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A study testing capsaicin patches compared to placebo for patients with painful diabetic nerve damage to assess effects on nerve symptoms and nerve fibers

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study examines painful diabetic peripheral neuropathy, a condition where high blood sugar levels from diabetes mellitus damage nerves in the feet and legs, causing pain, burning sensations, tingling, or numbness. The treatment being tested is Qutenza, which is a patch applied to the skin containing a high concentration of capsaicin, a substance derived from chili peppers. This will be compared to a placebo patch that looks the same but does not contain the active ingredient. The purpose of the study is to evaluate how repeated treatment with the capsaicin patch affects nerve fibers in the skin.

Participants in this study will receive either the capsaicin patch or the placebo patch applied to their skin at different time points during the study. The study will examine changes in nerve fiber density in the skin by taking small skin samples called biopsies. These tiny samples allow researchers to count and measure the nerve fibers under a microscope. The study will also assess changes in pain levels, various symptoms of nerve damage such as burning or tingling sensations, quality of life, and how the skin responds to different sensations like temperature and touch. Additionally, blood flow in the small vessels of the skin and oxygen levels in the tissue will be measured.

The study involves multiple visits to the study center over approximately 35 weeks. During this time, participants will be asked to maintain their current pain and diabetes medications unchanged. Researchers will monitor any side effects or unwanted reactions that may occur during the treatment. The study will also track whether participants need additional pain medication and how often they use it. Various questionnaires and physical tests will be performed throughout the study to measure changes in symptoms and nerve function.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment with capsaicin or placebo patch

    At the start of the trial, a patch will be applied to the skin of your feet. This will be either a capsaicin 8% patch (called Qutenza) or a placebo patch (a patch without active medication). The assignment to one of these treatments will be random, and neither you nor your doctor will know which type of patch you receive.

    The patch is designed to treat pain caused by nerve damage in your feet related to diabetes. Capsaicin is a substance derived from chili peppers that can help reduce nerve pain.

    The patch will be applied to the painful areas of your feet. The application will be performed at the study center.

    During this first treatment, your current pain medications should remain unchanged throughout the study.

  2. Step 2

    Assessment at week 11

    At week 11 after the first treatment, you will attend a study visit.

    During this visit, several assessments will be performed to evaluate changes in your condition. These may include questions about your pain levels, skin tests to check sensation in your feet, and measurements of blood flow in the skin.

    A small skin biopsy may be taken. This involves removing a tiny sample of skin to examine the nerve fibers under a microscope. The biopsy helps measure changes in the small nerve fibers in your skin.

    The assessments will compare your current condition to how you were at the beginning of the study.

  3. Step 3

    Second treatment with capsaicin or placebo patch

    After the week 11 assessment, a second patch treatment will be applied to the same areas of your feet.

    This will be the same type of patch (either capsaicin 8% or placebo) that you received during the first treatment.

    The application procedure will be the same as during the first treatment.

  4. Step 4

    Assessment at week 25

    At week 25, you will return for another study visit.

    Similar assessments will be performed as at week 11, including questions about your pain, sensory tests, and measurements of skin blood flow.

    These assessments will help determine how your symptoms have changed over time.

  5. Step 5

    Final assessment at week 35

    At week 35, you will attend the final study visit.

    Comprehensive assessments will be performed, including all previous measurements of pain levels, sensory function, and skin blood flow.

    Additional skin biopsies will be taken to examine the nerve fibers and blood vessels in your skin. These samples will be analyzed to measure changes in nerve fiber density and other markers of nerve health.

    The results from this final visit will be compared to your condition at the beginning of the study and at previous visits to determine the overall effects of the treatment.

  6. Step 6

    Ongoing monitoring throughout the study

    Throughout the entire study period, any side effects or health changes you experience will be recorded and monitored.

    You may be asked to complete questionnaires about your pain intensity, quality of life, and specific symptoms such as burning sensations, shooting pains, or abnormal sensations in your feet.

