What Are Complications of Diabetes?

Diabetes is a disease that interferes with how your body uses blood sugar (glucose). Type 1 diabetes (T1D) occurs when your pancreas doesn’t make enough insulin to help your cells use glucose for energy. Type 2 diabetes (T2D) develops over time due to diet and lifestyle choices, resulting in your cells becoming resistant to insulin.1

Both types of diabetes result in uncontrolled high blood sugar levels, which can be damaging to your body. Over time, health complications can develop as a result of this damage. Examples of complications include eye problems, nerve damage, and kidney problems. Learning about the different complications of diabetes can help you learn to identify symptoms and get the treatment you need.2

Maintaining healthy blood sugar levels is an important part of your overall health. When blood sugar levels are consistently high for an extended period of time, they can begin to damage certain parts of the body. Eventually, you may be diagnosed with other health conditions. The risk of long-term complications of diabetes can also increase if you have other underlying health problems, such as high blood pressure or cholesterol levels.2

Eye Problems from Diabetes

High blood sugar levels from diabetes can damage the eyes over time, leading to a number of complications. If left untreated, some of these eye conditions may eventually lead to vision loss or blindness. It’s important to go to your regular eye exams so that your eye doctor can make an early diagnosis and get you the treatment you need.

Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common cause of blindness in working-age adults in the United States. This condition is caused by damage to the blood vessels in the retina, which is the light-sensitive tissue in the back of the eye that helps send images to the brain. There are two stages of DR — nonproliferative DR (NPDR) and proliferative DR (PDR).

NPDR is the early stage of the disease in which the blood vessels in the retina become damaged and begin to leak blood. They may also begin to swell, which can block blood flow to the retina. Without proper oxygen and nutrients, the retina eventually becomes damaged. This can lead to blurry vision or floating dark spots in your vision (floaters).

PDR is the advanced stage of the disease in which new blood vessels begin to grow from the retina. This can also cause scarring. Blood may also leak into the clear gel filling of the eye, known as the vitreous. PDR leads to severe vision loss and is a medical emergency that needs immediate medical treatment.3

DR can be treated with laser beams, anti-vascular endothelial growth factor (anti-VEGF) therapies and surgery.

Glaucoma Related to Diabetes

Glaucoma refers to a group of eye diseases caused by increased pressure in the eye, which eventually damages the optic nerve. This nerve connects to the back of the retina to help send images to the brain. Often, people don’t notice any glaucoma symptoms because vision loss develops slowly over time. With this, it’s important to go to your regular eye checkups so your doctor can monitor for any new problems.3

The most common type of glaucoma is open-angle glaucoma. In this type, fluid from your eye is still able to leave through a drainage angle between the iris (colored part of your eye) and the cornea (outer layer of your eye). However, other parts of the drainage system are damaged, which causes a buildup of fluid. Over time, this increases pressure in the eye, leading to more damage. People with diabetes are twice as likely to develop open-angle glaucoma compared to those without.4

People with diabetic retinopathy may also develop neovascular glaucoma if new, abnormal blood vessels grow into the iris. These blood vessels block fluid from draining out of the eye, which can also raise pressure.5

Glaucoma can be treated with medicated eye drops and surgeries that help drain extra fluid from the eyes.4

Cataracts from Diabetes

Cataracts cause the clear lens covering your eye to become cloudy, which can cause blurry or double vision. Your eyes may also be more sensitive to light, and you may have difficulty seeing in the dark. While cataracts are common in older individuals, they tend to occur more often in younger people who have diabetes. This is because high blood sugar levels can cause changes in your eye lens that increase your risk of developing cataracts.

Your risk of developing cataracts increases if you have a buildup of fluid in the macula (area near the center of the retina), known as macular edema, or if you’ve had diabetes for a long period of time. Eye surgeries, injuries, and injections can also increase your risk of cataracts. The best way to treat them is cataract surgery, which removes the cloudy lens from your eye and replaces it with an artificial one.6

Kidney Problems from Diabetes

The kidneys are filled with millions of nephrons, or tiny blood vessels and tubules that exchange blood. High blood sugar levels can damage these blood vessels, making it harder for them to properly filter waste and excess fluid from your blood. As a result, you may develop diabetic nephropathy or chronic kidney disease (CKD). People with diabetes who also have high blood pressure may also have kidney damage, as increased pressure can damage the delicate tissues in the kidneys.7

Diabetic nephropathy refers to general kidney damage caused by diabetes. Symptoms of diabetic nephropathy include:8

  • Needing to urinate frequently
  • Swelling of the hands, feet, ankles, or eyes
  • Uncontrollable blood pressure
  • Shortness of breath
  • Nausea or vomiting
  • Fatigue
  • Loss of appetite

If left untreated, diabetic nephropathy can develop into CKD. This disease affects around one-third of people with T1D and T2D.7 CKD develops slowly over time, so you may not notice any symptoms until it has progressed and you need treatment. Your doctor will monitor your kidney function with blood and urine tests to make sure they’re working properly.

