Assessment of the psychometric properties of the Persian version of the diabetes self-management questionnaire (DSMQ) in patients with type 2 diabetes

Background Performing self-care behaviors by diabetic patients is essential to achieve optimal glycemic control, reduction of complications, and improvement in the quality of life. The Diabetes Self-care Questionnaire (DSMQ) is designed to assess self-care behaviors that can predict glycemic control. The present study aimed to evaluate the psychometric properties of the Persian version of the DSMQ in patients with type 2 diabetes. Methods The present methodological cross-sectional study investigated 460 patients with T2DM referred to the Isfahan Endocrine and Metabolism Research Center, Isfahan, Iran through the convenience sampling procedure. The translation process of the DSMQ was carried out based on the guidelines suggested by Beaton et al. We assessed the reliability (internal consistency), content validity, convergent validity and construct validity. Construct validity was evaluated using exploratory factor analysis (calibration sample = 230) and confirmatory factor analysis (validation sample = 230). Furthermore, a linear regression analysis was used to determine the prediction power of self-care behaviors in explaining the variance of the HbA1c level. Results In the EFA with Varimax rotation, we extracted four factors that could explain 67.46% of the total variance of the DSMQ scale. The CFA exhibited a satisfactory fit level for the four-factor structure extracted from EFA with the following measures. CFI: 0.980, IFI: 0.980, NFI: 0.956, TLI: 0.974, RMSEA: 0.042). Internal consistency was good (Cronbach's alpha coefficient for the whole scale: 0.84; the subscales: 0.75-0.91). The convergent validity showed significant negative correlations (GM: -0.53; DC: -0.22; PA: -0.16; HU: -0.17; SS: -0.45; p < 0.01) between DSMQ subscales and HbA1c. However, only two factors of glucose management and diet control in the statistical model obtained from regression analysis (stepwise) were able to explain 30% of the HbA1c level (P < 0.001). Conclusion The Persian version of the DSMQ is a valid and reliable instrument to assess self-care behaviors associated with glycemic control in Iranian patients with T2DM. Therefore, this instrument can be used in both future research and clinical practices.