### Instruction:  Disease name:

    Diabetes mellitus overview

: What is it?

Diabetes mellitus is a condition defined by persistently high levels of sugar (glucose) in the blood. There are several types of diabetes. The two most common are called type 1 diabetes and type 2 diabetes. During digestion, food is broken down into its basic components. Carbohydrates are broken down into simple sugars, primarily glucose. Glucose is a critically important source of energy for the body's cells. To provide energy to the cells, glucose needs to leave the bloodstream and get inside the cells. An organ in the abdomen called the pancreas produces a hormone called insulin, which is essential to helping glucose get into the body's cells. In a person without diabetes, the pancreas produces more insulin whenever blood levels of glucose rise (for example, after a meal), and the insulin signals the body's cells to take in the glucose. In diabetes, either the pancreas's ability to produce insulin or the cells' response to insulin is altered. Type 1 diabetes is an autoimmune disease. This means it begins when the body's immune system mistakenly attacks other cells in the body. In type 1 diabetes, the immune system destroys the insulin-producing cells (called beta cells) in the pancreas. This leaves the person with little or no insulin in his or her body. Without insulin, glucose accumulates in the bloodstream rather than entering the cells. As a result, the body cannot use this glucose for energy. In addition, the high levels of blood glucose cause excessive urination and dehydration, and damage the body's tissues. Type 2 diabetes occurs when your body's cells become less responsive to insulin's efforts to drive glucose into the cells, a condition called insulin resistance. As a result, glucose starts to build up in the blood. In people with insulin resistance, the pancreas "sees" the blood glucose level rising. The pancreas responds by making extra insulin to try to usher the glucose into the cells. At first, this works, but over time, the body's insulin resistance gets worse. In response, the pancreas makes more and more insulin. Finally, the pancreas gets "exhausted." It cannot keep up with the demand for more and more insulin. As a result, blood glucose levels rise and stay high. Type 2 diabetes is also called adult-onset diabetes. That's because it almost always used to start in middle or late adulthood. However, more and more children and teens are now developing this condition. Type 2 diabetes is much more common than type 1 diabetes. It tends to run in families. Obesity also increases your risk of type 2 diabetes. It is truly a different disease than type 1 diabetes, although both types involve a high blood glucose level and the risk of complications associated with it. Another kind of diabetes, called gestational diabetes, happens in women who have higher-than-expected blood sugar levels during pregnancy. Once it occurs, it lasts throughout the remainder of the pregnancy. Like the other types of diabetes, gestational diabetes happens when the hormone insulin can't efficiently move sugar (glucose) into the body's cells so it can be used as fuel. In gestational diabetes, the body does not respond well to insulin, unless insulin can be produced or provided in larger amounts. In most women, the disorder goes away when the pregnancy ends, but women who have had gestational diabetes are at increased risk of developing type 2 diabetes later.