On paper, preventing type I diabetes mellitus looks promising. Previous studies have shown that insulin prophylaxis may protect the insulin-producing islet cells of at-risk patients, delaying or preventing symptom onset.

But will it work in practice? To answer this question, the National Institutes of Health and a consortium of public and private organizations have launched the Diabetes Prevention Trial, Type 1 (DPT-1). MUSC is one of about 35 centers in the nation offering the protocol.

“Through DPT-1, we’re trying to see if we can delay, or even prevent onset of insulin dependent diabetes (IDDM) by maintaining at-risk patients on low-dose oral or injected insulin,” says Steven Willi, M.D., the pediatric endocrinologist who heads MUSC participation in the study.

“Study participation offers patients free testing and counseling, as well as the possibility of avoiding the disease entirely. At the very least, the ongoing screening program will help identify IDDM onset at the earliest possible stage so treatment can start before a lot of systemic damage has occurred.”

Family history

Patients can be referred for study testing if they are either:

• 3-45 years of age and their family history includes a sibling, child or parent with IDDM, or
• 3-20 years of age and have a cousin, uncle/aunt, nephew/niece, grandparent or half-sibling diagnosed with IDDM.

Patients who test positive for islet cell antibodies will be randomized to either a low-dose insulin treatment or control group. Those receiving insulin can participate in either an oral insulin trial or an injected insulin trial.

“The oral insulin group will be given either placebo or insulin crystal capsules,” says Willi. “But, for ethical reasons, there’s no placebo associated with the injected insulin trial—patients receive insulin or do not receive injections.”

All patients will be monitored closely for signs of IDDM onset, and in addition, the injected insulin group will be admitted to the MUSC Medical Center for four days of inpatient insulin therapy each year.

Mechanism of action

“There are several theories as to why low-dose insulin might prevent IDDM,” says Willi. “One possibility is that the insulin desensitizes the immune system and prevents it from attacking the insulin-producing ß-cells. It’s also possible that the insulin gives the islet cells a rest that helps preserve their function. Whatever the mechanism, we’ve seen the positive effects in small studies, and we hope this trial translates those effects to a larger population.”

Willi stresses that patients should remain under the ongoing care of their referring physicians. Physicians will be kept informed of test results and outcomes of study participation for their patients.

Juvenile diabetes among African American: Type 1 or 2?

Many African-American juveniles who are thought to have type 1 insulin dependent diabetes mellitus (IDDM) may actually have a form of type 2 non-insulin dependent diabetes (NIDDM). These NIDDM individuals may be hard to identify on the basis of metabolic parameters alone, but a study at the MUSC Medical Center can help.

“In a group of African-American juveniles 18 years of age and younger, we found 57 percent with IDDM and 40 percent (29) with an atypical form of early-onset diabetes with persistent C-peptide production and negative islet cell antibodies,” said Willi.

“These young men and women may be receiving inappropriate therapy, so we designed a study to help identify them and steer them onto the right therapeutic course. We also want to describe this phenotype in African-American children.”

Patients referred and accepted into this study undergo comprehensive islet cell antibody testing and serial evaluation of C-peptide production. This expensive series of tests is free to the patient, and the referring physician will be notified of findings.

For consultation or referrals, call MUSC Health Connection at 792-1414.

Editor's note: The article is reprinted from MDialogue newsletter, a physician liaison program publication.