The nature of the control of blood glucose in those with poorer glucose tolerance influences mood and cognition.

The ability to control the levels of blood glucose was related to mood and cognition. 155 adults, aged 45-85 years, without a diagnosis of diabetes, were given an oral glucose tolerance test and cognitive tests. Participants were classified according to age (41-60/61-85 years), whether they had better or poorer glucose tolerance and whether blood glucose did or did not fall below baseline values. There were two main findings. Those with poorer glucose tolerance forgot more words and had slower decision times, but only if 61 years or older. Secondly as there are reports in animal studies that inducing low levels of blood glucose values benefited cognitive performance, for the first time in humans, individual differences in the tendency to develop low levels of blood glucose were considered. In those with poor glucose tolerance a tendency for blood glucose to fall below baseline values was associated with better mood and faster working memory.