Diabetic nephropathy and CKD can be managed with medications to help treat other associated complications, including those that treat high blood pressure, swelling, and high cholesterol levels. If you develop end-stage CKD and your kidneys can no longer filter waste and fluid on their own, you’ll need dialysis. This treatment removes your blood and filters out the extra fluid and waste from it. In some cases, a kidney transplant can be done to replace the diseased kidney with a healthy one from a donor.9

Nerve Damage from Diabetes

Diabetes can also cause nerve damage, known as diabetic neuropathy. Over time, high blood sugar levels can damage different nerves around the body, leading to a variety of symptoms depending on what nerves are affected. There are four main types of diabetic neuropathy — peripheral, autonomic, proximal, and focal.10

Peripheral Neuropathy

Peripheral neuropathy is a common type of neuropathy that affects nearly 50 percent of people with diabetes. It mainly affects the nerves in the legs and feet, but it can also affect the hands and arms. You may notice a burning, numbness, or tingling “pins and needles” sensation in your feet or hands. These symptoms may affect your ability to balance yourself while walking. You may also have swollen feet, which can become worse at night.

Your doctor may prescribe you different medications to help with pain, including skin creams or sprays, antidepressants, or seizure medications (anticonvulsants). Unfortunately, there is no way to reverse nerve damage, so your doctor will work with you to find the best way to manage your pain and other symptoms.11

Autonomic Neuropathy

Autonomic neuropathy involves damage to the nerves that regulate your internal organs. These include your:

  • Bladder
  • Digestive system
  • Heart rate and blood pressure
  • Sex organs
  • Sweat glands

You may notice any number of symptoms depending on what organs are affected. These include:

  • Trouble urinating or bladder infections
  • Diarrhea, constipation, nausea, vomiting, and trouble swallowing
  • Changes in heart rate or blood pressure that may make you feel dizzy, or chest pain
  • Sexual dysfunction or difficulty having an orgasm
  • Sweating excessively at night or while eating, inability to control body temperature

Depending on your symptoms, your doctor may recommend certain medications to help address your health problems. Managing your diabetes can also help alleviate some of these symptoms.12

Focal Neuropathy

Focal neuropathy affects only a single nerve, typically found in your leg, torso, hand, or head. This neuropathy is less common than peripheral or autonomic neuropathies. The most common type of focal neuropathy is entrapment, in which a nerve becomes trapped or compressed between tissues and bones. Around one-quarter of people with diabetes have nerve compression in the wrist, and around 10 percent of those cases are carpal tunnel syndrome.

Another less common focal neuropathy is cranial neuropathy, which impacts the nerves in the head. This can lead to problems controlling the muscles in your face, or eye problems.

Most people who don’t have entrapment recover on their own in a few weeks or months without treatment. For neuropathies with entrapment, your doctor may recommend medications for pain and inflammation, and wearing a brace or splint to take pressure off the nerve. In some cases, surgery may be necessary.13

Proximal Neuropathy

Proximal neuropathy is a rare neuropathy that affects the nerves in your thigh, hip, or buttock. It’s more common in men than women, and it tends to occur in people ages 50 and older. The majority of people with proximal neuropathy have T2D. Symptoms of proximal neuropathy include:

  • Leg weakness that makes standing difficult
  • Sudden and severe pain in your thigh, hip, or buttock
  • Loss of muscle tissue (wasting)
  • Weight loss
  • Loss of reflexes, such as when your doctor taps your knee

Your doctor may recommend medications used to treat pain in peripheral neuropathy, along with physical therapy to help strengthen the muscles in your legs. Many people recover from the condition within a few years, some without treatment.14

Heart Disease and Stroke Risk with Diabetes

People with diabetes are twice as likely to develop heart disease or have a stroke than someone without diabetes. The longer you’ve had diabetes, the more likely you are to have these complications. Many people with diabetes have high levels of LDL (“bad”) cholesterol and low levels of HDL (“good”) cholesterol. They may also have high blood pressure (hypertension), which puts extra stress on the heart and blood vessels. Together, these factors raise your risk for heart disease.15

Heart disease refers to several different conditions that affect the heart and blood vessels. The most common is coronary artery disease, in which plaques (deposits) of cholesterol build up in the blood vessels that bring blood to the heart. If your heart doesn’t receive enough blood, you may have a heart attack. If a blood clot caused by plaque buildup enters your brain, you may have a stroke. Many people with diabetes also develop peripheral arterial disease (PAD), in which the arteries in your legs and feet become hardened with plaque deposits.

Your doctor will likely prescribe you medications to help control your blood pressure, cholesterol, and blood sugar levels. You can also make lifestyle changes such as diet modifications and exercise to help you get your blood sugar and cholesterol levels under control. If you’re overweight, losing weight can also help lower these levels. If you smoke, quitting can help cut your risk of heart disease in half.2

New Treatments for Diabetes Complications

The best way to prevent diabetes complications is to follow the treatment plan your doctor gives you. For those with Type 1 diabetes, monitoring your blood sugar levels and using insulin as needed can help keep your levels in check. Type 2 diabetes can be treated with a combination of insulin and other diabetes medications, along with a proper diet and exercise. Together, these treatments can help you prevent further health complications and lead a healthier life.

As doctors and researchers continue to learn more about different diabetes complications, they will develop new treatments and diagnostic tools to catch the conditions early. There are currently several diabetes complications clinical trials investigating these therapies.