Type 2 diabetes in children may develop gradually. About 40 percent of children who have type 2 diabetes have no signs or symptoms and are diagnosed during routine physical exams.

Other children might experience:

• Increased thirst and frequent urination. Excess sugar building up in your child's bloodstream pulls fluid from tissues. As a result your child might be thirsty — and drink and urinate more than usual.
• Weight loss. Without the energy that sugar supplies, muscle tissues and fat stores simply shrink. However, weight loss is less common in children with type 2 diabetes than in children with type 1 diabetes.
• Fatigue. Lack of sugar in your child's cells might make him or her tired and lethargic.
• Blurred vision. If your child's blood sugar is too high, fluid may be pulled from the lenses of your child's eyes. Your child might be unable to focus clearly.
• Slow-healing sores or frequent infections. Type 2 diabetes affects your child's ability to heal and resist infections.

The exact cause of type 2 diabetes is unknown. But family history and genetics appear to play an important role. Inactivity and excess fat — especially abdominal fat — also seem to be important factors.

What is clear is that people with type 2 diabetes don't process glucose properly anymore. As a result, sugar accumulates in the bloodstream instead of doing its normal job of fueling the cells that make up muscles and other tissues.

Most of the glucose in people's bodies comes from the food they eat. When food is digested, sugar enters the bloodstream. Moving sugar from the bloodstream to the body's cells requires a hormone (insulin).

Insulin comes from the pancreas, a gland located behind the stomach. The pancreas secretes insulin into the bloodstream after a person eats.

As insulin circulates, it allows sugar to enter the cells — and lowers the amount of sugar in the bloodstream. As the blood sugar level drops, so does the secretion of insulin from the pancreas.

Type 2 diabetes develops when the body becomes resistant to insulin or when the pancreas stops making enough insulin. The resulting buildup of sugar in the bloodstream can cause life-threatening complications.

Researchers don't fully understand why some children develop type 2 diabetes and others don't, even if they have similar risk factors. However, it's clear that certain factors increase the risk, including:

• Weight. Being overweight is a primary risk factor for type 2 diabetes. The more fatty tissue children have — especially inside and between the muscle and skin around the abdomen — the more resistant their bodies' cells become to insulin. The association between obesity and type 2 diabetes is even stronger in youth than in adults.
• Inactivity. The less active your child is, the greater his or her risk of type 2 diabetes. Physical activity helps your child control his or her weight, uses glucose as energy, and makes your child's cells more responsive to insulin.
• Family history. Children's risk of type 2 diabetes increases if they have a parent or sibling with the disease.
• Race. Although it's unclear why, people of certain races — including African-Americans, Hispanics, Native Americans, Asian-Americans and Pacific Islanders — are more likely to develop type 2 diabetes.
• Age and sex. Many children develop type 2 diabetes at the start of puberty. Adolescent girls are likelier to develop type 2 diabetes than are adolescent boys.
• Birth weight and gestational diabetes. Low birth weight and being born to a mother who had gestational diabetes during the pregnancy are both associated with a higher risk of developing type 2 diabetes.

Type 2 diabetes can affect nearly every major organ in your child's body, including the blood vessels, nerves, eyes and kidneys. The long-term complications of type 2 diabetes develop gradually. But eventually, diabetes complications may be disabling or even life-threatening.

Complications of type 2 diabetes include:

• High blood pressure
• High cholesterol
• Heart and blood vessel disease
• Stroke
• Nonalcoholic fatty liver disease
• Kidney disease
• Blindness
• Amputation
• Certain skin conditions

Keeping your child's blood sugar level close to normal most of the time can dramatically reduce the risk of these complications.