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.

Diabetes Mellitus


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.

Symptoms

Diabetes initially might not cause any symptoms. It can sometimes be caught early with a routine blood test before a person develops symptoms.

When diabetes does cause symptoms, they may include:

  • excessive urination
  • excessive thirst, leading to drinking a lot of fluid
  • weight loss.

People with diabetes also have an increased susceptibility to infections, especially yeast (Candida) infections.

When the amount of insulin in the blood stream is too low, extremely high blood sugar levels can lead to dangerous complications. The body can become too acidic, a condition called diabetic ketoacidosis. Or the blood sugar level gets so high, the person becomes severely dehydrated. It’s called hyperosmolar syndrome.

The symptoms of these complications include confused thinking, weakness, nausea, vomiting, and even seizures and coma. In some cases, diabetic ketoacidosis or hyperosmolar syndrome is the first sign that a person has diabetes.

The treatment of diabetes also can produce symptoms. Too much glucose-lowering medicine, relative to dietary intake, can lead to a blood sugar level that has dropped too low (called hypoglycemia). Symptoms of hypoglycemia include:

  • sweating
  • trembling
  • dizziness
  • hunger
  • confusion
  • seizures and loss of consciousness (if hypoglycemia is not recognized and corrected).

You can correct hypoglycemia by eating or drinking something that has carbohydrates. This raises your blood sugar level.

Long-term diabetes can have other complications, including:

  • Atherosclerosis — Atherosclerosis is fat buildup in the artery walls. This can impair blood flow to all parts of the body. The heart, brain, and legs are affected most often.
  • Retinopathy — Tiny blood vessels in the retina (the part of the eye that sees light) can become damaged by high blood sugar. The damage can block blood flow to the retina, or can lead to bleeding into the retina. Both reduce the retina's ability to see light. Caught early, retinopathy damage can be minimized by tightly controlling blood sugar and using laser therapy. Untreated retinopathy can lead to blindness.
  • Neuropathy — This is another term for nerve damage. The most common type is peripheral neuropathy, which affects nerves in the feet and hands. The nerves to the legs are damaged first, causing pain and numbness in the feet. This can advance to cause symptoms in the legs and hands. Damage to the nerves that control digestion, sexual function, and urination can also occur.
  • Foot problems — Any sores, injuries, or blisters on the feet can lead to the following complications:
    • If peripheral neuropathy causes numbness, a person may not feel any irritation or injury that occurs on the foot. The skin can break down and form an ulcer, and the ulcer can get infected.
    • Blood circulation can be poor, leading to slow healing of any foot injuries. Left untreated, a simple sore can become very large and get infected. If medical treatment cannot heal the sore, an amputation may be required.
  • Nephropathy — This refers to damage to the kidneys. This complication is more likely if blood sugars remain elevated and high blood pressure is not treated aggressively.