Transcutaneous Auricular Vagus Nerve Stimulation in Type 2 Diabetes With Mild Cognitive Impairment

Efficacy of Transcutaneous Auricular Vagus Nerve Stimulation in Patients With Type 2 Diabetes and Mild Cognitive Impairment: A Single-Center, Randomized, Double-Blind, Sham-Controlled Clinical Trial

This study is a 24-week, single-center, randomized, double-blind, sham-controlled, parallel-group clinical trial. A total of 38 patients with type 2 diabetes and mild cognitive impairment were enrolled and randomly assigned in a 1:1 ratio to either the treatment group (receiving active transcutaneous auricular vagus nerve stimulation) or the sham control group (receiving sham transcutaneous auricular vagus nerve stimulation). The primary objective of this study is to evaluate the potential disease-modifying effects of transcutaneous auricular vagus nerve stimulation on cognitive impairment in patients with type 2 diabetes.

Study Overview

• Status: Not yet recruiting
• Conditions: Type 2 Diabetes; Mild Cognitive Impairment
• Intervention / Treatment: Device: active transcutaneous auricular vagus nerve stimulation; Device: sham transcutaneous auricular vagus nerve stimulation

Detailed Description

This study is a 24-week, single-center, randomized, double-blind, sham-controlled, parallel-group clinical trial aimed at investigating the potential disease-modifying effects of transcutaneous auricular vagus nerve stimulation (taVNS) on cognitive impairment in 38 patients with type 2 diabetes mellitus (T2DM) complicated by mild cognitive impairment. Participants will be randomly assigned in a 1:1 ratio to receive either active taVNS (stimulation frequency: 20 Hz pulses for 10 seconds and 100 Hz pulses for 50 seconds per minute; 30 minutes per session, twice daily) or sham stimulation for 5 days per week. All participants will continue to receive treatment based on their original glucose-lowering therapies. The primary objective of the study is to evaluate improvements in cognitive function, while secondary endpoints include structural and functional brain changes, metabolic improvements, neurodegenerative biomarkers, and safety outcomes.

Participants will undergo comprehensive cognitive and metabolic assessments at baseline, followed by a safety visit at Week 12 to monitor adverse events, treatment adherence, and metabolic parameters. The comprehensive evaluation at Week 24 will include cognitive assessments, neuroimaging, and metabolic profiling. During the study period, investigators will conduct weekly follow-ups via telephone or WeChat, and participants will attend monthly in-clinic visits to complete examinations such as capillary blood glucose, blood pressure, and heart rate, as well as to be inquired about treatment adherence and adverse reactions. All rationales for decision-making and efficacy evaluations must be thoroughly documented.

• Study Type: Interventional
• Enrollment (Estimated): 38
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jianguo Ruan, MD; Phone Number: 86-25-83-106666; Email: medrjg@163.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Type 2 diabetes mellitus
2. Meets criteria for mild cognitive impairment
3. Aged 40 to 75 years, with no gender restrictions
4. HbA1c levels between 6.5% and 9.0%
5. At least 6 years of formal education
6. Able to cooperate with and complete all cognitive and functional assessments
7. Right-handed
8. Voluntary provision of written informed consent

Exclusion Criteria:

