Can you picture a future where diabetes can essentially be cured with a one-time injection? This reality may not be as far off as you might think. In fact, it looks like some dogs with type one diabetes have already been cured of their disease.
First some background information:
Most dogs have what is called type one diabetes, as opposed to type two diabetes (the opposite is true for cats). With type one diabetes, the pancreas stops manufacturing sufficient amounts of insulin, usually because the cells that normally do so have been destroyed by an abnormal immune reaction. In type two diabetes, adequate amounts of insulin are produced by the pancreas but the body does not respond as it should.
Insulin is responsible for moving glucose, a type of sugar used as an energy source, out of the blood stream and into cells. Without enough insulin or the ability to respond to it, blood glucose levels rise while cells are starving for energy. Glucokinase also plays an important role in responding to high blood sugar levels (more on why this is important in a moment).
And finally, one last definition. According to the Mayo Clinic:
Gene therapy is a treatment that involves altering the genes inside your body's cells to stop disease ... Gene therapy replaces a faulty gene or adds a new gene in an attempt to cure disease or improve your body's ability to fight disease.
Now on to the study that was recently published in the journal Diabetes. Scientists in Spain used gene therapy to put dogs with type one diabetes into long-term remission. One injection of "adenoassociated viral vectors of serotype 1 (AAV1) encoding for Gck and Ins," or in layman’s terms, "viruses carrying insulin and glucokinase genes" into a muscle in the dogs’ hind legs produced staggering results. Their fasting blood glucose levels were consistently normal, blood glucose was cleared from the blood stream more quickly after eating, and no episodes of low blood sugar levels during exercise were noted for more than four years after the procedure. The dogs gained weight, had lower "glycosylated plasma proteins levels" (high levels are associated with poorly controlled diabetes), and experienced "long-term survival without secondary complications." Therapy that included only the "Ins" or "Gck" genes but not both did not result in the same level of success.
I’ll admit that I was throwing the word "cure" around a little prematurely at the beginning of this post. The authors correctly use the phrase "long-term remission," since the dogs in this study were not followed out to the end of their natural life span to determine whether or not they experienced a relapse. The next phase in this research is to test gene therapy in client-owned dogs with a clinical trial. Let’s all keep our fingers crossed that the treatment will be as successful there as it appears to be in this initial study.
Dr. Jennifer Coates