This study explores the effect of an individualized dietary intervention program based on COM-B theory on improving health outcomes in patients with T2DM, improvement in metabolic health indicators and an increased diabetes remission rate, as well as changes in dietary adherence, self-management ability, and self-efficacy.
This study explores the effect of an individualized dietary intervention program based on the Capability, Opportunity, Motivation-Behavior (COM-B) theory on improving health outcomes in patients with type 2 diabetes mellitus (T2DM), including glycemic control, improvement in metabolic health indicators. The control group will implement a standardized diabetes management, including health guidance, WeChat group management, and supervision and management via a metabolic management center(MMC) mini-program. On the basis of the control group, the intervention group will implement a dietary intervention model based on the COM-B theory model and a TDF framework, including ① psychological capability education: intensified education on diabetes knowledge; ② physical capability education: intensified training in practical skills; ③ motivation management: action planning, behavior goal setting, reward mechanisms, and establishing role models; ④ support and supervision: empowerment management via a WeChat group, social support, problem solving, and guidance based on indicator monitoring on the clinician side of a health diet APP. We will observe dietary-related glycemic control, improvement in metabolic health indicators, as well as changes in dietary adherence, self-management ability, and self-efficacy.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
30
Intensified education on diabetes knowledge
Intensified training in practical skills for dietary management
action planning, behavior goal setting, problem solving, reward mechanisms, and establishing role models
Beijing Luhe Hospital, Capital Medical University
Beijing, China
HbA1c
HbA1c will be measured using High-Performance Liquid Chromatography (HPLC), the internationally recognized reference method for HbA1c quantification. Venous blood samples will be collected in EDTA-anticoagulated tubes and analyzed by ion-exchange HPLC, which separates hemoglobin fractions based on their interaction with a chromatography column. Results will be reported as a percentage (%) per NGSP/DCCT standards, with parallel reporting in mmol/mol per IFCC standards. All analyses will be performed in a certified laboratory participating in external quality assessment (EQA) programs to ensure inter-laboratory comparability and result accuracy.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
FBG (Fasting Blood Glucose)
Fasting Blood Glucose (FBG) was measured after an overnight fast of at least 8 hours. Venous blood samples were collected and analyzed using a standardized enzymatic method in a certified clinical laboratory. FBG values were reported in mg/dL. Fasting was defined as no caloric intake except water during the fasting period. The measure reflects baseline glucose levels and was used to assess glycemic status according to established clinical criteria.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
TG (Triglycerides)
Serum total cholesterol was measured to assess overall lipid metabolism status. After an overnight fast of at least 8 hours, venous blood samples were collected and serum total cholesterol concentration was determined using an enzymatic colorimetric method (cholesterol oxidase-peroxidase, CHOD-PAP). Results are reported in mmol/L (conversion: 1 mmol/L = 38.67 mg/dL). According to the Chinese Guidelines for the Prevention and Treatment of Dyslipidemia in Adults (2016 revision), desirable TC is \<5.18 mmol/L, borderline high is 5.18-6.19 mmol/L, and elevated TC is ≥6.22 mmol/L. Lower values indicate improved lipid control.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
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empowerment management via a WeChat group, social support, and guidance based on indicator monitoring on the clinician side of a mini-program
a routine dietary management model will be implemented, including health guidance, WeChat group management, and supervision and management
TC (Total Cholesterol)
Serum total cholesterol was measured to assess overall lipid metabolism status. After an overnight fast of at least 8 hours, venous blood samples were collected and serum total cholesterol concentration was determined using an enzymatic colorimetric method (cholesterol oxidase-peroxidase, CHOD-PAP). Results are reported in mmol/L (conversion: 1 mmol/L = 38.67 mg/dL). According to the Chinese Guidelines for the Prevention and Treatment of Dyslipidemia in Adults (2016 revision), desirable TC is \<5.18 mmol/L, borderline high is 5.18-6.19 mmol/L, and elevated TC is ≥6.22 mmol/L. Lower values indicate improved lipid control.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
DKT (Diabetes Knowledge Test)
Diabetes knowledge assessed using the Chinese version of the Diabetes Knowledge Test (DKT) scale, originally developed by Fitzgerald et al. and culturally adapted and validated by Sun et al. The scale consists of 23 questions, each worth 1 point. Total score ranges from 0 to 23, with higher scores indicating better diabetes knowledge. The scale demonstrates acceptable internal consistency (Cronbach's α = 0.76).
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
DSES (Diabetes Self-Efficacy Scale)
Self-efficacy assessed using the Diabetes Self-Efficacy Scale (DSES) developed by Lorig et al. and validated by Sun et al. The scale consists of 8 items, each rated on a scale from 1 to 10. Total score ranges from 8 to 80, with higher scores indicating stronger self-efficacy in diabetes self-management. The scale demonstrates excellent internal consistency (Cronbach's α = 0.889).
