS

Interventions

High-Frequency TENS DEVICE

Transcutaneous electrical nerve stimulation delivered with a dual-channel PRIMERA TENS/NMES stimulator (DJO, LLC, USA) using standard 2-inch self-adhesive electrodes, one placed on the calf and one on the plantar surface of the foot. Stimulation was delivered at 100 Hz with a pulse width of 200 microseconds for 30 minutes per session, using a zero-direct-current, asymmetric biphasic rectangular waveform. Intensity was individually adjusted to each participant's sensory tolerance. Sessions were delivered five days per week for eight weeks.

Also known as: HF-TENS; Conventional TENS

High-Frequency TENS

Low-Frequency TENS DEVICE

Transcutaneous electrical nerve stimulation delivered with the same device, electrode type, and electrode placement as the high-frequency arm. Stimulation was delivered at 5 Hz with a pulse width of 175 microseconds for 15 minutes per session, using a zero-direct-current, asymmetric biphasic rectangular waveform. Intensity was individually adjusted to each participant's sensory tolerance. Sessions were delivered five days per week for eight weeks.

Also known as: LF-TENS; Acupuncture-like TENS

Low-Frequency TENS

Sham TENS DEVICE

Sham stimulation delivered with the same device, electrode type, and electrode placement as the active arms, at a sub-therapeutic intensity (approximately 2-3 mA) insufficient to produce a physiological effect. All other aspects of the procedure were identical to the low-frequency arm, including session duration and schedule. Sessions were delivered five days per week for eight weeks.

Sham TENS

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Type 1 or type 2 diabetes mellitus
• Clinically confirmed diabetic peripheral polyneuropathy of at least five years' duration, diagnosed by an endocrinologist during routine outpatient follow-up on the basis of distal symmetric sensory symptoms together with abnormal bedside sensory testing
• Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) score of 9 or above
• Standardized Mini-Mental State Examination score above 24
• Glycated haemoglobin (HbA1c) below 8.5%
• Wagner grade 0 feet (intact plantar skin without ulceration)
• Willing to continue prescribed diet and hypoglycaemic treatment unchanged throughout the study

You may not qualify if:

• Use of a cardiac pacemaker
• Alcohol dependence
• Peripheral arterial disease
• Renal failure
• Hepatic failure
• Hypothyroidism
• Vitamin B12 deficiency
• Folate deficiency
• Sarcoidosis
• Active infection
• Malignancy
• Coagulopathy
• Skin lesion, discolouration, or allergic reaction at the electrode sites

Sponsors & Collaborators

• Burdur Mehmet Akif Ersoy University: lead
• Akdeniz University: collaborator

Study Sites (1)

Akdeniz University City:

Antalya, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Diabetic Neuropathies; Peripheral Nervous System Diseases

Condition Hierarchy (Ancestors)

Neuromuscular Diseases; Nervous System Diseases; Diabetes Complications; Diabetes Mellitus; Endocrine System Diseases

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 2, 2026
• First Posted: September 8, 2026
• Study Start: September 6, 2021
• Primary Completion: September 6, 2021
• Study Completion: November 1, 2021
• Last Updated: September 21, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: Beginning 6 months after publication of the main results and ending 5 years thereafter.
• Access Criteria: Data will be made available to qualified researchers whose proposed use has been approved by the study investigators, for analyses aimed at achieving aims specified in a methodologically sound proposal. Requests should be directed to the corresponding author and will require a signed data access agreement.

Locations

TU (1)