    If your pain becomes difficult to manage, rescue medication may be available. The use of any additional pain medication will be recorded.

    Your blood sugar control will be monitored, and your HbA1c (a measure of average blood sugar levels over the past few months) should remain below 10% during the study.

Who can join the trial?

13 criteria

  • You must sign and date a written informed consent form
  • You must be willing to keep your current pain medication the same throughout the study
  • You must be able and willing to attend all study center visits and complete study procedures for the entire study duration
  • If you are a woman who can become pregnant, you must be willing to use acceptable birth control methods during the treatment phase
  • If you are a woman who can become pregnant, you must have a negative urine pregnancy test at the screening visit
  • You must have diabetes mellitus, which is a condition where your blood sugar levels are too high, diagnosed according to established criteria and lasting at least 1 year
  • You must be between 18 and 80 years old
  • You must have painful diabetic sensorimotor polyneuropathy, which is nerve damage in your body caused by diabetes that affects both sensation and movement, lasting at least 6 months as determined by the study doctor
  • You must have pain in your feet or ankles caused by this nerve damage, with an average or maximum pain score of at least 4 points on a scale from 0 to 10 within 7 days before screening
  • You must have abnormal sensations such as dysesthesia, which is an unpleasant or painful feeling when touched, or paresthesia, which is tingling or pins and needles sensation in your lower limbs caused by nerve damage, lasting at least 6 months
  • You must have at least one of the following: reduced or absent reflexes, sensation problems, abnormal nerve conduction test results, abnormal sensory testing results, or reduced nerve fiber density in your lower limbs
  • Your HbA1c, which is a blood test that shows your average blood sugar levels over the past 2 to 3 months, must be less than 10% at screening
  • If applicable, your diabetes medications and pain medications must have been stable for at least 4 weeks before screening as determined by the study doctor

Who cannot join the trial?

1 criterion

  • The study does not provide specific exclusion criteria in the available information, which means the detailed reasons why someone cannot participate are not listed in the source data provided.
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Investigated drugs

  • Qutenza

    is a skin patch that contains a high concentration of capsaicin, which is a substance derived from chili peppers. This patch is applied to the skin to help reduce nerve pain in people with diabetic peripheral neuropathy, a condition where diabetes damages nerves and causes pain, tingling, or numbness, usually in the feet and legs. The patch works by affecting the nerve fibers in the skin that send pain signals to the brain.

  • Placebo patch

    is a patch that looks identical to the Qutenza patch but does not contain any active medication. It is used in this study to compare whether the real treatment works better than no treatment at all.

What is already known about the treatment

Qutenza – Qutenza is a skin patch containing 8% capsaicin, which is a natural substance found in chili peppers, applied directly to the painful area of the skin by a healthcare professional. It is used to treat nerve pain caused by diabetes affecting the feet and legs, known as diabetic peripheral neuropathy. The medication works by initially activating and then reducing the activity of pain receptors in the nerve endings under the skin, which decreases the transmission of pain signals to the brain. Qutenza belongs to a class of medications called topical analgesics and is currently being studied in clinical trials to evaluate its effectiveness in improving nerve fiber health and reducing neuropathic pain symptoms.

Investigated diseases

Painful Diabetic Peripheral Neuropathy – This is a nerve disorder that occurs as a complication of diabetes. High blood sugar levels over time can damage the peripheral nerves, which are the nerves outside the brain and spinal cord. The condition typically affects the feet and legs first, but can also involve the hands and arms. People with this condition experience pain, burning sensations, tingling, or numbness in the affected areas. The nerve damage progresses gradually and can also cause sensitivity to touch and difficulty sensing temperature changes. This disorder develops when diabetes is not well controlled over an extended period.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-523597-17-00Protocol codeQ-HEAL-001Estimated enrolment40 patientsSponsorDeutsche Diabetes Forschungsgesellschaft e.V.

sourced from the EU Clinical Trials Register and site verification

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