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
SDSCA (Summary of Diabetes Self-Care Activities)
The Summary of Diabetes Self-Care Activities (SDSCA) scale will be used to evaluate patients' diabetes self-management behaviours. Originally developed by Toobert et al., the SDSCA has been translated into Chinese and validated for the Chinese population by Sun et al. The scale assesses patients' self-care performance over the preceding 7 days across five behavioural domains: general diet, specific diet, physical activity, blood glucose self-monitoring, and foot care. It comprises 11 items, each scored on a scale of 0 to 7, where 0 indicates that the behaviour was not performed on any day and 7 indicates performance on every day of the week. Total scores are calculated as the mean of all item scores, with higher scores reflecting better self-management. The Chinese version of the SDSCA has demonstrated good internal consistency, with a Cronbach's α of 0.84.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Insulin Resistance Index
Insulin resistance was evaluated using the Homeostasis Model As-sessment of Insulin Resistance (HOMA-IR). HOMA-IR was calculated using the formula: HOMA-IR = \[FPG (mmol/L) × FINS (μU/mL)\] / 22.5. Higher HOMA-IR values indicate greater insulin resistance.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Insulin Sensitivity Index
Insulin sensitivity was evaluated using the Matsuda Insulin Sensitivity Index (ISI-Matsuda), a composite measure derived from a standard 75-g oral glucose tolerance test (OGTT). Higher ISI-Matsuda values indicate greater insulin sensitivity.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Insulin C-peptide test
C-peptide levels were determined using an electrochemiluminescence immunoassay (ECLIA) method. Results are reported in ng/mL and reference range is 0.78-1.89 ng/mL
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Oral Glucose Tolerance Test
Glucose tolerance was assessed using a standard 75-g oral glucose tolerance test (OGTT) performed according to the World Health Organization (WHO) protocol. After an overnight fast of at least 8-10 hours, a fasting venous blood sample was collected for baseline plasma glucose measurement. Participants then ingested a solution containing 75 g anhydrous glucose dissolved in 250-300 mL water within 5 minutes. Subsequent venous blood samples were collected at 30, 60, 90, and 120 minutes post-ingestion for plasma glucose measurement using the glucose oxidase or hexokinase enzymatic method. The primary outcome parameter is the 2-hour postload plasma glucose (2h-PG, mmol/L). Glucose tolerance status was classified according to WHO/ADA criteria: normal glucose tolerance (NGT): FPG \<6.1 mmol/L and 2h-PG \<7.8 mmol/L; impaired fasting glucose (IFG): FPG 6.1-6.9 mmol/L and 2h-PG \<7.8 mmol/L; impaired glucose tolerance (IGT): FPG \<7.0 mmol/L and 2h-PG 7.8-11.0 mmol/L; diabetes mellitus (DM): FPG ≥
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
High-Density Lipoprotein Cholesterol (HDL-C)
Serum high-density lipoprotein cholesterol was measured to assess reverse cholesterol transport capacity and cardiovascular protective status. After an overnight fast of at least 8 hours, venous blood samples were collected and serum HDL-C concentration was determined using a direct homogeneous enzymatic method (direct HDL assay). Results are reported in mmol/L (conversion: 1 mmol/L = 38.67 mg/dL). Unlike TC, TG, and LDL-C, higher HDL-C values are considered protective against cardiovascular disease. According to the Chinese Guidelines for the Prevention and Treatment of Dyslipidemia in Adults (2016 revision), desirable HDL-C is ≥1.04 mmol/L and reduced HDL-C is \<1.04 mmol/L.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Low-Density Lipoprotein Cholesterol (LDL-C)
Serum low-density lipoprotein cholesterol was measured as the primary indicator of atherogenic lipid burden. After an overnight fast of at least 8 hours, venous blood samples were collected and serum LDL-C concentration was determined using a direct homogeneous enzymatic method (direct LDL assay). Where the direct assay was not available, LDL-C was calculated using the Friedewald equation: LDL-C = TC - HDL-C - TG/2.2 (all values in mmol/L), applicable only when TG \<4.52 mmol/L. Results are reported in mmol/L (conversion: 1 mmol/L = 38.67 mg/dL). According to the Chinese Guidelines for the Prevention and Treatment of Dyslipidemia in Adults (2016 revision), desirable LDL-C is \<3.37 mmol/L, borderline high is 3.37-4.12 mmol/L, and elevated LDL-C is ≥4.14 mmol/L. Target LDL-C levels were individualized according to each participant's cardiovascular risk stratification.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Weight
Body composition was measured using a multi-frequency bioelectrical impedance analyzer (InBody 770, InBody Co., Ltd., Seoul, South Ko-rea). Participants fasted for ≥2 hours, avoided strenuous exercise for 24 hours, removed shoes and metal accessories, emptied their blad-ders, and stood upright for 5 minutes before testing to stabilize fluid distribution. During measurement, participants grasped hand elec-trodes with arms abducted \~30° from the body and remained still. Measured parameters included weight (kg), height (cm), BMI (kg/m²), body fat percentage (%), visceral fat area (cm²), and total body water (L). All assessments were performed at the same time of day (±2 hours) across visits.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Height
