The Centers for Disease Control and Prevention estimates that 151,000 people below the age of 20 have diabetes. In children, type 1 diabetes is the most common form of diabetes, but the incidence of type 2 diabetes has increased in children and adolescents. Type 1 diabetes is an autoimmune disease in which the immune system destroys insulin-producing cells. In type 2 diabetes, liver, fat and muscle cells are resistant to insulin, so more insulin is required to maintain the appropriate balance of blood sugar levels.
Type 1 Diabetes
The CDC reports that each year 13,000 children are diagnosed with type 1 diabetes in the United States. The incidence of type 1 diabetes increase two- to three-fold between 1960 and 2010 in the United States and as much as 10-fold in some European countries. Many environmental factors have been proposed to increase the risk of developing the disease, although no single environmental factor has of yet been proven to be causative of the disease. What is clear is that the progression of type 1 diabetes requires the combination of an environmental trigger, which likely has seasonal variation and a genetic predisposition for the disease.
Environmental Factors
The environmental factors that have been proposed to increase the risk for type 1 diabetes are exposure to certain viruses, vitamin A and D deficiencies and nitrites. Some viruses, such as the Epstein-Barr virus, Coxsackie virus, mumps virus and cytomegalovirus, have been shown to trigger the autoimmune destruction of the insulin-producing cells, but the research studies are conflicting. Recently Dr. Matthias von Herrath, a prominent researcher in the field, concluded that some viral infections actually delay the progression of type 1 diabetes. Exposures to cow's milk at a young age and foods containing gluten have also been implicated as triggers for type 1 diabetes. Interestingly, the "hygiene hypothesis" has gained considerable favor in explaining the etiology of type 1 diabetes. This hypothesis proposes that autoimmune diseases in general are associated with the fact that children are less exposed to microorganisms and pathogens, especially in developed countries, which negatively impacts their immune systems.
Genetics
The CDC reports the incidence of type 1 diabetes is about 1 in 500 in the general population. If an immediate family member has the disease, the risk increases to one in 20. Some gene regions have been linked to type 1 diabetes in familial studies, but the rapid rise in the disease cannot be explained by familial inheritance. Over 10 different genes have been identified as potential contributors to the development of type 1 diabetes and the ones with known functions are involved in mediating immune responses. Type 1 diabetes is more prevalent in Caucasians than in other racial groups, which could either be related to specific genetic differences or environmental determinants.
Other Factors
Children who have a high birth weight or who are born to mothers with gestational diabetes have an increased risk for developing type 1 diabetes. A study in the May issue of "Diabetologia" reported the risk of type 1 diabetes was increased by 20 percent in children born by Caesarean section delivery.
Type 2 Diabetes
Type 2 diabetes accounts for between and 8 and 46 percent of all new cases of diabetes reported at pediatric centers, according to the CDC. Type 2 diabetes is also a complex disease in which both environmental and genetic factors play a role. A review in the journal, "Australian Family Physician" reports that children with parents who have type 2 diabetes have an 80 percent chance of developing the disease in their lifetime. Families share diet and exercise habits in addition to genes, and in approximately 70 percent of type 2 diabetics the development of the disease is more dependent on environmental and behavioral factors. Only two genes that increase the susceptibility to type 2 diabetes have been identified, and they encode for proteins that influence the function of insulin-secreting cells or the function of cells targeted by insulin.
Obesity
As in adulthood, the risk of developing type 2 diabetes in childhood is highly correlated to obesity. The 2003-2004 National Health and Nutrition Examination Survey reports that nearly 14 percent of children between the ages of 2 and 5, and 19 percent of children between the ages of 6 and 11 are overweight. This is almost a two-fold increase over the last 20 years. Abdominal fat is especially noted as a specific risk factor for type 2 diabetes in children. Insulin resistance, which is a decrease in cellular sensitivity to insulin, is common in overweight children and is a condition that may progress to type 2 diabetes. Physical inactivity and poor diets in children are risk factors for both obesity and type 2 diabetes. Girls are more prone than boys to develop type 2 diabetes because of their higher body fat content.
Other Factors
Children with type 2 diabetes are most often diagnosed during puberty, as hormones during pubertal growth influence insulin action and blood glucose levels. The review in the journal, "Australian Family Physician" notes that children have an increased risk for developing type 2 diabetes if their mothers had gestational diabetes and also if the pregnancy resulted in prenatal undernutrition. The American Diabetes Association reports that American Indians, Mexican Americans and African Americans have a higher risk for developing type 2 diabetes than Caucasians.
References
- Centers for Disease Control and Prevention: Children and Diabetes
- Australian Family Physician: Children get Type 2 Diabetes Too
- Journal of Pediatric Psychology: Influences on Child Eating and Weight Development from a Behavioral Genetics Perspective
- American Diabetes Association: Genetics of Diabetes
- Diabetes: Can We Learn From Viruses How to Prevent Type 1 Diabetes
