10 Unexpected Side Effects and Complications of Diabetes, According to Doctors

When you have type 2 diabetes, your body can’t properly use insulin, a hormone that regulates blood sugar. In turn, your HDL (or “good”) cholesterol lowers, and your levels of harmful blood fats called triglycerides rise. Insulin resistance also contributes to hardened, narrow arteries, which in turn increases your blood pressure.

As a result, about 2 of 3 people with diabetes also have hypertension—a risk factor for stroke, heart disease, and trouble with thinking and memory. Failing to control high blood pressure and high cholesterol, either with diet and exercise alone or by adding medications, accelerates the rate at which all your other complications progress, says Robert Gabbay, M.D., Ph.D., chief medical officer at Joslin Diabetes Center in Boston.

“It appears that people with diabetes have some abnormalities of blood flow control to the brain,” explains Helena Rodbard, M.D., an endocrinologist based in Maryland. “And this appears to be correlated with a more rapid loss of mental function with age,” she says, including the ability to plan, organize, remember things, prioritize, pay attention, and get started on tasks.

To protect your brain health, you’ll want to stay active physically and mentally, logging at least 30 minutes of exercise a day and keeping your mind stimulated. “Read, socialize, work, and play games that challenge your intellect,” Dr. Rodbard says. “Keep a positive, optimistic attitude—don’t permit yourself to become depressed.”

People with diabetes are more likely to develop periodontal disease, an infection of the gum and bone that can lead to painful chewing problems and tooth loss. “This is due in part to elevated blood sugar that modifies the collagen in all of our tissues,” Dr. Rodbard says. “It’s also due to a slight increase in susceptibility to infections of all kinds.”

On the other hand, gum disease—specifically inflammation of the gums or development of deep abscesses—can raise blood sugar and make diabetes harder to control, according to Dr. Hamdy. To prevent periodontitis, brush and floss daily and consider using a mild antiseptic mouthwash to knock out any lingering plaque.

Many men with diabetes will experience some level of erectile dysfunction (ED) in their lifetime. “ED can be psychological or due to reduced testosterone,” Dr. Hamdy says, noting that low testosterone is common among people with diabetes, especially if they’re obese. “However, in patients with a long duration of diabetes, changes in blood vessels and nerve supply to the penis could be the cause.” If you have diabetes, are over age 40, and have been having trouble with your male equipment, see your doctor.

Middle-aged and older women with diabetes also tend to have sexual issues, according to a study of nearly 2,300 women published in Obstetrics & Gynecology, likely because nerve damage can impair lubrication and the ability to achieve orgasm.

While we all lose some hearing as we age, hearing loss is twice as common in people with diabetes compared to those without the condition, according to the CDC. Diabetes may lead to hearing loss by damaging the small blood vessels and nerves in the inner ear, the CDC says.

The best way to protect your hearing is to keep your blood sugar levels in check, Dr. Rodbard says. In fact, in a study from Henry Ford Hospital in Detroit, older women with uncontrolled diabetes had more hearing loss than women the same age who had well-controlled diabetes. The CDC also suggests getting your hearing checked every year and avoiding other causes of hearing loss, like exposure to loud noises, when possible.

Having diabetes spikes your risk for all kinds of skin issues, including bacterial infections such as boils and urinary tract infections, fungal infections, and itching. “Fungal infections, especially yeast infections, are so common that they may even be the first sign of diabetes in someone who hasn’t yet been diagnosed,” Dr. Hamdy says.

In some cases, skin infections can be tied to obesity, because there are “moist places between skin folds that may breed bacteria and fungi, including candida,” Dr. Rodbard says.

Unfortunately, several diabetes medications increase the risk of fungal infections of the genitalia, Dr. Hamdy says, because they enhance glucose excretion in urine, fueling growth of bacteria and fungus. Controlling blood sugar levels helps with prevention, but once you have an infection, seek out the usual treatments: over-the-counter antifungal vaginal creams and suppositories, to be used as directed.

This potentially serious sleep disorder, in which the throat muscles intermittently relax and block the airway during sleep, affects around 50% of people with diabetes, Dr. Hamdy says, especially those who are obese and have a collar size of more than 17 for men and 16 for women.

The most obvious sign of obstructive sleep apnea (OSA) is audible snoring. Unfortunately, like gum disease, “sleep apnea may worsen diabetes control,” Dr. Hamdy says, possibly because the two conditions share risk factors. Treatment for OSA may involve using a device to keep your airway open at night or wearing a mouthpiece that thrusts your jaw forward. In severe cases, surgery can help by altering the structure of the nose, mouth, or throat.

Roughly 1 in 3 people with diabetes older than age 40 have diabetic retinopathy, or damage to the light-sensitive tissue at the back of the eye. This happens because elevated blood glucose levels over time harm the eye’s delicate blood vessels, a process that can begin as early as 7 years before diagnosis.

The good news is, treating these problems early can reduce risk of blindness by 95%, per the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Over time, high blood glucose thickens and scars the nephrons, tiny structures within the kidneys that filter your blood. About 7% of the time, you’ll already have protein leaking into your urine—an early sign of kidney problems—by the time you receive a type 2 diabetes diagnosis.

About half of those who don’t take steps to control their diabetes will sustain kidney damage within 10 years, and 40% of those will progress to kidney failure, a condition requiring either dialysis or a kidney transplant, says Betul Hatipoglu, M.D., an endocrinologist at the Cleveland Clinic.

About half of people with type 2 diabetes will develop neuropathy, the most common diabetes complication. At first, you might have no symptoms or feel a mild tingling or numbness in your hands or feet, says Dr. Gabbay. But eventually, this form of nerve damage can cause pain, weakness, and digestive troubles as it strikes the nerves that control your gastrointestinal tract.

In addition to managing your blood sugar, being physically active, eating a healthy diet, and keeping up with recommended medications can help prevent diabetes-related nerve damage, the NIDDK says.