The goal of this observational study is to learn about the relationship between sulfate ion levels in the blood and brain function in people with diabetic encephalopathy, a diabetes-related brain condition that can affect thinking and memory. The main questions it aims to answer are:
1. Are blood sulfate ion levels related to memory and thinking test scores? 2. Are blood sulfate ion levels related to the severity of brain shrinkage (brain atrophy) seen on MRI? 3. Do sulfate ion levels and their relationship with thinking and memory differ among people with different levels of long-term blood sugar control? Researchers will compare participants grouped by long-term blood sugar control (based on HbA1c, a blood test that reflects average blood sugar over the past 2-3 months) to see whether sulfate ion levels and their associations with brain function differ.
Participants will:
1. Give a blood sample to measure sulfate ion levels, HbA1c, and neurofilament light chain (NfL), a marker of nerve damage. 2. Complete the Montreal Cognitive Assessment (MoCA), a test of memory and thinking, and questionnaires about daily living skills. 3. Have a brain MRI scan to assess brain shrinkage, unless a recent scan within the past 6 months can be used. 4. Provide information about their diabetes and medical history. This is a cross-sectional study, so participants will be assessed once at enrollment. No treatment or intervention is given. About 220 adults aged 45-75 years with type 2 diabetes and diabetic encephalopathy will take part.
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.
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.
Adults aged 45-75 years of either sex with T2DM for ≥6 years and diabetic encephalopathy, defined as MoCA \<26 plus MRI evidence of age-inappropriate brain atrophy after excluding other structural causes. Both sexes; primary school education or above; able to complete MoCA/MRI; signed informed consent. Exclusions include type 1/gestational/other diabetes, other causes of cognitive impairment, recent severe illness/trauma/surgery, active malignancy, major psychiatric disorders, severe hepatic/renal insufficiency, and MRI contraindications. Approximately 220 participants will be enrolled.
Cohort
Cross-sectional
This study does not involve any treatment or intervention.
Other interventionThis study does not involve any treatment or intervention.
Serum sulfate ion levels
Serum sulfate ion concentration, measured in mmol/L by ion chromatography. Analyzed as a continuous variable; no predefined minimum or maximum. Higher values indicate higher serum sulfate ion levels.
Long-term glycemic control (HbA1c)
Glycated hemoglobin (HbA1c) level, measured as a percentage (%) by a standardized assay. Reflects average blood glucose over the preceding 2-3 months. Analyzed as a continuous variable; higher values indicate poorer long-term glycemic control.
Brain function: MoCA total score
Total score on the Montreal Cognitive Assessment (MoCA). Scores range from 0 to 30, with higher scores indicating better cognitive function.
Brain atrophy assessed by cranial MRI
Brain atrophy assessed on cranial MRI (T1WI, T2WI, FLAIR) by experienced radiologists using standardized visual rating scales (e.g., MTA, GCA, and/or Evans index). Severity graded as none, mild, moderate, or severe, or per the selected validated scale; higher grades indicate more severe atrophy (worse outcome).
Barthel Index total score
Total score on the Barthel Index, a scale used to assess functional independence in basic activities of daily living (ADL). Scores range from 0 to 100, with higher scores indicating greater independence (better outcome).
Instrumental Activities of Daily Living Scale (IADL) score
Total score on the Lawton Instrumental Activities of Daily Living Scale (IADL), which assesses independence in complex daily activities such as telephone use, shopping, food preparation, housekeeping, laundry, transportation, medication management, and handling finances. Scores range from 0 to 8, with higher scores indicating greater independence (better outcome).
Serum neurofilament light chain (NfL) level
Serum neurofilament light chain (NfL) level, measured in pg/mL by a validated immunoassay. Higher levels indicate greater neuroaxonal injury (worse outcome). Analyzed as a continuous variable.
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