Study design and setting
This multicentre cross-sectional study was conducted in five tertiary grade-A hospitals in Chongqing, China. Individuals with T2DM were invited to take part in this study if they: (1) met WHO diagnostic criteria for T2DM; (2) had age≥18 years; (3) had educational attainment of primary school or above; (4) informed consent. We excluded medical personnel who were T2DM with pregnancy, malignant tumors, history of mental illness and family history, and other serious medical conditions that make it difficult to talk and fill out questionnaires. The sample size was estimated according to the equation n = [m (10-15)] (1 + 20%), where m is the number of independent variables to be included in the planned linear regression[26,27]. There were 13 independent variables in this study, so the calculated sample size is at least 156.
Data collection
The data were collected by convenience sampling between 1 January and 31 December 2019. Five investigators had been given uniform guidance and training before the survey. Then, eligible individuals were invited to participate in this study and were informed of the study's purpose and procedures. Individuals who agreed to participate signed a consent form. Subsequently, the investigators used unified guidance statements to guide the individuals to fill out the questionnaire by themselves. Questionnaires were administered and collected on the spot and every questionnaire was checked item by item in the collecting process to ensure the authenticity and integrity of the data.
Measures
EuroQol Five-Dimensions (EQ-5D)
EQ-5D, developed by EuroQol Group, was used to measure HRQoL[28]. EQ-5D was simple to use and had good reliability and validity, and it has been widely used in health technology assessment [29,30]. EQ-5D included the health status description system and Visual analogue scale(VAS). The health status description system consisted of 5 subscales: pain/discomfort, anxiety/depression, mobility, usual activities, and self-care. The health status description system could not directly calculate the health effect value, Chinese studies adopted the time trade-off method and established the three-level EuroQol Five-Dimensions(EQ-5D-3L) utility value integral system based on the Chinese population for the first time to obtain the health effect value for a total of 243 unique health status of the population[31,32], which contained 3 levels (i.e., 1 = no problems, 2 = some/ moderate problems, and 3 = extreme problems) for each dimension. It provides utility values on which 0.0 corresponds to death, and 1.0 corresponds to full health. The EQ-VAS was a 20cm vertical visual scale used to evaluate the overall health status of the self-feeling of individuals. The top score of 100 represents the best health status in individuals' minds, and the bottom score of 0 represents the worst health status.
Fear of Progression Questionnaire-Short Form(FOP-Q-SF)
FOP-Q-SF, adapted by Mehnert et al. [33] based on the Fear of Progression Questionnaire (FOP-Q) [34], was used to measure FOP. It is a single-dimensional scale with 12 items. All items were rated using a 5-point Likert scale ranging from never (one point) to very often (five points), with higher scores indicating a higher level of FOP. Individuals will suffer from psychological dysfunction if the FoP-Q-SF score is≥ 34 points. The Cronbach's α coefficient of the scale was 0.82, and the scale had a high correlation with FOP-Q (r=0.92), showing good reliability and validity[35].
Hypoglycemia Fear survey II (HFSII)
HFSII, the revised version of HFS, was used to measure FOH based on the experience of diabetic individuals in the last 6 months [36]. It was measured using the 33-item instrument and was divided into a behavior subscale (HFSII-BS) and a worry subscale (HFSII-WS). Every item was rated by a 5-point Likert scale ranging from 0 point to 4 points. Item scores were aggregated to a total score for FOH ranging from 0 to 132, with a higher score indicating a higher level of FOH[31]. This scale has good reliability and validity and has been widely used in individuals with T2DM [37,38].
Diabetes management self-efficacy scale (DMSES)
DMSES was developed in 1999 by Bij1 et al. [39] to assess the self-efficacy of diabetic individuals. Then, it was cross-cultural adapted into the Chinese version by Shu et al.[40]. The Chinese version of DMSES has 20 items and has been divided into four subscales (medication, blood glucose monitoring, diet, and exercise). Every item was rated by an 11-point Likert scale ranging from 0 point to 10 points. The total score of the Chinese version of DMSES ranges from 0 to 200 points, with higher scores indicating a higher level of diabetes management self-efficacy. Its score index is equal to the actual score of the scale divided by the highest possible score of the scale multiplied by 100%, and the score is divided into three levels: high (≥80%), medium (40%-80%), and low (≤ 40%).
Socio-demographic and Clinical Characteristics, such as age, gender, marital status, and educational attainment, were collected using a socio-demographic and clinical data sheet. Diabetes-related complications consisted of diabetic cardiovascular events, diabetic brain lesions, diabetic nephropathy, diabetic peripheral neuropathy, diabetic foot, and diabetic retinopathy. Comorbid conditions were composed of hypertension and hyperlipidemia.
Data analyses
This study used SPSS version 25.0 (IBM Corporation) for data analysis. Descriptive statistics were used to express the participants' characteristics and study variables. Continuous variables conforming to the normal distribution were expressed as mean [Standard Deviation (SD)], otherwise, median [inter-quartile range (IQR)] was used. Categorical variables were expressed using frequencies and percentages. The t-test, one-way analysis of variance (ANOVA), or correlation test were used to contrast the differences or correlations in the HRQoL of participants with different demographics, FOP, FOH, and self-efficacy. If variables were identified as significant (P < 0.05) in these initial tests, those variables were entered into a multiple linear regression analysis with the stepwise method to analyze the associated factors of HRQoL.Bilateral P < 0.05 indicated statistical significance.
Ethical considerations
The research conforms to the provisions of the Declaration of Helsinki in 1995 (as revised in Brazil in 2013). Ethical approval was obtained from Chongqing Medical University Ethical Committee. Informed consent was obtained from individuals with T2DM.