1. Concomitant use of GLP-1 receptor agonists, Alzheimer's disease medications, anti-Parkinson's medications, antiepileptic drugs, or antipsychotic drugs within 3 months prior to screening
2. Presence of dementia-related neurological disorders; current or history of clinically significant psychiatric disorders within the past 2 years (e.g., schizophrenia, bipolar disorder, major depressive disorder, generalized anxiety disorder, personality disorders)
3. CNS diseases, including traumatic brain injury, intracranial hemorrhage, acute cerebral infarction, etc
4. Severe sinusitis, nasal and sinus polyps, space-occupying lesions such as skull base or nasopharyngeal tumors; congenital diseases or history of trauma of the nose, maxillofacial region, or skull base that affect olfactory function; presence of upper respiratory tract infection symptoms (e.g., nasal congestion, rhinorrhea, fever) on the day of the MRI scan
5. Acute complications of diabetes, including diabetic ketoacidosis, hyperglycemic hyperosmolar state, hypoglycemic coma, etc
6. Severe impairment of major organ function (e.g., heart, liver, kidneys), including any of the following: ALT and/or AST > 3×ULN. eGFR < 45 mL/min/1.72 m² (CKD-EPI). History of unstable angina, myocardial infarction, or NYHA Class II or higher heart failure within 3 months prior to screening
7. Concurrent major illnesses, such as active or untreated malignancies, or malignancies in clinical remission for less than 5 years.
8. Contraindications for MRI scans (e.g., implanted metallic prostheses, claustrophobia); presence of cardiac pacemakers or other implantable medical devices; severe infection or ulceration of the auricular skin
9. Pregnant or lactating women
10. History of alcohol abuse, defined as an average weekly alcohol consumption exceeding 21 units for males and 14 units for females (1 unit = 360 mL of beer, 150 mL of wine, or 45 mL of distilled spirits/liquor)
11. Any other conditions or factors that, in the opinion of the investigator, may confound the efficacy or safety evaluation of the study, making the participant unsuitable for enrollment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: active taVNS; After disinfecting the stimulation sites (cymba conchae, cavum conchae, and earlobe), the auricular stimulation electrodes will be attached. For the active stimulation group, the actual functional electrodes delivering the current are positioned at the cymba conchae and cavum conchae. The stimulation parameters are set as follows:(1) Dense-disperse wave, with a stimulation frequency consisting of 20 Hz pulses for 10 seconds and 100 Hz pulses for 50 seconds per minute, and a pulse width of 0.2 ms ± 30%;(2) Stimulation intensity ranging from 4 to 6 mA, adjusted according to the individual patient's tolerance;(3) 30 minutes per session, twice daily;(4) 5 days per week, for 24 weeks.	Device: active transcutaneous auricular vagus nerve stimulation; After disinfecting the stimulation sites (cymba conchae, cavum conchae, and earlobe), the auricular stimulation electrodes will be attached. For the active stimulation group, the actual functional electrodes delivering the current are positioned at the cymba conchae and cavum conchae. The stimulation parameters are set as follows:(1) Dense-disperse wave, with a stimulation frequency consisting of 20 Hz pulses for 10 seconds and 100 Hz pulses for 50 seconds per minute, and a pulse width of 0.2 ms ± 30%;(2) Stimulation intensity ranging from 4 to 6 mA, adjusted according to the individual patient's tolerance;(3) 30 minutes per session, twice daily;(4) 5 days per week, for 24 weeks.
Sham Comparator: sham taVNS; After disinfecting the stimulation sites (cymba conchae, cavum conchae, and earlobe), the auricular stimulation electrodes will be attached. For the sham stimulation group, the actual functional electrodes delivering the current are positioned at the earlobe. The stimulation parameters are set as follows:(1) Dense-disperse wave, with a stimulation frequency consisting of 20 Hz pulses for 10 seconds and 100 Hz pulses for 50 seconds per minute, and a pulse width of 0.2 ms ± 30%;(2) Stimulation intensity ranging from 4 to 6 mA, adjusted according to the individual patient's tolerance;(3) 30 minutes per session, twice daily;(4) 5 days per week, for 24 weeks.	Device: sham transcutaneous auricular vagus nerve stimulation; After disinfecting the stimulation sites (cymba conchae, cavum conchae, and earlobe), the auricular stimulation electrodes will be attached. For the sham stimulation group, the actual functional electrodes delivering the current are positioned at the earlobe. The stimulation parameters are set as follows:(1) Dense-disperse wave, with a stimulation frequency consisting of 20 Hz pulses for 10 seconds and 100 Hz pulses for 50 seconds per minute, and a pulse width of 0.2 ms ± 30%;(2) Stimulation intensity ranging from 4 to 6 mA, adjusted according to the individual patient's tolerance;(3) 30 minutes per session, twice daily;(4) 5 days per week, for 24 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Montreal Cognitive Assessment Scale (MoCA) score	The MoCA is a comprehensive endpoint focusing on the cognitive domain. It integrates multidimensional assessments of core cognitive functions (including subscale scores for visuospatial/executive function, naming, attention, language, abstraction, delayed recall, and orientation), yielding a total score range of 0-30.The calculation formula is:MoCA Score = Subscale Scores+ Educational Correction(Note: If the participant's formal education is ≤12 years, 1 point is added to the sum of the subscale scores, with the maximum total score capped at 30).Lower MoCA scores indicate more severe global cognitive impairment in the participant.	Baseline, and Week 24

