Diabetes is a group of diseases characterized by high levels of blood glucose resulting from defects in insulin production, insulin action, or both. Insulin is a cellular protein that regulates glucose levels in the blood.
Type 1 diabetes is often called “juvenile diabetes” because it generally appears during childhood or adolescence. It develops when the body’s immune system mistakenly destroys the insulin-producing islet cells of the pancreas, a small gland behind the stomach. As a result, the body is unable to properly utilize energy in food or control sugar levels in the blood stream.
Type 1 diabetics must endure many painful insulin injections each day in order to live and function normally and, at present, there is no cure. However, recent research indicates that a cure may be possible through transplants of pancreatic islet cells.
Type 2 diabetes usually begins as insulin resistance, a disorder in which the cells do not use insulin properly. As the need for insulin rises, the pancreas gradually loses the ability to produce it. This type of diabetes usually occurs later in life, affecting 90% of patients diagnosed with diabetes.
Type 2 diabetes is associated with older age, obesity, family history of diabetes, physical inactivity and race/ethnicity. African Americans, Hispanic/Latino Americans, Native Americans, and some Asian Americans, Native Hawaiian or other Pacific Islanders are at particularly high risk for Type 2 diabetes. Type 2 diabetes is also increasingly being diagnosed in children and adolescents. Current treatment includes using diabetes medicines, making wise food choices, exercising regularly, taking aspirin daily, and controlling blood pressure and cholesterol.
Diabetes can lead to many serious long-term health problems and early death. It can cause blindness, kidney failure and severe problems involving the gums and teeth. It can also cause nerve damage and blood flow problems that result in impaired sensation or pain in the feet or hands and amputation of limbs. One of the most serious problems caused by diabetes is heart disease. People who have diabetes are more than twice as likely to develop heart disease or a stroke as people without diabetes.
Human and Social Costs
Over 18 million people in the U.S., or 6.3% of the population, have diabetes. Over one million new cases are diagnosed every year. Diabetes was the sixth leading cause of death listed on U.S. death certificates in 2000. The American Diabetes Association estimates that diabetes contributes to over 200,000 deaths annually nationwide. However, total deaths caused by diabetes are probably under-reported because it ultimately causes other health problems that may be listed as the cause of death.
In 2000, a total of 129,183 people with diabetes underwent dialysis or kidney transplantation. About 60% to 70% of people with diabetes have mild to severe forms of nervous system damage. The results of such damage include slowed digestion of food in the stomach, carpal tunnel syndrome and other nerve problems.
It’s estimated that diabetes costs Americans a total of $132 billion annually, including $92 billion in direct medical costs and $40 billion in costs related to disability, work loss and premature death. Diabetes accounts for one of every four Medicare dollars spent in the U.S.
The Kaiser Family Foundation estimates that 6% of adults between the ages of 18 and over 75 in our state have diabetes. The majority of adults diagnosed with diabetes are between the ages of 45 and 64 (43%) and age 65 and older (42%). Most of these older patients have Type 2 diabetes.
The Potential for Stem Cell Cures
More than 50 years of research on adult stem cells, taken from adult tissues, has produced such lifesaving treatments as bone marrow transplants for leukaemia patients. And, adult stem cells are likely to provide additional cures for some diseases in the years ahead.
However, the new frontier in stem cell research involves early, or “embryonic,” stem cells (ES cells). Unlike adult stem cells, ES cells have the potential to turn into and regenerate any type of cell or tissue in the human body. As a result, ES cells could provide cures for many currently incurable or common diseases and injuries that cannot be cured with adult stem cells, or more effective treatments than adult stem cells may provide.
There are two basic sources of ES cells for such potential therapies. One source is the leftover embryos at fertility clinics that would otherwise be discarded and destroyed. ES cells can also be produced with Somatic Cell Nuclear Transfer (SCNT), a process that uses a patient’s own cells and an unfertilized human egg to make ES cells. SCNT has the added advantage of producing ES cells that will automatically match the patient’s genetic makeup. As a result, SCNT avoids the need to find a genetically matching donor and the problem of immune system rejection, two limitations associated with donated adult and ES cells.
Indications that ES cells could benefit diabetes patients have been provided by a number of recent studies. For example, researchers at Stanford University have successfully turned mouse ES cells into insulin-making tissue that kept diabetic mice alive.
Other research has shown that insulin-producing islet cells can be transplanted into patients with Type 1 diabetes and that such transplants could potentially provide a cure. However, the only current source of replacement islet cells is from human cadavers and not enough donated islet cells are available from this source to treat the many children and adults who have Type 1 diabetes. In addition, because donated islet cells are not a perfect genetic match with the patient’s DNA, patients who receive donated islet cells must take powerful drugs to prevent rejection. These drugs have severe and potentially fatal side effects and rejection often occurs despite the medication.
SCNT could help overcome these limitations and revolutionize the treatment of juvenile diabetes by providing a way to make virtually unlimited supplies of transplantable islet cells that match a patient’s DNA.
In the future, transplants of ES cells could also help people who suffer from Type 2 diabetes. For example, ES cells could be used to help repair tissues and organs that are damaged by effects of Type 2 diabetes and alleviate some of the health problems associated with this disease.
SCNT could also play an important role in developing future “gene therapy” treatments for inherited diseases like Type 1 diabetes, which develop because the patient has an abnormal or malfunctioning gene. If the gene that causes a disease can be identified, scientists could take a patient’s somatic cell, such as a skin cell, and replace the defective gene with a normal gene inserted using recombinant DNA techniques. The “corrected” cell could then be used in the SCNT procedure to generate stem cells with normally functioning genes. These could then be directed to develop into islet cells and put back into the patient’s body, potentially providing a cure. This technique would overcome some of the most difficult hurdles facing gene therapy today.
In addition, SCNT has given medical researchers a method of growing cells that have the defects associated with a disease in a laboratory setting. This use of SCNT provides new ways to study how a disease like diabetes progresses at the cellular level and to test the effectiveness of new drugs or other treatments that may cure or slow the progress of the disease.
The consensus of the medical and patient community is that all types of stem cell research should be pursued in the effort to find cures for diseases like diabetes, and that ES cells can play an important role in this effort.
That’s why ES cell research is strongly supported by the overwhelming majority of medical researchers; medical organizations like the American Medical Association; and disease and patient advocacy groups like the American Diabetes Association, Juvenile Diabetes Research Foundation and Diabetes Research Institute Foundation.