Injected Insulin Fails to Prevent Type 1 Diabetes
Partial results of the DPT-1 (Diabetes Prevention Trial-1) were announced on June 23, 2001, in a session at the Annual Meeting of the American Diabetes Association. More results, from another part of the study, will be available later.
This major scientific study was designed to answer the question whether prevention of diabetes is possible using injections of very low doses of insulin, or by giving insulin orally.
Giving insulin by injection did not delay nor prevent the development of type 1 diabetes in people who are at high risk.
BackgroundIn the October 17 1940 issue of the New England Journal of Medicine, Dr. Charles Best (one of the co-discoverers of insulin) and several coauthors said that insulin should be tested as protection from diabetes for relatives of people with diabetes.
Animal studies that were done in the 1980s looked promising, and a pilot study in 12 human beings showed that giving insulin delayed the onset of diabetes in 7 people, compared with the onset in 5 people who chose not to participate.
With this background in mind, the NIH, together with the American Diabetes Association, the Juvenile Diabetes Research Foundation, and corporate sponsors, banded together in an effort to answer the question: Can antigen-based therapy using insulin delay the onset of diabetes in relatives of people with type 1 diabetes?
Screening for participation in the study
The first step in the study was finding people who were thought to be at high risk of developing diabetes in the near future. Eligibility requirements included first-degree relatives of people with diabetes who were between the ages of 3 and 45, or second-degree relatives between the ages of 3 and 20.
Screening consisted of measurement of islet-cell antibodies. If the antibody test was positive, metabolic testing was performed using Intravenous Glucose Tolerance Test (IVGTT) and Oral Glucose Tolerance Tests (OGTT). Depending on the results of these, subjects were assigned to one of two study groups.
Design of the Study
The DPT-1 study included two major study groups:
- Injections of insulin (parenteral therapy) to subjects whose risk of developing diabetes in the next 5 years is thought to be 50% or higher. Results of this part of the study were presented June 23.
- Oral administration of insulin to subjects whose risk of developing diabetes in the next 5 years is thought to be between 26-50%. This part of the study is ongoing, and indeed recruiting of additional subjects continues.
Patients were enrolled over several years, with nearly 100,000 people undergoing initial screening of their antibody status over the course of seven years, and after further evaluations (See above), 339 subjects met the study's criteria for parenteral therapy (positive antibody testing, abnormal first-phase insulin release, and glucose tolerance tests that did not show diabetes).
Active treatment was 4 days of intravenous insulin annually, with daily injections of 0.25 units/kg/day of Ultralente insulin. The control group received no treatment. Patients were randomized into either active or control groups.
- Of the people who were initially screened and had positive antibodies, 11.2% already had diabetes (based on blood sugar testing).
- The results of the parenteral insulin part of the DPT-1 study showed no difference in the chances of people developing diabetes if they took low-dose insulin by injection, compared with people who did not receive insulin. Sixty percent of both the treated group, and the untreated group, developed diabetes within 5 years. Children under the age of 13 progressed to diabetes more rapidly than kids post-puberty or adults.
- 73% of those who developed diabetes during the DPT-1 were asymptomatic at the time of their diagnosis, and the diagnosis was picked up only because they were in the study. This shows that it is indeed possible to diagnose type 1 diabetes before symptoms develop.
Speculation on why this study failed to find a difference centered around the thought that perhaps the patients studied were too far along in the process of developing diabetes to be able to reverse the process. Or perhaps the dose of insulin was wrong -- only one dose was tested.
Results from the Oral Part of the Study are Still Pending
It must be noted that the DPT-1 has reported the results of one arm of the study (insulin-by-injection). As mentioned above, the second arm of the study (using oral insulin) is still proceeding. This arm of the study will be evaluating patients who are presumably earlier in the beta-cell destruction process, and therefore might be more likely to respond to the intervention, and have a delay in the onset of diagnosis.
- Insulin Injections Fail To Prevent Type 1 Diabetes. (NIH Press Release)
- Low-Dose Insulin Does Not Prevent Type 1 Diabetes Onset. (Free Medscape membership required)
Posted June 24, 2001
Last Updated: Thursday August 29, 2002 20:59:48
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