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in score of Mini-Mental State Examination (MMSE)	The MMSE contains a total of 30 items that assess orientation, registration, attention and calculation, recall, and language, with a score range from 0 to 30. Generally, a higher MMSE score reflects a better cognitive function.	from baseline to week 24 of treatment
Changes in total score of RBANS	The RBANS (Chinese version) is a brief neuropsychological screening battery with established test-retest reliability and age-appropriate normative data, which consists of 12 task tests assessing 5 cognitive domains, namely immediate memory, visuospatial/ constructional, language, attention and delayed memory, with a score range from 40 to 160. A higher RBANS score reflects a better global cognitive function.	from baseline to week 24 of treatment
Change in the RBANS index score of immediate memory	The RBANS (Chinese version) is a brief neuropsychological screening battery with established test-retest reliability and age-appropriate normative data. The RBANS includes 12 sub-tests that generate five age-adjusted index scores and a total score. The five indices include immediate memory (consisting of list learning and story memory tests), visuospatial/constructional domain (consisting of figure copying and line orientation tests), language (consisting of picture naming and semantic fluency tests), attention (consisting of digit span and coding tests) and delayed memory (consisting of list recall, story recall, figure recall and list recognition tests). Generally, a higher index score reflects a better cognitive subdomain function.	from baseline to week 24 of treatment
Change in the RBANS index score of visuospatial/constructional	Measurements and instruments are the same as the RBANS index score of immediate memory.	from baseline to week 24 of treatment
Change in the RBANS index score of language	Measurements and instruments are the same as the RBANS index score of immediate memory.	from baseline to week 24 of treatment
Change in the RBANS index score of attention	Measurements and instruments are the same as the RBANS index score of immediate memory.	from baseline to week 24 of treatment
Change in the RBANS index score of delayed memory	Measurements and instruments are the same as the RBANS index score of immediate memory.	from baseline to week 24 of treatment
Change in aggregate time to test completion for Trail Making Test (TMT)	The TMT is a validated timed measure of processing speed, which consists of part A and part B (TMT-A and TMT-B). The time limits for performing the TMT-A and TMT-B are 180 and 300 seconds, respectively. Processing speed is estimated by the aggregate time in seconds to complete TMT-A and TMT-B such that less time indicate faster processing speed.	from baseline to week 24 of treatment
Change in aggregate time to test completion for Victoria Stroop Color-Word Test	The Victoria Stroop Color-Word Test is a well-known measure of executive function. There are three indices including Stroop-dot, Stroop-word and Stroop-color word in the test. The color task consists of colored dots; the word task comprises ordinary words that are unrelated to the meaning of color; the color-word task consists of words written in color that indicate the meaning of the color, but the color of these words differs from the meaning of the word itself. The participants were asked to quickly read the color of the dots or Chinese words on the cards. The sum of consuming time taken to read the three cards is used as an index of executive function performance. Less time indicates better executive function.	from baseline to week 24 of treatment
Change in Total Brain Volume	The change in total brain volume evaluated by structural MRI from baseline to Week 76 will be compared between the treatment group and the placebo group.	from baseline to week 24 of treatment
Change in Total White Matter Volume	The change in total white matter volume evaluated by structural MRI from baseline to Week 76 will be compared between the treatment group and the placebo group.	from Baseline to Week 24 of treatment
Change in Total Gray Matter Volume	The change in total gray matter volume evaluated by structural MRI from baseline to Week 76 will be compared between the treatment group and the placebo group.	from Baseline to Week 24 of treatment
Change in Total White Matter Lesion Volume	The change in total white matter lesion volume evaluated by sturctural MRI from baseline to Week 76 will be compared between the treatment group and the placebo group.	from Baseline to Week 24 of treatment
Change in Cortical Gray Matter Lobar Volumes	The change in cortical gray matter lobar volumes evaluated by sturctural MRI from baseline to Week 76 will be compared between the treatment group and the placebo group.	from Baseline to Week 24 of treatment
Change in Subcortical Nuclei Volumes	The change in subcortical nuclei volumes evaluated by stuctural MRI from baseline to Week 76 will be compared between the treatment group and the placebo group.	from Baseline to Week 24 of treatment
Change in Blood-Based Neurodegeneration Biomarkers	The change in blood-based neurodegeneration biomarkers (includingAmyloid-β (Aβ42/40 ratio), Phosphorylated tau (p-tau217), Glial fibrillary acidic protein (GFAP), and Neurofilament light chain (NfL), etc.）evaluated by Simoa from baseline to Week 76 will be compared between the treatment group and the placebo group.	from Baseline to Week 24 of treatment
Change in Heart Rate Variability	Change in heart rate variability from baseline to Week 24 will be assessed using time-domain and/or frequency-domain heart rate variability analysis	from Baseline to Week 24 of treatment
Change in Cardiovascular Autonomic Reflex Test Result	Change in cardiovascular autonomic reflex function from baseline to Week 24 will be assessed using standardized cardiovascular autonomic reflex testing	from Baseline to Week 24 of treatment
Change in Glycated Haemoglobin (HbA1c) Levels	Change in HbA1c levels from baseline to weeks 24	from Baseline to Week 24 of treatment
Change in fasting insulin	Fasting insulin	from baseline to weeks 24 of treatment

Collaborators and Investigators

• Sponsor: The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School

Study record dates

Study Major Dates

• Study Start (Estimated): May 20, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: May 19, 2026
• First Submitted That Met QC Criteria: June 9, 2026
• First Posted (Actual): June 11, 2026

Study Record Updates

• Last Update Posted (Actual): June 11, 2026
• Last Update Submitted That Met QC Criteria: June 9, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Mild Cognitive Impairment; Cognitive Impairment; Type 2 Diabetes; Transcutaneous Auricular Vagus Nerve Stimulation
• Additional Relevant MeSH Terms: Endocrine System Diseases; Mental Disorders; Metabolic Diseases; Neurocognitive Disorders; Glucose Metabolism Disorders; Diabetes Mellitus; Cognition Disorders; Nutritional and Metabolic Diseases; Cognitive Dysfunction; Diabetes Mellitus, Type 2
• Other Study ID Numbers: 2026-0451-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No