People with diabetes may develop nerve damage due to high blood sugar. This condition is known as diabetic neuropathy. This condition can be classified into four types: peripheral, autonomic neuropathy, proximal neuropathy (diabetic polyradiculopathy), or mononeuropathy (focal neuropathy), depending on the nerves it affects. Although these conditions develop slowly, they may not be diagnosed or show symptoms until much later. Knowing their signs can help diagnose them and begin treatment earlier.

• Peripheral neuropathy: This is the most common form of neuropathy that affects the legs and feet first. Over time, the symptoms may spread to the arms. Some symptoms include numbness or reduced ability to feel pain or temperature changes in the feet and toes, a tingling or burning sensation, a sharp pain that worsens at night, extreme sensitivity to touch, muscle weakness, loss of reflex response, foot problems such as ulcers, infections, and deformities, and bone and joint damage.
• Autonomic neuropathy: The autonomic nervous system controls several different bodily functions, including blood pressure, heart rate, sweat glands, eyes, bladder, digestive system, and sex organs. Diabetes and excessive blood sugar could lead to nerve damage in any of these systems, giving rise to symptoms such as hypoglycemia unawareness, urinary incontinence or urinary retention, constipation or uncontrolled diarrhea, slow stomach emptying or gastroparesis, which could lead to nausea, vomiting, sensation of fullness, and loss of appetite, difficulty swallowing, erectile dysfunction, vaginal dryness in women, increased or decreased sweating, drops in blood pressure when rising from sitting or lying down (orthostatic hypotension), problems regulating body temperature, increased heart rate even when at rest, and changes in the way the eyes adjust from light to dark and distance to the nearness.
• Proximal neuropathy: This condition affects the thighs, hips, buttocks, or legs and is common among those with type-2 diabetes. Most people feel the symptoms on one side of the body, but they may also spread to the other. Some symptoms include severe pain in the buttock, hip, or thigh, weak or shrinking thigh muscles, difficulty rising from a seated position, and chest or stomach pain.
• Mononeuropathy: This involves damage to one nerve located anywhere in the body. It occurs suddenly and generally does not cause long-term complications. Some symptoms of this condition include double vision or difficulty focusing the eyes, paralysis on one side of the face, pain in the shin or the foot, pain in the front of the thigh, and weakness that may cause difficulty lifting the front part of the foot.

This condition may also arise when a nerve is compressed, for instance, in carpal tunnel syndrome. Symptoms of this may include numbness or tingling in the fingers or hands and a loss of strength that may cause one to drop things.

The American Diabetes Association (ADA) recommends beginning annual screening for diabetic neuropathy with the diagnosis of type-2 diabetes and five years after the diagnosis of type-1 diabetes. Following the advised treatment can help reduce the impact of excessive sugar on the body. This can help prevent the development of conditions such as diabetic neuropathy and ensure a better quality of life.