Type 2 Diabetes

In T2D, the body does not respond well to insulin, a hormone that helps transfer sugar out of the blood and into the body's cells and tissues, where it is used for energy. At first, the islet cells in the pancreas try to produce more insulin in an effort to make the body respond. But eventually, these cells cannot keep up and stop working altogether, so sugar stays in the blood. People with T2D have difficulty maintaining normal blood sugar levels. If blood sugar levels are not controlled, T2D can lead to the development of several life-threatening complications such as heart disease, stroke, hypertension, and kidney failure. Patients with T2D also develop blood circulation problems that can lead to blindness and even amputation of extremities in extreme cases.

It is estimated that a total of 20.8 million people, or 7% of the US population, were living with diabetes in 2005. Of those, an estimated 6 million were undiagnosed. Currently, over 1.5 million people are diagnosed with diabetes in the US each year, and the number of new cases of T2D is steadily increasing due to the growing number of older Americans, increasing obesity, and lack of exercise.

An increasing number of genetic variants have been consistently found to contribute to the risk of developing T2D. Variants in the TCF7L2 gene appear to be associated with the highest risk of developing T2D, and also can predict the likelihood that a person will convert from a state of pre-diabetes (borderline blood sugar levels) to full-blown T2D. Several studies have shown that overweight pre-diabetics who have certain TCF7L2 variants have a 55-70% chance to develop T2D within 3 to 5 years after their initial diagnosis. It has been shown by the NIH-sponsored Diabetes Prevention Program Outcome study that weight loss and treatment with metformin can prevent or delay the transition from pre-diabetes to T2D in this high-risk group.

In the past few years numerous discoveries have been made in the genetics of T2D and recently more variants associating with risk of developing T2D were published by deCODE genetics scientists in consortia with several other groups. To date twenty-one genes, including the TCF7L2 gene, have been discovered located on twelve chromosomes; 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12 and 17.

The deCODEme Genetic Scan identifies the variants referred to above and uses them to provide customers of European descent with a personalized interpretation of their genetic risk for developing T2D. For East Asians and African Americans, the deCODEme Genetic Scan currently provides a personalized genetic risk interpretation using nine and two variants, respectively, on which scientific risk data are available.

At present, the necessary scientific information to interpret the genetic risk for customers of other ethnicities is not available. This information will be added as soon as it becomes available and we are assured of its quality.

This content was last reviewed on February 11, 2010.