An experimental procedure performed soon after the diagnosis of Type 1 diabetes has led 13 people to remain free of the need to inject insulin for periods ranging from one month to three years.
These findings were published this week in the April 11 volume of The Journal of the American Medical Association. The study, which took place at a bone marrow transplantation center at the University of São Paulo in Brazil, enrolled 15 people aged 14–31 who had been diagnosed with Type 1 diabetes in the previous six weeks.
All of the study participants were treated early enough that they still had some functioning beta cells (the cells in the pancreas that produce insulin). Type 1 diabetes typically occurs when the body’s immune system mistakenly attacks and destroys these cells.
The experimental procedure, known as autologous nonmyeloablative hematopoietic stem cell transplantation (or AHSCT) consisted of “knocking out” participants’ immune systems and then “rebuilding” them with the use of participants’ own adult stem cells. First the researchers filtered these cells, called hematopoietic stem cells, from the blood of the participants. Then the participants underwent several days of chemotherapy, which shut down their immune systems and halted the immune attack on their beta cells. Next, the researchers injected each participant with a mixture of his own stem cells. This in turn generated white blood cells to build a new immune system that would not attack the remaining functional beta cells.
The procedure was performed on 15 people between 2003 and 2006, and participants continued to be observed through February 2007. The procedure failed in the first participant, possibly because steroids were used or because the participant had previously experienced diabetic ketoacidosis, a complication of diabetes caused by inadequate insulin and the resulting buildup of fat breakdown by-products in the body. Subsequent procedures left out the steroids and excluded people who had experienced diabetic ketoacidosis.
During an average of 19 months of follow-up time after the procedure was performed, the other 14 participants became free of the need for insulin injections. (Because the participants were diagnosed and enrolled in the study at different times, the length of time that they were followed and functioned without insulin varied.) One participant relapsed and required insulin injections one year after the procedure, but the remaining 13 maintained HbA1c levels (a measure of blood glucose control over time) of less than 7% on without injections. (The American Diabetes Association recommends an HbA1c goal of less than 7% for people with diabetes in general and a goal of less than 6%, which is the normal range for people without diabetes, if possible.) Serious side effects consisted of pneumonia in one participant and endocrine problems (hypothyroidism or hypogonadism) in two others.
Scientists have called this research “promising” and “provocative,” but also warn that the study had limitations. It did not use a control group and still needs to be tested on a larger scale with a longer follow-up period. Also, the mechanism by which AHSCT works to halt beta cell destruction is not completely clear. Scientists also point out that the technique would only be useful for people who have just been diagnosed with Type 1 diabetes, rather than those who have been living with the condition for some time.
Meanwhile, other researchers are also currently investigating ways of treating diabetes with cell transplants, such as by using specific immune cells, bone marrow cells, or embryonic stem cells.