Inclusion and exclusion criteria

Inclusion criteria: (I) T2DM met the ADA diagnostic criteria (see Method section for details); (II) age: 45–74 years old; (III) education level: low (6–12 years) or high (>12 years); (IV) the clinical manifestations of memory deficit, and confirmed by others; (V) had the visual and auditory ability to take neuropsychological test.

Exclusion criteria: (I) other types of diabetes; (II) younger than 45-year-old or older than 75; (III) less than 6 years of education; (IV) patients who were not able to complete neuropsychological scale screening, such as speech impairment, hearing loss and reluctant to cooperate then; (V) combined with metabolic diseases that may affect cognitive function temporarily, such as acute carbohydrate metabolic events in the last 3 months, including severe hypoglycemia, diabetic ketoacidosis, diabetic hyperglycemia hypertonic coma, hypothyroidism, etc.; (VI) combined with head trauma that might affect cognitive function, cerebral intake, mental and neurological disorders such as depression, anxiety, delirium, severe lung or kidney diseases, history of heart failure, malignant tumors, etc.; (VII) a history of drug dependence/abuse; (VIII) used the following drugs in the previous month: antidepressant drugs, anti-Parkinson drugs, anti-epileptic drugs, sedative hypnotic drugs, etc.; (IX) using cognitive dysfunction medications such as donepezil, memantine, etc.