Impact of glucose metabolism and birth size on cognitive performance in elderly subjects

AimsWe aimed to investigate the impact of diabetes and impaired glucose tolerance on cognitive performance and to explore the association between birth weight and cognitive performance among diabetic subjects.MethodsWe performed a standard oral glucose tolerance test and a computerised test for assessment of cognitive performance (CogState®) in 1243 subjects; 173 of them had type 2 diabetes. At the time of cognitive testing the mean age of the subjects was 64 years. Subjects with type 1 diabetes or a history of stroke were excluded.ResultsSubjects with known diabetes performed significantly poorer in cognitive tasks measuring visual attention, working memory and episodic learning than subjects with normal glucose tolerance. Subjects with newly diagnosed diabetes or milder impairments in glucose regulation did not differ from the normoglycaemic group. A low birth weight enhanced the association between diabetes and poor performance in the working memory and episodic learning tasks.ConclusionsPoorer cognitive performance was associated with known type 2 diabetes but not with newly diagnosed diabetes or milder impairments in glucose regulation. Low birth weight was found to be an additional vulnerability factor enhancing cognitive decline in diabetic subjects.