AIMS/INTRODUCTION: As the prevalence of diabetes increases with age, the number of elderly patients with diabetes in Japan, a super-aged society, continues to increase. We conducted a survey to investigate the extent to which outpatients with diabetes recognize dementia as a complication of diabetes. MATERIALS AND METHODS: A questionnaire was distributed among 777 patients with diabetes to investigate their awareness of dementia and its risk factors. Among these, the Mini-Mental State Examination was also administered to patients over 65 years of age who wished to undergo a cognitive function test among those who participated in the questionnaire survey to examine the factors leading to a decline in cognitive function. RESULTS: 458 patients selected poor blood glucose control and 176 selected hypoglycemia as the condition that rendered patients susceptible to dementia. Regarding the risk factors for suspected cognitive decline, the risk increased in the following order: old age
lack of knowledge about dementia
and treatment with diet/exercise, oral hypoglycemic agents/Glucagon-like peptide-1, and insulin. Regarding the relationship between cognitive decline and blood glucose control, the risk of suspected cognitive decline increased in the following order: within the standard value, above and below the standard values, in terms of the level of glycated hemoglobin set in "Blood Glucose Control Target for Elderly Diabetes" defined by the Japan Geriatrics Society and the Japan Diabetes Society. CONCLUSIONS: When examining and treating diabetes, it may be pertinent to instruct older adults on target HbA1c levels based on their condition.