The Biodex is a computer-assisted device with a movement system capable of providing surface inclinations ranging from 360 degrees to 20 degrees. It allows movement in anterior/posterior and mediolateral planes. The device has 12 levels of difficulty, where level 12 represents the highest stability and level 1 represents the lowest stability. It can be used for balance training with different therapy protocols and includes standardized programming systems for evaluating both static and dynamic balance. It provides numerical data for key parameters such as balance, fall risk, and proprioception. In this study, patients will be assessed using the fall risk test and postural stability evaluation test protocols on the Biodex balance system. All participants will be trained and familiarized with the system before the test.

Postural Stability Test: The difficulty level will be set to 8. Fall Risk Test: The difficulty level will progressively decrease from 6 to 2.

The Douleur Neuropathique 4 (DN4) pain scale score will be used to screen for diabetic peripheral neuropathic pain. The DN4 scale consists of 10 questions, 7 of which inquire about symptoms, and 3 that assess the patient's clinical examination for neuropathy. The symptoms assessed include a burning sensation, pain from cold, electric shock sensations, tingling, pins and needles, numbness, and itching. The sensory exams assess touch hypoesthesia, pin-prick hypoesthesia, and brush allodynia. Each "yes" response to a question receives 1 point. To calculate the total score, points obtained from the symptom inquiry and clinical examination are added together. The maximum total score is 10, and a score of 4 or higher is considered indicative of neuropathic pain

The numeric pain scale will be used to assess the intensity of neuropathic pain. The patient is asked to provide a value between 0 and 10 to indicate the intensity of their pain. Higher scores are associated with an increase in pain severity.

The Toronto Clinical Neuropathy Score (TCNS) will be used to assess the severity of Diabetic Peripheral Polyneuropathy (DPPN). The Turkish version of the Toronto clinical scoring system is a reliable and valid tool for assessing polyneuropathy in Turkish-speaking patients. The TCNS is preferred in clinical studies because of its ease of use, patient acceptability, ability to classify the severity of DPPN, and its representation of clinical changes related to the progression of DPPN. The scale consists of three sections: symptom scores, sensory test scores, and reflex scores.The first section includes scoring symptoms in the upper and lower extremities .The second section includes scoring the bilateral Achilles and patellar reflexes. The third section involves scoring the sensation in the toe. The total score ranges from a minimum of 0 (no neuropathy) to a maximum of 19 points.

Six-Minute Walk Test (6MWT) is a commonly used test to assess functional capacity. The test area should be a corridor with a minimum length of 30 meters, flat, and firm surface. The corridor should be marked every 3 meters. Turnaround points are indicated with objects such as orange traffic cones. A line is drawn for the start and end of the test. Recommended materials for the test include a stopwatch, a device to count laps, cones to mark turning points, a chair placed within easy reach, oxygen support (to be given if necessary), and a blood pressure cuff. The patient should wear comfortable clothing and shoes suitable for walking. They can use any walking aids such as crutches or a walker. Medications or treatments should be taken as usual. The patient should have had a light meal before the test and should not have engaged in heavy physical activity within the 2 hours preceding the test. There should be no warm-up period before the test.

The SF-12 Quality of Life Scale will be calculated using an online calculator tool, providing two types of scores: physical and mental scores.

The IPAQ scale was developed to address the general health problem of insufficient physical activity, which necessitates large population studies and allows for cross-country comparisons. Validity studies conducted across multiple countries have proven that this questionnaire is valid and reliable. This survey assesses individuals based on the types of physical activities they perform in their daily lives. The questions asked pertain to the time spent physically active over the past 7 days.

Vibration sense will be assessed using a traditional 128 Hz tuning fork. When the stem of a 128 Hz tuning fork is placed on the dorsal aspect of the interphalangeal joint of the hallux, a healthy person can feel the vibration as long as it continues (15-20 seconds). In conditions leading to peripheral nerve damage (such as polyneuropathy), vibration sense is impaired. The examiner holds the proximal end of the tuning fork with one hand, while the distal end is struck strongly against the palm of the examiner's other hand. The examiner should try to strike the tuning fork with consistent force for each assessment. After striking, the tuning fork is placed just proximal to the nail bed, on the dorsal aspect of the distal phalanx of the hallux.Before applying the tuning fork, the participant is instructed to verbally respond with "yes" if they can initially feel the vibration, and they should also indicate "now" when they stop feeling the vibration.

The Timed Up and Go (TUG) test is designed to measure dynamic balance based on the time it takes for patients to stand up and walk, providing quantitative results. The patient starts the test by sitting on a standardized chair (46 cm high). During the test, the patient is instructed to stand up from the chair, walk 3 meters away, turn around, and then return to sit back down on the chair. The duration of this process is measured. Lower values indicate better stability. A cutoff value of 13.5 seconds has been used to identify high fall risk in the TUG test.

