Research Objectives This study aims to investigate the relationship between executive function and diet adherence in patients with type 2 diabetes mellitus (T2DM) from both subjective and objective perspectives and to clarify the effect of executive function intervention of inhibitory control training based on computer on diet adherence.

Research design This study includes three parts. In Part 1, the subjective measurement (questionnaire) and objective measurement (cognitive task performance) are combined to comprehensively explore the relationship between executive function and diet adherence in patients with type 2 diabetes. In the second part, ERP technology is used to investigate the neural mechanism of inhibitory control in type 2 diabetic patients with different diet adherence. Part III is a randomized controlled trial. The control group adopts non-food-related inhibitory control training, and the experimental group adopts food-related inhibitory control training.

Participants The inclusion criteria were as follows: T2DM patients who (1) have met the 1999 WHO diagnostic criteria for diabetes; (2) have a course of disease ≥6 months; (3) have an age ≥18 years old; (4) have good verbal communication and understanding skills; (5) have normal vision or corrected vision, no color blindness or color asthenia; (6) have normal finger function and ability to do key reactions; (7) have a MoCA score ≥25; and (8) have given informed consent and were willing to participate in the study. Patients who (1) have a history of cerebrovascular disease or other central nervous system injury and (2) have difficulty completing the questionnaire or the computer-based cognitive measurement tasks were excluded.

Sampling method and sample size In Part 1, convenience sampling method is used, and the sample size is calculated according to 10-15 times of the research indicators. A total of 23 research indicators were included in the analysis of this study, and at least 230 are needed. Considering the loss rate of 20%, a total of 276 subjects are needed. In the second part, convenience sampling method is also used. According to the literature reviewed, the effect size was 0.93, taking α=0.05, β=0.80, and the sample size was 40 cases calculated by GPower3.1.9.7 software. The sample size is increased by 20% considering the withdrawal of participants and sample loss. Finally, the sample size n1 (number of patients with high diet compliance) =n2 (number of patients with low diet compliance) =50 cases. In Part III, the convenience sampling method is used. The sample size was determined as 60 cases by referring to previous studies. Patients with type 2 diabetes who meet the inclusion criteria are numbered from 1 to 60. Starting from any row or column in the random number table, two digits are read in turn as a random number under the number, and then all the random numbers are sequenced from small to large. This study is a single-blind trial, and only the investigators themselves are aware of the group assignment, and the subjects are unaware of the group assignment.

In Part 1, the Dietary Behavior Adherence Scale for Patients with Type 2 Diabetes Mellitus is used to measure participants' dietary adherence; the Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) is used to subjectively measure participants' executive function; Stop signal task (SST) and Stroop task are used objectively measure participants' executive function. In the second part, ERP technology is used to investigate the neural mechanism of executive function in type 2 diabetic patients with different diet adherence. Part III is a randomized controlled trial. The control group adopts non-food-related inhibitory control training, and the experimental group adopts food-related inhibitory control training. Both training tasks are computer-based, with participants performing a simple keypress response.

Inclusion Criteria:

• Clinical diagnosis of Type 2 Diabetes Mellitus
• Must have a course of disease ≥6 months
• Must have an age ≥18 years old
• Must have good verbal communication and understanding skills
• Must have normal vision or corrected vision, no color blindness or color asthenia
• Must have normal finger function and ability to do key reactions
• Must have a Montreal Cognitive Assessment (MoCA) score ≥25
• Must have given informed consent and were willing to participate in the study.

Exclusion Criteria:

• Have a history of cerebrovascular disease or other central nervous system injury
• Have difficulty completing the questionnaire or the computer-based cognitive measurement tasks