Effects of repeated hypoglycemia on cognitive function - A psychometrically validated reanalysis of the Diabetes Control and Complications Trial Data

OBJECTIVE - To test the conclusion that there is no association between multiple episodes of severe hypoglycemia and cognitive decrements by reanalyzing the data from the Diabetes Control and Complications Trial (DCCT) with psychometrically validated cognitive factors and to conduct a novel analysis of the association between individual differences in baseline cognitive ability and episodes of severe hypoglycemia documented after baseline. RESEARCH DESIGN AND METHODS - The factor structure of cognitive ability in the neuropsychological data from the DCCT study was derived. Four cognitive factors (spatial ability, processing speed, memory, and verbal ability) were extracted. Changes in patients' cognitive scores for each year of follow-up were obtained, and paired comparisons of these change scores were performed between groups experiencing zero and five or more hypoglycemic episodes. The association between cognitive ability at baseline and number of subsequent episodes of severe hypoglycemia was also examined. RESULTS - Repeated episodes of hypoglycemia were found not to be associated with cognitive decline in any of the validated cognitive factors. No significant association was found between prospectively documented numbers of severe hypoglycemic episodes and baseline cognitive ability level. CONCLUSIONS - Repeated episodes of hypoglycemia were not related to cognitive decrement, and initial mental ability level was not associated with eventual numbers of hypoglycemic episodes in this group of patients.