Diabetes peril for developing children.

Diabetes peril for developing children

Traditionally, insulin-dependent diabetes has not been associated with impaired intellectual functioning in childhood. But very preliminary results of a three-year Canadian study hint that children who get Type I diabetes may have deficits in spatial or verbal skills.

Joanne F. Rovet and her colleagues at the Hospital for Sick Children in Toronto, Ontario, devised a three-year prospective study of 70 diabetic children enrolled within two months of diagnosis and 40 of their nondiabetic siblings. At the start of the study and then every year thereafter, they gave the children a battery of intelligence tests that measure spatial and verbal ability.

So far, 45 diabetics and 27 controls have completed the study. Analysis of the early data links the type of cognitive impairment observed to the child's age at the time of diagnosis. For children who get diabetes before their fifth birthday, the disease may affect parts of the brain responsible for spatial ability. Rovet and her colleagues found that compared with controls, these children performed poorly on tests measuring spatial skills. Children use spatial skills in such activities as arranging building blocks and solving arithmetic problems, Rovet notes.

For children older than 5 at the time of diagnosis, spatial ability seemed normal but the tests revealed verbal impairments. That finding suggests these children may have trouble learning new vocabulary words, Rovet says.

"Differences in age of onset and impairments observed," she says, "suggest the possibility of critical periods of brain development in terms of its sensitivity to the adverse consequences of diabetes." But these early results must be interpreted with caution, she adds. The last child to enter the study will complete the protocol in spring 1990, and the addition of later data may change the results.

Scientists still don't know whether the children's early spatial and verbal deficits will persist later in life. Researchers must study diabetic children over longer periods of time to find out if they have trouble in school or, as adults, with tasks such as a map reading or parking a car, she adds.