Type 2 diabetes is a disease of metabolism. Under normal circumstances, the food people eat is converted into glucose (blood sugar) during digestion. Glucose is carried in the bloodstream and moved into the cells through the action of a hormone called insulin. Insulin acts as a key to open the cells to glucose. Without insulin the body cannot access the glucose. Cells require the glucose for energy.

In type 1 diabetes, an autoimmune disease in which the body mistakenly attacks the pancreas, people produce little or no insulin. In type 2 diabetes, the body either produces insufficient amounts or has trouble using insulin. In either case, the glucose builds up in the bloodstream until it is excreted in the urine.

Type 2 diabetes is by far the most common form of diabetes. The U.S. National Institutes of Health (NIH) estimated in 2006 that 20.8 million Americans – 7 percent of the population – had diabetes in 2005, 6.2 million of them undiagnosed. Of the diabetic population, an estimated 90 to 95 percent (18.7 million to 19.8 million people) had type 2 diabetes.

Only 5.8 million Americans were diagnosed with diabetes in 1980, and the total in 1996 was still below 9 million, according to the U.S. Centers for Disease Control and Prevention (CDC). The soaring incidence of type 2 diabetes in recent years is blamed largely on the soaring incidence of obesity, due to physical inactivity and overeating.

There are several reasons why people develop type 2 diabetes:

• Muscle and fat cells become resistant to insulin. Obesity contributes to this insulin resistance.
  
  
• Pancreatic beta cells do not release enough insulin to meet the body’s needs.
  
  
• The liver releases too much glucose into the bloodstream.

Type 2 diabetes usually appears in middle-aged and older adults but is increasingly being diagnosed in children and adolescents. Once diagnosed, patients will have to take action to prevent the following glucose problems associated with type 2 diabetes:

• Hyperglycemia. Abnormally high glucose. Left untreated, it can lead to coma or death.
  
  
• Hypoglycemia. Abnormally low glucose. Left untreated, it can lead to convulsions, unconsciousness or brain damage.
  
  
• Hyperosmolar hyperglycemic nonketotic syndrome (HHNS). A dangerous condition involving severe hyperglycemia and dehydration. Left untreated, HHNS can lead to seizures, coma or death.

Type 2 diabetes significantly increases a person’s risk of developing many serious complications, including:

• Heart conditions and stroke. Cardiovascular disease is the No. 1 killer of people with type 2 diabetes.

• Eye diseases (diabetic retinopathy, glaucoma, cataracts, macular degeneration) and blindness.
  

• The kidney disease diabetic nephropathy and chronic kidney failure.
  
  
• The nerve disease diabetic neuropathy, including gastroparesis.
  
  
• Foot problems and leg amputations.
  
  
• Skin disorders.
  
  
• Decreased cognitive abilities and dementia.
  
  
• Sexual dysfunction.
  
  
• Pregnancy complications.
  
  
• Some types of cancer.
  
  
• Urinary incontinence.
  
  
• Yeast infections, urinary tract infections, gingivitis, thrush, tuberculosis and other infections.

In addition, recent research has found an increased prevalence of asthma and Parkinson’s disease in people with type 2 diabetes.

Type 2 diabetes was once known as noninsulin-dependent diabetes mellitus (NIDDM) or adult-onset diabetes. However, those terms are not accurate because some people with type 2 diabetes need to take insulin, and increasing numbers of children are being diagnosed with the disease. Federal health statistics revealed in 2005 that about 2 million U.S. adolescents have prediabetes, a condition that often leads to type 2 diabetes.

Diabetes is the sixth-leading cause of death in the United States and contributes to hundreds of thousands of other deaths a year but is often underreported in mortality statistics, according to the NIH. The overall U.S. death rate fell 32 percent from 1970 to 2002, but the death rate from diabetes rose 45 percent, according to an analysis by the American Cancer Society in 2005.

Type 2 diabetes is growing throughout the world, especially where prosperity and the adoption of Western lifestyles are increasing, such as India and China. The International Diabetes Federation estimates that 230 million people have diabetes and projects this figure to reach 350 million by 2025. It warns that, if trends continue, type 2 diabetes may within 25 years become the largest epidemic the world has ever experienced. Using revised methodology, the World Health Organization estimated in 2005 that 2.9 million people globally died of diabetes in 2000, about three times its previous estimate.

Recent large-scale studies found that two-thirds of Americans and half of Canadians with type 2 diabetes had poor control of their glucose. However, the CDC reported in 2005 that U.S. hospitalizations for diabetic complications decreased 35 percent from 1994 to 2002.