A number of disorders are grouped under the umbrella of diabetes, usually identified by type. Each type is distinct in terms of what causes it, how it's treated, and the complications that can arise.

Here's a quick look at each type of diabetes: definitions, some fast facts, and how common each type is in the U.S. and worldwide.

Prediabetes and Insulin Resistance

Prediabetes is a condition that can lead to type 2 diabetes. In order to understand what causes it, you have to understand how the body handles sugar (or glucose) and processes it into energy.

Glucose enters the body primarily through the food and beverages you consume. The pancreas makes a hormone called insulin in order to help the glucose in your blood enter your muscles, fat, and liver to be used as energy. When the body does not use the insulin effectively, your pancreas initially produces more insulin to overcome this resistance. But when your pancreas is not able to keep up with the demand, the result is hyperglycemia, when blood glucose is too high. (6)

Insulin resistance is the primary cause of prediabetes, but the causes of insulin resistance aren’t fully understood. Family history, advancing age, excess weight, and a sedentary lifestyle are among the known risk factors. (7)

There are multiple tests to determine whether you have prediabetes. One way to measure the amount of glucose in the blood is through a hemoglobin A1C test, which shows how much glucose attaches to the hemoglobin in your red blood cells, on average, over the past three months. A normal A1C level is below 5.7 percent. If your A1C is between 5.7 and 6.4 percent, you have prediabetes. At 6.5 percent or above, you have diabetes. (8)

In 2015 there were 84 million adults with prediabetes in the U.S., nearly one in three people in the nation. It’s an age-related condition, experienced by nearly half of all adults older than 65. (4,6) A person with prediabetes has up to a 50 percent chance of developing diabetes within 5 to 10 years if it goes untreated or undertreated.

But it’s possible to get your blood glucose level back within normal range with lifestyle modifications such as eating a healthier diet; eating smaller, more frequent meals to keep your blood sugar stable; and exercising more, says Patricia Happel, DO, an assistant professor and associate medical director at the New York Institute of Technology College of Osteopathic Medicine in Old Westbury, New York. In fact, losing just 7 percent of your body weight (or 15 pounds if you weigh more than 200 pounds) may help lower your risk of developing type 2 diabetes by 58 percent. (9)



Learn More About Insulin Resistance



Learn More About Prediabetes

Type 2 Diabetes

As mentioned, type 2 diabetes is caused by insulin resistance. (10) Between 90 percent and 95 percent of all diabetes cases are type 2, and nearly one in four people who have it don’t know they do. (4)

The condition typically develops in people who are older than 45 and is more common in the U.S. among people who are Asian, black, and Hispanic. It’s also strongly correlated with carrying excess weight. Up to 9 out of 10 people worldwide who have type 2 diabetes are overweight or obese. (11) But the majority of people who are overweight do not develop type 2 diabetes. By their mid- to late 70s, about 2 in 10 overweight adults and 4 in 10 obese adults in the U.S. have been diagnosed with diabetes. (12)

You can treat type 2 diabetes through diet and lifestyle changes to lower your blood glucose levels and weight. In addition, many people with the condition monitor their blood glucose levels regularly; take oral medications; and sometimes inject themselves with insulin through a pen, pump, or needle. (13)

If untreated or inadequately managed, type 2 diabetes may lead to numerous health complications, some of them life-threatening. They include periods of hypoglycemia (low blood sugar); diabetic neuropathy (nerve damage) that results in pain or numbness; foot and limb injuries, diabetic ulcers, deformities or even amputations; kidney disorders; heart disease; blindness; skin problems; digestive disorders; sexual dysfunction; problems with teeth and gums; and problems regulating blood pressure. (14)

Learn More About Type 2 Diabetes