High Blood Sugar Decreases School Performance

From Diabetes Today, American Diabetes Association -- Dec. 22, 2004

ALEXANDRIA, Va. -- A temporary rise in blood glucose (sugar) levels in people with both types of diabetes can interfere with their ability to think quickly and solve problems, according to a study in the January issue of Diabetes Care.

Researchers at the University of Virginia Health System (UVHS) found that people who had both type 1 and type 2 diabetes performed poorly on math and verbal tests when they became hyperglycemic, a condition in which blood glucose levels are higher than normal. Symptoms of hyperglycemia include high blood glucose, high levels of sugar in the urine, frequent urination, and increased thirst. Roughly 55 percent of the people in the study showed signs of cognitive slowing or increased errors while hyperglycemic, suggesting that the consequences of hyperglycemia vary among individuals. However, among those whose cognitive performance deteriorated when blood sugar levels rose, the negative effects consistently appeared once levels reached or exceeded a threshold of 15 mmol/l or 270 mg/dl.

Because hypoglycemia (when blood glucose levels are too low) can cause dizziness and an inability to focus, many people consume large amounts of carbohydrates to avoid this state prior to school exams and other cognitive- sensitive tasks. But this study suggests that carbohydrate-loading could be counterproductive, the researchers conclude, because hyperglycemia often occurs after overeating.

"The best way to minimize any negative effects on cognitive functioning is to keep blood glucose levels tightly controlled," said lead researcher Dr. Daniel J. Cox, of the Center for Behavioral Medicine Research at UVHS. "People who have diabetes should pay careful attention to the warning signs of hyperglycemia so that they can quickly take action to treat it."

Treatment for hyperglycemia can include increasing insulin or reducing food intake.

Diabetes Care, published by the American Diabetes Association, is the leading peer-reviewed journal of clinical research into the nation's fifth leading cause of death by disease. Diabetes also is a leading cause of heart disease and stroke, as well as the leading cause of adult blindness, kidney failure and non-traumatic amputations. For more information about diabetes, visit the American Diabetes Association Web site http://www.diabetes.org or call 1-800-DIABETES (1-800-342-2383).