Genetic Testing for Diabetes

As DNA testing becomes available to the general public, people are often faced with a decision about undergoing testing for disease risk. Science has established a clear link between genetics and diabetes. If you have a family history of diabetes, an understanding of the relationship between DNA damage and diabetes will help you decide if DNA testing is right for you.

DNA Diabetes

There are two main forms of diabetes. Type 1 diabetes causes the immune system to destroy insulin releasing cells. Eventually the body does not produce any insulin and can not absorb the glucose it needs to make energy. Five to 10 percent of all diabetics have Type 1 diabetes, which usually starts in childhood. Type 2 diabetes most often appears in adulthood, and is characterized by the body being unable to properly respond to insulin.

Type 1 diabetes is believed to be mostly genetically inherited.

• There are many different genes associated with Type 1 diabetes risk.
• The most influential Type 1 diabetes genes are the insulin gene, and genes located in the HLA region.
• People who have an insulin gene with two specific repeating patterns in their DNA are two to five times more likely to develop diabetes.
• Diabetes DNA mutations that occur in at least two genes of the HLA region are responsible for 40 to 50 percent of inherited disease risk. Depending on which allele, (or version) of these genes you inherit, you are more or less likely to develop diabetes. The DR3 and DR4 alleles are found in almost 95 percent of individuals with Type 1 diabetes.

Type 2 diabetes risk is determined by both environmental and genetic factors:

• Lack of exercise, obesity and poor diet can significantly increase a person's risk for Type 2 diabetes.
• Research suggests that people with two copies of an allele which controls insulin secretion are twice as likely to develop Type 2 diabetes as those in the general public.

Understanding DNA Testing for Diabetes

DNA testing for diabetes risks has both benefits and limitations. A high risk for diabetes does not determine when or if a person is going to develop the disease. Someone who receives a low-risk result can not guarantee that he or she will not develop diabetes. Research is still ongoing and scientists have not yet identified all of the genetic mutations associated with diabetes risk.

A new test is now available for the public to test Type 2 diabetes risks. This type of testing can help motivate people to make important lifestyle changes. Those who would like to reduce the risk of Type 2 diabetes, or possibly delay its onset should consider:

• a regular exercise program
• healthy diet low in sugary sweets
• maintaining a healthy weight.

There are no preventative measures for Type 1 diabetes; however a healthy lifestyle can be helpful in the successful management of this disease.

Diabetes DNA tests may also be useful in scientific research. The American Diabetes Associations recommends genetic testing for diabetes in children who have a parent or sibling with Type 1 diabetes, and wish to participate in a research study. Doctors can also use the test in those with impaired glucose tolerance to help determine the most effective treatments.

Resources

Adams, Amy. (2000). Genes Can Cause Type 1 Diabetes. Retrieved September 15, 2008, from the GeneticHealth.com Web site: http://www.genetichealth.com/dbts_genetics_of_type_1_diabetes.shtml.

Grady, Denise (2006). Genetic Testing for Diabetes May Gauge Risk, but Is the Risk Worth Knowing? Retrieved September 15, 2008, from the NYTimes.com Web site: http://www.nytimes.com/2006/08/08/health/08diab.html?_r=2