Body composition was measured using a multi-frequency bioelectrical impedance analyzer (InBody 770, InBody Co., Ltd., Seoul, South Ko-rea). Participants fasted for ≥2 hours, avoided strenuous exercise for 24 hours, removed shoes and metal accessories, emptied their blad-ders, and stood upright for 5 minutes before testing to stabilize fluid distribution. During measurement, participants grasped hand elec-trodes with arms abducted \~30° from the body and remained still. Measured parameters included weight (kg), height (cm), BMI (kg/m²), body fat percentage (%), visceral fat area (cm²), and total body water (L). All assessments were performed at the same time of day (±2 hours) across visits.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
BMI
Body composition was measured using a multi-frequency bioelectrical impedance analyzer (InBody 770, InBody Co., Ltd., Seoul, South Ko-rea). Participants fasted for ≥2 hours, avoided strenuous exercise for 24 hours, removed shoes and metal accessories, emptied their blad-ders, and stood upright for 5 minutes before testing to stabilize fluid distribution. During measurement, participants grasped hand elec-trodes with arms abducted \~30° from the body and remained still. Measured parameters included weight (kg), height (cm), BMI (kg/m²), body fat percentage (%), visceral fat area (cm²), and total body water (L). All assessments were performed at the same time of day (±2 hours) across visits.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Body fat percentage
Body composition was measured using a multi-frequency bioelectrical impedance analyzer (InBody 770, InBody Co., Ltd., Seoul, South Ko-rea). Participants fasted for ≥2 hours, avoided strenuous exercise for 24 hours, removed shoes and metal accessories, emptied their blad-ders, and stood upright for 5 minutes before testing to stabilize fluid distribution. During measurement, participants grasped hand elec-trodes with arms abducted \~30° from the body and remained still. Measured parameters included weight (kg), height (cm), BMI (kg/m²), body fat percentage (%), visceral fat area (cm²), and total body water (L). All assessments were performed at the same time of day (±2 hours) across visits.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Visceral fat area
Body composition was measured using a multi-frequency bioelectrical impedance analyzer (InBody 770, InBody Co., Ltd., Seoul, South Ko-rea). Participants fasted for ≥2 hours, avoided strenuous exercise for 24 hours, removed shoes and metal accessories, emptied their blad-ders, and stood upright for 5 minutes before testing to stabilize fluid distribution. During measurement, participants grasped hand elec-trodes with arms abducted \~30° from the body and remained still. Measured parameters included weight (kg), height (cm), BMI (kg/m²), body fat percentage (%), visceral fat area (cm²), and total body water (L). All assessments were performed at the same time of day (±2 hours) across visits.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Waist Circumference (WC)
A non-elastic flexible tape at the midpoint between the lowest rib margin and the iliac crest at the end of normal expiration, with the participant standing and arms relaxed at sides. Measurements were taken twice and averaged. Results are reported in cm.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Hip Circumference (HC)
A non-elastic flexible tape at the level of the greatest posterior protru-sion of the buttocks, with the participant standing with feet together. Measurements were taken twice and averaged. Results are reported in cm.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Waist-hip ratio (WHR)
WHR is calculated as the waist circumference divided by the hip cir-cumference.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Dietary behaviour diary
Trained investigators assisted with app installation and provided standardized usage instructions at enrollment. Participants photo-graphed and logged all meals and beverages daily, and the app au-tomatically calculated total caloric intake (kcal/day) and macronutri-ent composition (carbohydrate, protein, and fat in g/day and % of to-tal energy) based on a built-in Chinese food composition database.
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
Dietary adherence
Dietary adherence assessed using the Dietary Behaviour Compliance Scale developed by Zhao et al. The scale comprises 5 dimensions with 23 total items: fruits and vegetables (5 items), oil and salt (4 items), carbohydrates and fat (5 items), cooking and dining habits (4 items), and overall dietary self-regulation (5 items). Each item is rated on a 5-point Likert scale where 1 = "never" and 5 = "always". Total score ranges from 23 to 115, with higher scores indicating better adherence to recommended dietary behaviours. The scale demonstrates excellent internal consistency (Cronbach's α = 0.886).
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks
International Physical Activity Questionnaire-Short Form (IPAQ-SF)
Physical activity assessed using the IPAQ-SF. Participants recall and report frequency (days/week) and duration (minutes/day) of physical activity, plus total daily sitting time on weekdays, over the previous 7 days. Metabolic equivalent (MET) values are: 3.3 METs for walking, 4.0 METs for moderate-intensity activity, and 8.0 METs for vigorous-intensity activity. Weekly physical activity for each intensity is calculated as: MET-min/week = MET value × frequency (days/week) × duration (min/day). The questionnaire demonstrates good validity; correlations between weekly activity time across IPAQ-SF dimensions and pedometer-recorded total weekly step counts ranged from 0.417 to 0.440 (p \< 0.05).
Time frame: before the intervention and from enrollment to the end of treatment at 12 and 24 weeks