Very Low Blood Sugar Affects Memory in Children

NEW YORK (Reuters Health) - Episodes of extremely low blood sugar (hypoglycemia), particularly at an early age, can have an impact on spatial memory performance in children with type 1 diabetes, according to the results of a new study.

As lead investigator Dr. Tamara Hershey told Reuters Health, "this study tests and supports a common hypothesis that severe hypoglycemia experienced early in life is riskier for cognitive function than severe hypoglycemia experienced later in life. We focused only on a spatial memory task which has previously been shown to be sensitive to repeated hypoglycemia."

Hershey, of Washington University School of Medicine, St. Louis, Missouri, and colleagues studied data from three independent studies involving 103 diabetic children and 60 children without diabetes between 6 and 18 years old. The findings are published in the journal Diabetes Care.

The 2-hour battery of cognitive measures included evaluation of short (5-second) and long (60-second) spatial memory and reactions. This involved recalling locations and responding to shapes shown on a computer screen.

Children who had had more than three episodes of severe hypoglycemia showed reduced performance on the longer-delayed spatial response test. This was particularly the case when severe hypoglycemic episodes began before the age of 5 years.

The age at which type 1 diabetes developed and estimates of chronic high blood sugar levels did not influence performance.

The researchers conclude that "the developing brain of very young children may be more vulnerable than the brain of older children to the negative effect of severe hypoglycemia on longer-term spatial memory."

However, Hershey added that "more research needs to be done on how this effect relates to everyday life. This information could eventually be used when assessing the benefits and risks of tight (sugar) control...at very young ages."

SOURCE: Diabetes Care, October 2005.