Severe Hypos May Impair Spatial Memory

In a recent journal article, researchers notedthat early exposure to and high frequencyof severe hypoglycemia “negatively affectslong-term spatial performance” in childrenwith type 1.

Washington University School of Medicineresearchers in St. Louis, Missouri, combineddata from three independent studies toobtain a sample of 103 children aged 6-18years with type 1 along with 60 nondiabeticcontrol subjects.

“We found that repeated severe hypoglycemia(more than three episodes) reducedlong-term spatial delayed responseperformance, particularly when severehypoglycemic episodes began before theage of 5 years,” write the researchers. “Age of type 1 diabetes onset and estimates ofchronic hyperglycemia did not influenceperformance.”

Diabetes Care, October 2005

What is Spatial Memory?

Spatial memory is the memory function that recordsinformation about one’s environment and its spatialorientation. For example, spatial memory is required inorder for a person to navigate a familiar city, just as a rat’sspatial memory is needed to learn the location of food atthe end of a maze.


Tamara Hershey, PhD, and Neil White, MD, were researchers on the memory study.

What are some serious repercussions ofdecreased spatial memory function?

Spatial memory is used in daily life in numerousways. For instance, children may use spatialmemory when they recall where they puttheir lunchbox when they got home, or whenthey learn the location of their cubby in a newclassroom. However, our study does not addresswhether these kinds of everyday memory taskswere affected by severe hypoglycemia. Whetherperformance on our laboratory memory taskpredicts memory function in the context ofeveryday life remains an important area forfurther research.

What can parents of type 1 kids do tohelp alleviate severe hypos?

The first step to avoidance of severehypoglycemia in children with type 1 diabetesis to set appropriate goals, including bloodglucose targets that minimize the risk of evenmild hypoglycemia. This is especially true at anage when hypoglycemia recognition is not yetfully developed (“age-associated hypoglycemiaunawareness”). Many think that this age isless than 6-7 years old, but it must be veryindividualized.

Second, overinsulinization is inadvisable andof no demonstrated benefit. Regardless of thechosen insulin regimen, the doses should be atthe lowest level, which is required to accomplishthe blood glucose target. Higher dose thatresult in the need for repeated treatment ofhypoglycemia should be avoided.

Third, although some regimens—such as usingan insulin pump or taking Lantus as comparedto suppertime or nighttime NPH—have beenshown to reduce hypoglycemia—especiallynighttime hypoglycemia—it needs to berecognized that there is no one regimen that canbe recommended for all subjects. Attention toindividual variation in responses to treatment isa key element of success.

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