Blood glucose levels before and after cognitive testing in diabetes mellitus.

The primary indices of diabetes mellitus (DM), including hemoglobin A1c (HbA1c) and fasting glucose, appear to be only moderately predictive of the cognitive impairments exhibited by patients with DM. There is evidence that in DM the ability to utilize glucose is compromised and the authors hypothesized that this difficulty might be relevant to the study of cognitive function in DM. Thus, the authors examined the relationship between cognitive performance and changes in peripheral glucose from the start to the conclusion of cognitive testing. Individuals who showed decreased glucose levels from the start to the conclusion of cognitive testing performed significantly better than those exhibiting moderate to slight increases in glucose levels from the start to the conclusion of testing. Apparently, the putative utilization of blood glucose rather than the glucose levels prior to or following a cognitive challenge is associated with better cognitive performance primarily on more complex cognitive tests. This brief and inexpensive test of changes in glucose levels has potential clinical implications for assessing cognitive status in DM.