Objective Evidence suggests that type 2 diabetes (T2DM) is associated with an increased risk of dementia and that glucose variability is an independent risk factor for diabetic complications.This study investigated the relationship between glucose excursion and cognitive function in aged T2DM patients.Methods A total of 248 aged T2DM patients wore a continuous glucose monitoring system (CGMS) for 3 days in order to evaluate glucose excursion,including mean amplitude of glycemic excursions (MAGE) and mean of daily difference (MODD).All subjects were evaluated with a number of accepted cognitive function tests,including the mini-mental status examination (MMSE).The relationship between MAGE and MODD and performance on these cognitive tests was assessed.Results The MAGE and MMSE score were negatively correlated,likewise with the correlation between MODD and MMSE.Liner multivariate regression analysis showed that MAGE and MODD were also negatively related to MMSE independent of age,sex,glycemic control,hypertension,smoking,or coronary heart disease history.Conclusion Glucose excursion is related to cognitive function in aged T2DM patients.Elevated glucose excursion decreased the MMSE score,which reflects general cognitive function.Thus,therapy aimed at controlling glucose excursion may be beneficial for maintaining cognitive function in aged T2DM patients.