All participants will be invited to attend the baseline visit and five further study appointments for 12 months on post-randomization. Data at every visit will be collected in case report forms (CRFs) by the trial team. All data will be entered into a secure database by research assistants (i.e., data collectors). In the current trial and further ancillary studies, there are no plans for collection, laboratory evaluation, and storage of biological specimens for genetic or molecular analysis.

After signing an informed consent, participants will be interviewed using a standard questionnaire to obtain information on demographic characteristics (including sex, date of birth, race, education, occupation, annual income, residence, family history and diabetic duration), lifestyle risk factors (physical activity, smoking status and alcohol consumption), history of past and present illness, and current medications. Blood pressure, height, weight and waist circumference will be measured with the use of standard methods. Fasting blood samples and urine sample will be collected to test blood routine, liver and renal function, eGFR, glucose, lipid, serum creatase, glycated hemoglobin (HbA1c), urine routine, and urinary albumin to creatinine ratio. Ankle brachial index (ABI) will also be measured using a pulse waveform analyzer BP-203RPE II (form PWV/ABI, Omron Healthcare Co., Kyoto, Japan).

Based on the above-mentioned information, eligible participants will be defined by an on-site investigator and then randomized to the study group or control group by an independent offsite investigator. Subsequently, every randomized participant will continue to perform plantar pressure tests by the trained podiatrist. Footscan® Pressure Measurement System (RSscan international NV, Paal, Blegium) will be used to obtain the data of plantar pressure. Before plantar pressures are measured, each participant will undertake at least two practice walks along the plate walkway to familiarize them with the experimental process. Then, each participant will be asked to walk in bare feet upon the footscan platform at self-selected gait speed for at least three successful trials. The foot data including peak plantar pressure will be recorded by the Footscan® pressure measure system, which automatically divided the foot into 10 masked regions: hallux, toes 2–5, first to fifth metatarsals, midfoot, medial heel, and lateral heel. Locations of previous ulceration, foot deformity or preulcerative signs will be the primary sites of interest. In additional, blood flow parameters of lower extremities, which include maximum systolic velocity, maximum diastolic velocity, and time-averaged mean velocity, will also be assessed by a vascular ultrasound specialist in the vascular ultrasound room of our hospital that is a quiet temperature-controlled environment. Measures will be performed at the same time of day for individual subjects.

Participants will be followed at 1 month (visit 2), 3 months (visit 3), 6 months (visit 4), 9 months (visit 5), and 12 months (visit 6) after randomization. At each visit, the trial team will collect the information including incidence of foot ulcer, footwear adherence, cardiovascular events, glucose profile, and other cardiovascular risk factors control. For physical activity evaluation, participants will be asked to wear a pedometer (P084, SPORTWAY, ShenZhen, China) every day to record the date and steps taken per day. Meanwhile, a concealed activity monitor (Lifecorder Plus, Suzuken) will be attached to the diabetic therapeutic footwear. Activity data will be uploaded by a research assistant to a centralized server via internet at each follow-up visit. Adherence to treatment will be evaluated through the comparison of the step counts recorded by a concealed activity monitor with those recorded by a pedometer. Adherence to treatment will be monitored until the end of follow-up. Plantar pressure distribution patterns will be measured after randomization every 3 months. At the end of follow-up, ABI and blood flow parameters of lower extremities will also be collected. At each visit, if participants make a withdrawal request or are not eligible to continue due to the presence of severe concomitant diseases or conditions listed in the exclusion criteria, they will be discontinued from the study. For participants who drop out, the information including incidence of foot ulcer, footwear adherence, cardiovascular events, ABI (if possible), plantar pressures (if possible), and biochemical parameters (if possible) will be collected.

To improve participant retention and complete follow-up, the following measures will be adopted: participants’ contact information as well as contact information for at least two persons who would know the participants’ whereabouts and could get messages to them will be collected from the patients; a certain amount of subsidies (e.g., RMB 200) will be given to compensate participants for transportation and other costs at every follow-up visit; participants will receive phone appointment 1 day before every follow-up visit. If a participant could not be reached, a research assistant will make other appointments for the participant at least three times on different days, in an effort to schedule the site visit; a social networking platform (e.g., WeChat) will be used to connect with participants and then help investigators know participants’ condition in time, which will contribute to improve participants’ adherence and reduce lost to-follow-up.