Serum Sulfate and Brain Function in Diabetic Encephalopathy

Inclusion criteria

• Age 45-75 years, no restriction on sex; patients with type 2 diabetes mellitus who meet the current American Diabetes Association (ADA) Standards of Care in Diabetes or the World Health Organization (WHO) diagnostic criteria for diabetes, with a confirmed disease duration ≥ 6 years.
• Cranial plain magnetic resonance imaging (MRI; sequences including at least T1WI, T2WI, and FLAIR) with a radiological report indicating age-inappropriate brain atrophy (e.g., ventricular enlargement, widened sulci). Concomitant prior cerebral infarction or cerebral small vessel disease changes (e.g., lacunar infarction, white matter hyperintensities, etc.) are allowed. Other major structural causes that may lead to cognitive impairment, such as cerebral hemorrhage and space-occupying lesions, are excluded. Patients with acute cerebral infarction at least 2 weeks after onset, with stable vital signs and metabolic status, who are able to complete the MoCA assessment and MRI examination, are allowed.
• Montreal Cognitive Assessment (MoCA) score < 26.
• Education level of primary school or above; able to communicate well with the investigators and comply with all study requirements.
• Voluntarily participate in this study and provide signed informed consent.

Exclusion criteria

• Patients with type 1 diabetes, gestational diabetes, other specific types of diabetes, or participants with unknown diabetes status.
• Cognitive impairment caused by other definite etiologies (e.g., Alzheimer's disease, Lewy body dementia, frontotemporal dementia, central nervous system infection, severe traumatic brain injury, poisoning, etc.).
• Severe infection, major trauma, or surgery within 3 months; active malignancy (except localized skin cancer); or acute or severe systemic diseases that may significantly affect metabolic status or cognitive function.
• Major depressive disorder, schizophrenia, or other psychiatric disorders or delirium that may affect the assessment of cognitive function.
• Severe hepatic or renal insufficiency (e.g., ALT or AST > 3 times the upper limit of normal, eGFR < 30 mL/min/1.73 m²).
• Severe hearing or visual impairment, MRI contraindications, or any other condition that prevents cooperation with the examinations.