Diabetes can damage peripheral nerves because blood sugar that stays high over time harms the nerves themselves and the tiny blood vessels that carry them oxygen and nutrients. Blood fats, including triglycerides, may add to this damage. The feet and legs are often affected first, causing symptoms such as tingling, burning pain, numbness, or weakness. Managing diabetes can help lower the risk or slow further damage.
How does diabetes damage peripheral nerves?
Peripheral nerves connect the brain and spinal cord to the rest of the body. They carry messages that help a person feel touch, pain, and temperature and control muscle movement. They also help the body respond to changes in the surrounding environment. When these nerves become damaged, the messages may not travel normally, leading to changes in sensation, movement, or both.
According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), high blood glucose and elevated blood fats, including triglycerides, can damage nerves over time. High blood glucose can also injure the small blood vessels that supply nerves with oxygen and nutrients. When these blood vessels are damaged, the nerves may not receive the support they need to function properly.
What happens to nerves when blood sugar stays high?
Blood glucose provides energy for the body's cells, but prolonged exposure to higher-than-expected glucose levels can harm nerve tissue. Diabetes-related nerve damage is not explained by a single blood sugar reading. It develops in the context of longer-term metabolic changes, and the level or length of exposure associated with nerve injury differs from person to person.
Damage can affect the way sensory nerves carry information. Signals may become weaker or fail to reach the brain normally, which can reduce the ability to feel pain or temperature. In other cases, damaged nerves may send abnormal signals that cause burning, tingling, or shooting pain. Nerves involved in muscle control may also be affected, sometimes contributing to weakness or changes in balance.
The precise course of nerve damage is not identical in everyone with diabetes. Some people develop noticeable symptoms, while others have changes in nerve function before they recognize anything unusual. Diabetes-related peripheral neuropathy can occur in people with either type 1 or type 2 diabetes.
Why are the feet and legs often affected first?
Diabetes-related peripheral neuropathy most often affects the feet and lower legs first. The hands and arms can become affected as well. Symptoms may develop gradually, and the pattern can differ among individuals. Some people notice discomfort or unusual sensations, while others mainly experience reduced feeling.
The Centers for Disease Control and Prevention (CDC) explains that nerve damage often begins in the feet and may cause tingling, pain, numbness, or weakness. Loss of sensation is particularly important because it can make injuries harder to notice. A person may not feel a blister, a cut from footwear, or an injury caused by walking barefoot.
When a foot injury goes unnoticed, continued pressure or friction can make the problem worse. Diabetes can also make wounds harder to heal, increasing the risk of infection. This is why protecting the feet is important even when there is little or no pain.
What increases the risk of diabetes-related nerve damage?
Having diabetes does not mean that a person will inevitably develop peripheral neuropathy. However, some factors are associated with a greater likelihood of nerve damage. The Mayo Clinic identifies prolonged diabetes, poor blood sugar control, kidney disease, high blood pressure, high cholesterol, excess body weight, and smoking as factors that can increase risk. Alcohol-related harm and individual genetic factors may also contribute.
- Blood glucose frequently above the person's target: Longer-term exposure to higher glucose levels can increase the risk of nerve injury.
- Longer duration of diabetes: The likelihood of developing neuropathy tends to increase the longer a person has diabetes.
- High blood pressure or high cholesterol: These conditions can add to problems affecting blood vessels and overall nerve health.
- Kidney disease: Kidney problems can occur alongside diabetes and are associated with a higher risk of nerve complications.
- Smoking and excessive alcohol use: Both can contribute to health problems that affect nerves and circulation.
- Other individual factors: Body weight, age, and genetic influences may also affect susceptibility.
These factors do not predict an individual's outcome with certainty. They help healthcare professionals understand which aspects of a person's health and diabetes management may need attention.
What symptoms can result from peripheral nerve damage?
When peripheral nerves are affected, a person may notice changes in sensation, muscle function, or balance. These experiences are examples of possible effects rather than a way to determine the cause of a symptom. Some people experience pain, while others have reduced sensation with little discomfort.
- Tingling or pins and needles: An unusual prickling feeling in the feet, legs, hands, or arms.
- Burning or shooting pain: Discomfort that may feel sharp, electric, or painful even with light touch.
- Numbness: Reduced ability to feel touch, pain, or changes in temperature.
- Increased sensitivity: Ordinary contact, such as fabric touching the skin, may feel uncomfortable or painful.
- Weakness or balance changes: Nerve damage may affect muscle control or awareness of where the feet are positioned.
These symptoms can have causes other than diabetes, so their presence alone does not establish the cause. Persistent or worsening symptoms, weakness that affects everyday activities, changes in walking, or pain that disrupts sleep should be discussed with a healthcare professional. A foot wound that appears infected or does not heal needs prompt medical assessment.
Can diabetes-related nerve damage be prevented or slowed?
Good diabetes management can reduce the risk of developing nerve complications and help limit further damage. The Cleveland Clinic emphasizes managing blood glucose and addressing other health factors, including high blood pressure and high cholesterol. The appropriate targets depend on a person's circumstances and should be agreed upon with their healthcare professional.
Measures that support nerve health include taking prescribed diabetes medicines as directed, following an eating and physical activity plan suited to individual needs, avoiding smoking, and discussing alcohol use with a healthcare professional. Managing related health conditions is also important. These steps can reduce risk, but they cannot guarantee that neuropathy will never develop.
People living with diabetes should inspect their feet every day for cuts, blisters, redness, swelling, or other changes, especially if sensation is reduced. Shoes that fit properly can help protect the skin from repeated pressure. Regular clinical foot examinations allow healthcare professionals to check sensation, circulation, and signs of injury. A clinician may recommend more frequent checks when foot problems or reduced sensation are present.
Could another condition be causing the nerve symptoms?
Not every nerve problem in a person with diabetes is necessarily caused by diabetes itself. Other health conditions, nutritional deficiencies, medicines, or pressure on a nerve can also cause peripheral neuropathy. For example, vitamin B12 deficiency and certain thyroid or kidney problems may need to be considered during an evaluation.
The NIDDK's guidance on peripheral neuropathy explains that healthcare professionals may review a person's medical history, examine the feet and nervous system, and order tests to investigate other possible causes. Metformin, a medicine commonly used for type 2 diabetes, is among the factors associated with low vitamin B12 levels in some people. This does not mean everyone taking metformin will develop a deficiency; testing can help determine whether one is present.
When symptoms develop, healthcare professionals consider how they began, which parts of the body are affected, how they have changed, and whether other medical conditions or medicines could be involved. Identifying contributing factors helps guide appropriate care rather than assuming that diabetes explains every symptom.
What is the main takeaway about diabetes and peripheral nerves?
Diabetes damages peripheral nerves mainly through the effects of prolonged high blood glucose and abnormal blood fats, which can injure nerve tissue and the small blood vessels that nourish it. The feet and legs are commonly affected first, and the resulting loss of sensation can allow injuries to go unnoticed. Consistent diabetes management, attention to related health conditions, regular foot examinations, and prompt attention to new or worsening symptoms can help reduce the impact of nerve damage.