This retrospective study was approved by the Ethics Committee of Beijing Changping District Hospital of Integrated Traditional Chinese and Western Medicine and included clinicians who dealt with type 2 diabetes and all patients with type 2 diabetes who were treated at the study center during the study period. The study inclusion and exclusion criteria are described in Box 1. The stripping and shedding criteria were as follows: adverse events, lack of efficacy, loss of follow-up, automatic withdrawal of subjects, and incomplete data that could affect the efficacy evaluation.
Box 1 Participant inclusion and exclusion criteria
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Participant inclusion criteria
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Participant exclusion criteria
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► Patients with definite diagnosis of type 2 diabetes in HIS system from January 1, 2018 to December 31, 2018,All those with ICD code E11.901 were included.
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►Patients with contraindications to metformin, namely: 1) Moderate (grade 3B) and severe renal failure or insufficiency [Cr < 45mL/min or eGFR < 45mL/min (min 1.73m2)],
2) Diseases that can cause hypoxia (especially acute or chronic disease exacerbation), such as decompensated heart failure, respiratory failure, recent myocardial infarction, shock,
3) Severe infection and trauma, major surgical operations, clinical hypotension, etc.,
4) Those who are known to be allergic to metformin,
5) Acute or chronic metabolic acidosis, including DKA with or without coma (DKA requires insulin treatment),
6) Alcoholics,
7) Patients who have received intravascular injection of iodized contrast agent may temporarily stop using this product,
8) Uncorrected deficiency of vitamin B12 and folic acid.
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► Provision of consent to participate in the survey independently.
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► Patients who are not routinely managed by our hospital, i.e. those who come to our hospital temporarily for medical treatment due to other matters such as tourism,
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► Samples of pregnant women and children under 10 years old,
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► People with difficulty in completing visits and follow-up due to cognitive and communication barriers.
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4. Research methods
4.1. Extraction of the study variables
The following information was extracted from the hospital records
- General information: Patient's name, ID number, sex, age, clinical diagnosis, and date that diabetes was diagnosed.
- Information on metformin use: Whether metformin was used and the dose and prescribing frequency.
- Patient's health status: Blood glucose control, complications, and liver and kidney function.
4.2. Compared the glycemic control of metformin users and non-users and the metformin use and non-use among patients with type 2 diabetes.
4.3. Statement
All methods were performed in accordance with the relevant guidelines and regulations. All participating patients in this study signed the informed consent form and filled out the questionnaire.
5. Questionnaire development
Data from a mixed-methods systematic review was used to investigate the reasons why physicians and patients were not using metformin. The physicians’ questionnaire included four sections: 1. Demographic information, including the participants’ age, sex, number of years qualified, and the specialty, 2. Participants’ description of situations wherein metformin was not used for treating type 2 diabetes. 3. Participants' knowledge of and willingness to understand the latest version of the guidelines and instructions. 4. Participants’ analysis of why they did not receive the latest version of guidelines and instructional knowledge update as well as preferences for how they wished to obtain relevant information. Sections 1 and 3 used closed questions to collect quantitative data. Sections 2 and 4 contained two open-ended questions to allow the participants to answer without restriction. The in-built survey logic ensured that participants were shown pertinent questions based on their previous answers. The patient questionnaire was divided into two parts: demographic information, including age, sex, years since being diagnosed with type 2 diabetes, clinical diagnosis, test value,of liver and kidney function and blood sugar control and subjective factors underlying the reasons for the patients’ failure to use metformin. Prior to the study completion, participants were encouraged to share any additional information that they deemed relevant in order to capture useful insights that were unaddressed elsewhere in the questionnaire. The final versions of the questionnaires can be found in the Online Supplementary File 1 and File 2.
6. Data storage
All electronic data were stored in password-protected computer files that were only accessible to study investigators. Participants who disclosed personal details were additionally protected by coding in data files, and these password-protected files will be retained for 10 years, in conformance with ethical policies.
7. Data analysis
Pareto's law was applied in cause analysis to identify the main, secondary, and general influencing factors. The specific method involved calculating the number and percentage of cause distributions and then sorting them from high to low. A cumulative percentage ≤80% indicated the main reason, which is represented by "A", the secondary reason, with a cumulative percentage of 80%–90% represented by "B", and the general reason with a cumulative percentage >90% represented by "C” [20].
Demographic data was tabulated, and a primary descriptive analysis of the data was performed using IBM SPSS Statistics, V.26.0. Count data was presented as percentages, the measurement data was expressed as average value, and multivariate logistic analysis was used for regression analysis. P < 0.05 was considered statistically significant. Cronbach's coefficient was used to evaluate the internal consistency of the questionnaire. Factor analysis was used to evaluate structure validity.[21].