Diabetes and Genetics – By the Numbers
Scientists and physicians now know that there are different types of diabetes, with a variety of causes. Some, but not all, forms of diabetes are related to genetic irregularities. Thanks to research at the University of Chicago Medical Center and other centers around the world, we now know that there are a multitude of genetic factors that can directly cause diabetes or raise a person’s risk of developing the disease.
These numbers and facts help put diabetes into perspective:
- An estimated 30 million people in the U.S. have diabetes, and the numbers continue to grow. In large part, growing prevalence of diabetes (Type 2) is related to the growing percentage of Americans who are overweight or obese.
- Type 2 diabetes is much more common than Type 1 diabetes. Experts estimate that 90-95 percent of people with diabetes Type 2, which often can be controlled through diet, weight control and oral medications.
- Type 1 diabetes is an autoimmune disorder. The body’s own immune system destroys cells in the pancreas (beta cells) that normally are responsible for making insulin. Without the ability to make insulin, people with Type 1 diabetes must take supplementary insulin throughout the day (either by shots or pump) in order to control their blood glucose (blood sugar) level.
- Most people with Type 1 diabetes are diagnosed during childhood, that’s why Type 1 was previously called “juvenile diabetes”, but in fact it can occur at any age beyond 6 months of life.
- About one-tenth of 1 percent (.1%, or 1 in 1,000) of all people with Type 1 diabetes are diagnosed as infants, usually before they’re 6 months old. This is called “neonatal diabetes.”
- About half of this 0.1% of people with neonatal diabetes has a mutation in one of two critical proteins involved in insulin secretion (the Kir6.2 mutations in the KCNJ11 gene, and SUR1 mutations in the ABCC8 gene). Another very small group has a mutation in the insulin protein. In the U.S., that may be as many as 2,000 people who have mutations in the genes for these three proteins, but so far fewer than 50 are known. Based on research led by Professor Andrew Hattersley of Peninsula Medical School in the U.K., physicians at the University of Chicago Medical Center have successfully treated several children with mutations in Kir6.2 with pills enabling them to abandon insulin pumps and injections. Other genes causing early onset diabetes are discussed at HTTP://WWW.DIABETESGENES.ORG/, including the insulin gene itself.
- Transient neonatal diabetes is another form where infants present with severe diabetes with keotacidosis, but then go on to no longer need insulin. Some of these patients will have diabetes later on in life, from adolescence to young adulthood. The causes of this syndrome include abnormalities of chromosome 6, as well as certain mutations in KCNJ11 and ABCC8. Some of these would be treatable.
- Most forms of diabetes are “polygenic” – i.e. related to several genes. However, perhaps 1-5 % of cases may be familial due to mutation in a single gene (“monogenic”).