According to the U.S. Centers for Disease Control and Prevention, diabetes is the leading cause of kidney failure, new blindness, and leg and foot amputations unrelated to injury. It's a major cause of heart disease, stroke, and nerve damage. Poor blood sugar control may also raise the risk for Alzheimer's disease.
If you have type 2 diabetes, your body doesn't use insulin properly to convert glucose into energy. As a result, blood sugar levels become elevated. This buildup of glucose, known as hyperglycemia, can damage blood vessels and vital organs. The A1C blood test is commonly used to see how well, on average, a patient's blood sugar level has been managed over the past two to three months.
"A person's A1C level is an excellent marker of complications," said Joel Zonszein, MD, director of the Clinical Diabetes Center at Montefiore Medical Center in New York City. "If you have a lower number, you'll be healthier." The American Diabetes Association recommends an A1C of 7 percent, or an average glucose level of 145 milligrams per decileter (mg/dL).
The following are three common types of complications that can occur when diabetes isn't properly controlled over time.
Eye Damage (Retinopathy)
Diabetic retinopathy is the leading cause of new-onset blindness in adults. It occurs when blood vessels of the retina swell and leak fluid into the macula, where focusing occurs. The result, known as macula edema, causes blurred vision. A more serious form of eye complication, called proliferative retinopathy, occurs when new blood vessels form in the retina to replace damaged ones. Scar tissue can develop and cause the retina to become detached.
Fortunately, "this kind of damage doesn't happen overnight," said Stephanie Marioneaux, an ophthalmologist in Chesapeake, Va., and a clinical spokesperson for the American Academy of Ophthalmology. Vision loss can be prevented if the blood vessel damage is caught early enough through regular eye exams.
"If we're seeing damage in the retina that means their blood sugar has been elevated for a while," said Dr. Marioneaux.
Nerve Damage (Neuropathy)
When hyperglycemia damages blood vessels that feed oxygen and nutrients to the nerves, it can result in nerve damage or neuropathy. Common signs include tingling, pain, or numbness in the feet and hands.
Patients may develop blisters or sores on their feet that can spread infection to the bone and cause tissue death. These infections are very hard to treat and can result in amputation.
"If people are experiencing the numbness and tingling, they should be checking their feet regularly for any sores or wounds and get them seen by a doctor before they get infected," said Priscilla Hollander, MD, an endocrinologist at the Baylor Endocrine Center in Dallas.
While A1C is "a great tool," Betul Hatipoglu, MD, an endocrinologist at the Cleveland Clinic, said it's not a replacement for daily blood sugar monitoring. "Keeping it level can decrease chances of terrible complications that could potentially cause you to lose your limbs," said Dr. Hatipoglu.
Kidney Disease (Nephropathy)
Diabetes is the leading cause of chronic kidney disease in the United States. "About 10 percent of people with type 2 diabetes will develop [it]," said Dr. Hollander.
High blood sugar levels compromise the kidneys' ability to properly filter waste products in the blood. Protein that's useful to the body leaks into the urine, while wastes start to collect in the blood. Left untreated, this can lead to kidney, or renal, failure requiring a machine to filter the blood (known as dialysis) or a kidney transplant.
According to Hollander, it usually takes about 10 years for diabetic kidney disease to manifest, and it can be caught in the early stages. A simple urine test can detect excess protein in the urine. Other signs to look for include frequent urination, weight gain, and ankle swelling.
"The incidence is improving," said Hollander. "And we've made a lot of progress by controlling blood pressure, which plays a big role in furthering kidney damage."
For anyone with type 2 diabetes, as Dr. Zonszein points out, "the sooner you can catch that your blood glucose hasn't been under control, the better you can prevent these complications."
