First Large Trial of Type I Diabetes Prevention Approach Still Under Way
PITTSBURGH – Early findings from the first large international trial to try to prevent type I diabetes show that infants at risk for the disease who were fed a special baby formula that lacks complex cow milk proteins still made antibodies against the insulin-producing cells of the pancreas by the time the youngest children studied were six years old. Previous studies suggested the experimental formula might prevent the development of the auto-antibodies, which represent inflammatory changes in the organ.
But that doesn’t mean the children will definitely develop type I diabetes, also known as insulin-dependent diabetes mellitus (IDDM), as they get older, caution researchers at Children’s Hospital of Pittsburgh of UPMC, which is the coordinating center for the American arm of the study. The findings were published in the Journal of the American Medical Association.
In type I diabetes, the body’s immune system attacks its own pancreatic beta cells, which make insulin to regulate blood sugar levels. That autoimmune process is thought to start very early in life, explained U.S. principal investigator Dorothy Becker, MBBCh, professor of pediatrics at Children’s Hospital and the University of Pittsburgh School of Medicine.
Some smaller studies and animal experiments have shown that exposure during infancy to complex foreign proteins, such as the cow milk proteins in conventional baby formula, is associated with the presence of these autoimmune antibodies in children who have a parent or sibling with the condition and other indications of genetic risk.
“This has been a controversial issue, in part because different natural history studies have come to different conclusions,” Becker said. “We hope that when our intervention trial concludes in February 2017, which is when all the participating children will be at least 10 years old, we should have enough evidence to say whether or not this experimental formula can prevent them from getting Type I diabetes.”
From 2002 to 2007 at 78 study sites in 15 countries, the “Trial to Reduce IDDM in the Genetically at Risk,” or TRIGR, research group randomly assigned 1,078 high-risk infants to be weaned to a “hydrolyzed” formula made almost completely with smaller, less complex casein proteins and 1,081 to get conventional formula, which is made with 80 percent cow milk proteins and 20 percent of the hydrolyzed casein protein.
The two formulas were similar in taste and smell so that neither the parents nor researchers could tell the difference between them. Each baby’s parents made their own decisions about breastfeeding and age of weaning to formula.
Blood samples from the umbilical cord and at three, six, nine, 12, 18 and 24 months of age, and yearly after that to age 10, were tested for antibody levels. After an average of seven years of follow-up — the youngest participants are now six — the researchers found no differences in antibody levels between the two groups.
“This tells us that the kind of formula the baby drinks doesn’t affect the inflammatory changes going on in the pancreas,” Becker said. “But it doesn’t tell us yet whether they will develop diabetes. In one animal study, mice that were fed the experimental formula had the inflammatory markers, but diabetes was almost totally prevented using the same experimental formula. That could be the case with these children, too.”
The TRIGR study group includes the Data Management Unit and researchers from six centers in the U.S., centers in Scandinavia led by the University of Helsinki, and centers throughout Canada, Australia and Europe.
The project was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Special Statutory Funding Program for Type 1 Diabetes Research and Digestive and Kidney Diseases, both part of the National Institutes of Health (grant numbers HD040364, HD042444 and 338 HD051997); the Canadian Institutes of Health Research; the Juvenile Diabetes Research Foundation International; and the Commission of the European Communities.