Mom's Infections Tied to Lower Diabetes Risk in Child
19 February, 2014
ISLAMABAD: Among girls at increased risk of type1 diabetes, those whose mothers had colds or certain other infections during pregnancy might be less likely to develop diabetes, new study findings suggest.
Researchers found that in early childhood, these children were 80 percent less likely than other at-risk girls to develop autoantibodies -- that is, antibodies targeting "self" proteins -- that precede type 1 diabetes.
All children in the study were considered at risk of the disease because a parent or sibling had it, or because they carried certain genetic characteristics. Exactly why some maternal infections might confer protection against type 1 diabetes, and why the benefit was seen only in girls, are unclear, according to the study authors.
Unlike the much more common type 2 diabetes, type 1 is an autoimmune disorder. It arises when the immune system mistakenly attacks the pancreatic cells that make insulin, a hormone that shuttles the sugar from food into cells to be used for energy. People with type 1 diabetes must take daily injections of insulin to compensate for the lack of naturally produced hormone.
The disease is usually diagnosed in childhood; family history is a risk factor, as are certain genetic variations that govern immune function. But these factors only mean a person has a greater susceptibility to developing type 1 diabetes.
Researchers are trying to tease out the environmental "triggers" that set off the abnormal immune attack against insulin-producing cells.
The new study looked at whether maternal infections during pregnancy, or other early exposures to viruses and bacteria, might sway a genetically at-risk child's odds of developing type 1 diabetes. Besides maternal infections, researchers studied newborn infections, and whether children went to daycare or lived with pets.
According to the study authors, led by Dr. Lars C. Stene of the University of Colorado Health Sciences Center, there are two potential, opposite roles for infections in type 1 diabetes.
On one hand, they note in the November issue of Diabetes Care, viruses have been seen as "prime suspects" in triggering the disease. It's thought that some as yet unidentified viral infections might cause the immune system to go awry and attack pancreatic cells.
On the other hand, studies have found that early exposure to bacteria -- through household pets or daycare attendance, for example -- might protect children from developing allergies and asthma. These conditions are also caused by an abnormal immune reaction, though not the same as the one involved in type 1 diabetes. Some research has suggested that early exposure to certain bugs might similarly reduce the risk of diabetes.
Stene's team found that among nearly 1,300 children at risk for type 1 diabetes, those whose mothers said they'd had an infection during pregnancy were half as likely to have antibodies against their own insulin-producing cells. The maternal infections were mostly respiratory or gastrointestinal.
Further analysis showed the effect was only true for girls, who were 80 percent less likely than girls whose mothers reported no infections to have the antibodies in their blood. None of the other environmental factors studied turned out to be important.
The reason for the connection, and why it was seen only in girls, is unknown, Stene and his colleagues write. One theory is that early exposure to various infections alter the developing immune system in such a way to protect against both allergic conditions and autoimmune diseases. It's also possible, the study authors note, that maternal antibodies play a role.