Manual Muscle Test: Muscle strength is evaluated using the MRC (Medical Research Council) muscle strength scale.

Reflexes:Patellar reflex: The reflex hammer is struck on the patella, and extension of the leg is observed. Achilles reflex: With one hand, the patient's foot is lightly dorsiflexed, and the Achilles tendon is struck; plantar flexion is observed in the ankle.

The Douleur Neuropathique 4 (DN4) pain scale score will be used to screen for diabetic peripheral neuropathic pain. The DN4 scale consists of 10 questions, 7 of which inquire about symptoms, and 3 that assess the patient's clinical examination for neuropathy. The symptoms assessed include a burning sensation, pain from cold, electric shock sensations, tingling, pins and needles, numbness, and itching. The sensory exams assess touch hypoesthesia, pin-prick hypoesthesia, and brush allodynia. Each "yes" response to a question receives 1 point. To calculate the total score, points obtained from the symptom inquiry and clinical examination are added together. The maximum total score is 10, and a score of 4 or higher is considered indicative of neuropathic pain

The numeric pain scale will be used to assess the intensity of neuropathic pain. The patient is asked to provide a value between 0 and 10 to indicate the intensity of their pain. Higher scores are associated with an increase in pain severity.

The Toronto Clinical Neuropathy Score (TCNS) will be used to assess the severity of Diabetic Peripheral Polyneuropathy (DPPN). The Turkish version of the Toronto clinical scoring system is a reliable and valid tool for assessing polyneuropathy in Turkish-speaking patients. The TCNS is preferred in clinical studies because of its ease of use, patient acceptability, ability to classify the severity of DPPN, and its representation of clinical changes related to the progression of DPPN. The scale consists of three sections: symptom scores, sensory test scores, and reflex scores.The first section includes scoring symptoms in the upper and lower extremities .The second section includes scoring the bilateral Achilles and patellar reflexes. The third section involves scoring the sensation in the toe. The total score ranges from a minimum of 0 (no neuropathy) to a maximum of 19 points.

Six-Minute Walk Test (6MWT) is a commonly used test to assess functional capacity. The test area should be a corridor with a minimum length of 30 meters, flat, and firm surface. The corridor should be marked every 3 meters. Turnaround points are indicated with objects such as orange traffic cones. A line is drawn for the start and end of the test. Recommended materials for the test include a stopwatch, a device to count laps, cones to mark turning points, a chair placed within easy reach, oxygen support (to be given if necessary), and a blood pressure cuff. The patient should wear comfortable clothing and shoes suitable for walking. They can use any walking aids such as crutches or a walker. Medications or treatments should be taken as usual. The patient should have had a light meal before the test and should not have engaged in heavy physical activity within the 2 hours preceding the test. There should be no warm-up period before the test.

The SF-12 Quality of Life Scale will be calculated using an online calculator tool, providing two types of scores: physical and mental scores.

The IPAQ scale was developed to address the general health problem of insufficient physical activity, which necessitates large population studies and allows for cross-country comparisons. Validity studies conducted across multiple countries have proven that this questionnaire is valid and reliable. This survey assesses individuals based on the types of physical activities they perform in their daily lives. The questions asked pertain to the time spent physically active over the past 7 days.

Vibration sense will be assessed using a traditional 128 Hz tuning fork. When the stem of a 128 Hz tuning fork is placed on the dorsal aspect of the interphalangeal joint of the hallux, a healthy person can feel the vibration as long as it continues (15-20 seconds). In conditions leading to peripheral nerve damage (such as polyneuropathy), vibration sense is impaired. The examiner holds the proximal end of the tuning fork with one hand, while the distal end is struck strongly against the palm of the examiner's other hand. The examiner should try to strike the tuning fork with consistent force for each assessment. After striking, the tuning fork is placed just proximal to the nail bed, on the dorsal aspect of the distal phalanx of the hallux.Before applying the tuning fork, the participant is instructed to verbally respond with "yes" if they can initially feel the vibration, and they should also indicate "now" when they stop feeling the vibration.

The Timed Up and Go (TUG) test is designed to measure dynamic balance based on the time it takes for patients to stand up and walk, providing quantitative results. The patient starts the test by sitting on a standardized chair (46 cm high). During the test, the patient is instructed to stand up from the chair, walk 3 meters away, turn around, and then return to sit back down on the chair. The duration of this process is measured. Lower values indicate better stability. A cutoff value of 13.5 seconds has been used to identify high fall risk in the TUG test.

Manual Muscle Test: Muscle strength is evaluated using the MRC (Medical Research Council) muscle strength scale. Reflexes:Patellar reflex: The reflex hammer is struck on the patella, and extension of the leg is observed. Achilles reflex: With one hand, the patient's foot is lightly dorsiflexed, and the Achilles tendon is struck; plantar flexion is observed in the ankle.