What Is Diabetes, Exactly?

This informational guide, part of PS's Condition Center, lays out the realities of this health concern: what it is, what it can look like, and strategies that medical experts say are proven to help. You should always consult your doctor regarding matters pertaining to your health and before starting any course of medical treatment.

Diabetes is a chronic condition that occurs when your body loses its ability to keep the level of sugar in your blood under control. Out of the 37.3 million adults in the US who have diabetes, 90 to 95 percent of them have type 2 diabetes. But one in five people with diabetes don't know they have the condition at all — a problem, since in the long term, untreated diabetes can have dire consequences, including kidney failure, lower-limb amputations, and blindness.

Ahead, we talked to an MD and rounded everything you need to know about diabetes, including what causes it, types of diabetes, signs and symptoms, and how diabetes is treated.

Nuha El-Sayed, MD, is the vice president of Health Care Improvement at the American Diabetes Association.

"Diabetes is a disease that occurs when your blood glucose, also called blood sugar, is too high," according to the National Institute of Diabetes and Digestive and Kidney Disease (NIDDK). But how does that happen exactly? Well, after you eat, your body breaks down most of the food into glucose, or sugar, and releases it into your bloodstream, causing your blood sugar to rise. When the system is functioning normally, the rise in blood sugar triggers your pancreas to release insulin, a hormone that moves the glucose out of your blood and into your body's cells, where it's used for energy.

There are three main types of diabetes that impact this function: type 1, type 2, and gestational diabetes. "When people develop type 2 diabetes, their bodies' insulin doesn't function well, which allows too much sugar to stay in the blood," says Nuha El Sayed, MD, vice president of Health Care Improvement at the American Diabetes Association. As blood-sugar levels increase, cells in the pancreas continue to release more insulin.

Symptoms of type 2 diabetes include increased thirst and hunger, blurred vision, frequent urination, headache, fatigue, weight loss, and vaginal and skin infections. But symptoms can also be mild — one reason so many people remain undiagnosed.

With type 1 diabetes, the body attacks cells in the pancreas, resulting in a complete absence of insulin and sugar buildup in the bloodstream, per the Mayo Clinic. Type 1 diabetes tends to appear during childhood, but it can also develop in adults. Type 1 diabetes symptoms are similar to type 2 symptoms including increased thirst and hunger, blurred vision, frequent urination, headache, fatigue, weight loss, and bed-wetting.

Gestational diabetes is specifically diagnosed during pregnancy and, like other forms of diabetes, is characterized by the body's inability to process sugar. Experts suspect it's caused by changes in hormone levels that occur during pregnancy. Most people who develop it won't notice any symptoms, although it can cause thirstiness and increased urination. But in the US, most pregnant people get screened for it by their ob-gyn because gestational diabetes can result in complications for them (high blood pressure and preeclampsia, C-section delivery, and future diabetes) and their little one (low birth weight, preterm birth, and breathing difficulties, among other things).

Type 1 and gestational diabetes are caused by different factors. For type 1 diabetes, the body's immune system turns on itself, damaging and destroying the cells in the pancreas that produce insulin, per the Mayo Clinic. Your genes and environmental factors tend to play a role in your risk. Gestational diabetes, on the other hand, is thought to be triggered by pre-pregnancy weight gain and hormone changes.

Type 2 diabetes occurs when the body experiences cell resistance (in muscle, fat, and liver) to insulin and the pancreas struggles to make enough insulin to regulate blood sugar. Several factors may be responsible for the development of these issues, per the Mayo Clinic.

There are several tests doctors can use to diagnose diabetes. The NIDDK lists the following as the most common:

Lifestyle changes, like managing your weight, staying physically active, and establishing healthy eating patterns, are critical for diabetes care, Dr. El Sayed says. In fact, this advice applies to all three common forms of diabetes: type 1, type 2, and gestational. "There are also a number of medications that can help people control their glucose and reduce their risk of complications," she adds.

Insulin pumps, which deliver insulin through a thin tube under the skin, and continuous blood-sugar monitoring, which uses a small sensor under the skin to track blood sugar, have simplified diabetes care and improved the overall outlook of those with the condition.

Although you can't technically be cured of type 2 diabetes, it's possible to go into remission and improve to the point where you can go off medication, Dr. El Sayed says. The same cannot be said for people with type 1 diabetes. Complete remission is very rare, although partial remission or a "honeymoon phase" may be possible. Gestational diabetes, on the other hand, tends to go away after delivery.

Ginny Graves is an award-winning writer in the San Francisco Bay Area whose work focuses on science, psychology, health, nature, and the human-animal bond.