Nerve damage, known as diabetic neuropathy, is the most common complication of diabetes. It affects up to 50% of people with the disease, making it more prevalent than eye, kidney, or heart complications. The damage typically starts in the feet and toes, progressing slowly over years, and is considered the most costly and disabling complication of diabetes overall.
How High Blood Sugar Damages Nerves
Prolonged high blood sugar triggers a chain of destructive processes inside nerve tissue. Excess glucose generates harmful molecules called reactive oxygen species, which damage DNA and trigger inflammation throughout the nervous system. At the same time, sugar molecules attach directly to nerve proteins in a process called glycation, gradually building up in every component of peripheral nerve tissue: the protective coating around nerve fibers, the nerve fibers themselves, and the tiny blood vessels that supply them with oxygen.
This accumulation stiffens and distorts nerve structures over time. High glucose also activates several metabolic pathways that wouldn’t normally be very active, further compounding the damage. The result is nerves that transmit signals poorly, transmit pain signals when they shouldn’t, or stop transmitting altogether.
What Nerve Damage Feels Like
The most common form, distal symmetric polyneuropathy, starts in the toes and feet and works its way upward. Early symptoms include numbness, burning, and prickling or tingling sensations. Some people experience pain from stimuli that shouldn’t be painful, like the touch of a bedsheet against their feet. These symptoms can be persistent or come and go.
About one in three people with diabetic neuropathy develop the painful form. A 2025 meta-analysis in Frontiers in Neurology estimated painful diabetic neuropathy at 33.9% prevalence among those with nerve damage. The remaining patients may feel numbness or nothing at all, which carries its own risks. When you can’t feel your feet, small cuts, blisters, and pressure sores go unnoticed and untreated.
From Nerve Damage to Foot Ulcers
Loss of sensation in the feet is the primary driver behind diabetic foot ulcers, one of the most serious downstream consequences of neuropathy. Roughly 2 million Americans develop a diabetic foot ulcer each year. The statistics from that point are sobering: within five years of developing an ulcer, over 50% of patients die from related complications, and 5% lose a limb. Foot ulcers aren’t just a wound problem. They signal advanced vascular disease and nerve damage that affect the entire body.
Checking your feet daily for cuts, redness, swelling, or warm spots is one of the simplest protective habits if you have diabetes. Properly fitted shoes, regular foot exams, and prompt treatment of any wound, no matter how minor, can prevent the cascade from neuropathy to ulceration to amputation.
Other Major Complications by Frequency
While neuropathy tops the list, diabetes damages multiple organ systems simultaneously. Here’s how other common complications compare.
Eye Damage (Retinopathy)
Diabetic retinopathy affected an estimated 9.6 million Americans in 2021, according to the CDC. Among people with diabetes, prevalence ranges from about 13% in those under 25 to 28.4% in the 65 to 79 age group. Of the 9.6 million affected, 1.84 million had vision-threatening forms, including severe damage to the blood vessels in the retina or swelling in the central part of the eye responsible for sharp vision. Men are affected at higher rates than women, and Black Americans have the highest prevalence among racial groups. Regular dilated eye exams can catch retinopathy before vision loss occurs, since early stages typically produce no symptoms.
Kidney Disease (Nephropathy)
Between 30% and 40% of people with diabetes develop kidney disease. Diabetes is responsible for 30% to 50% of all new cases of end-stage kidney disease in the United States, making it the single leading cause of kidney failure. The damage happens gradually as high blood sugar injures the tiny filtering units inside the kidneys. Early kidney disease produces no symptoms and is only detectable through blood and urine tests, which is why routine screening matters. By the time symptoms like swelling, fatigue, or changes in urination appear, significant damage has already occurred.
Cardiovascular Disease
Heart disease and stroke are the leading causes of death among people with diabetes. Adults with diabetes are roughly twice as likely to have a heart attack or stroke compared to those without the condition. High blood sugar damages blood vessel walls throughout the body, accelerating the buildup of fatty deposits that narrow arteries. This process runs parallel to the nerve and kidney damage, sharing many of the same underlying mechanisms: inflammation, oxidative stress, and glycation of tissues.
Why These Complications Overlap
It’s common for people with diabetes to develop several complications at once rather than just one. The underlying cause is the same: chronically elevated blood sugar damaging blood vessels and nerves throughout the body. Small blood vessel damage drives neuropathy, retinopathy, and nephropathy. Large blood vessel damage drives heart attacks and strokes. Someone with neuropathy in their feet likely has some degree of damage happening in their eyes, kidneys, and arteries at the same time.
The timeline matters. Most complications develop gradually over years or decades of poorly controlled blood sugar. Keeping blood sugar levels within target ranges is the single most effective way to slow or prevent all of these complications. Even modest improvements in blood sugar control reduce the risk of nerve damage, eye disease, and kidney disease significantly. The earlier control is achieved, the greater the protection, but improvements at any stage still offer measurable benefit.