Assessing self-efficacy in type 2 diabetes management: validation of the Italian version of the Diabetes Management Self-Efficacy Scale (IT-DMSES)

BACKGROUND: Being highly self-efficacious is a key factor in successful chronic disease self-management. In the context of measuring self-efficacy in type 2 diabetes management, the Diabetes Management Self-Efficacy Scale (DMSES) is the most widely used scale. The aim of this study was to adapt the English version of the scale to Italian and to evaluate the psychometric properties of the Italian version of DMSES in type 2 diabetes (IT-DMSES). METHODS: We conducted a cross-sectional study of people with type 2 diabetes attending the Endocrine-Metabolic Disease Care Unit of the Internal Medicine Department of San Marino State Hospital between October 2016 and February 2017. Patients completed a socio-demographic and clinical data form, the IT-DMSES and 3 self-report questionnaires measuring diabetes distress (PAID-5), psychological well-being (WHO-5) and depression (PHQ-9). Psychometric testing included construct validity (principal component analysis), internal consistency (Cronbach’s α coefficient) and convergent/discriminant validity (Spearman’s correlation coefficient). Decision tree analysis was performed to classify patients into homogeneous subgroups of self-efficacy based on their demographic and clinical characteristics. RESULTS: Participants were 110 males and 55 females, mean age of 65.2 years (SD ± 9), 56.9% had been diagnosed for 1–15 years, 63% had HbA1c level > 53 mmol/mol. Two main factors underlain the construct of self-efficacy in diabetes management: ‘Disease Management’ and “Lifestyles Management”. Disease Management had a good reliability (α = .849) and Lifestyle Management had an excellent reliability (α = .902) indicating that the instrument is internally consistent. A negative and weak correlation was found between Lifestyle management, PAID-5 (r = − 0.258, p = < 0.01) and PHQ-9 (r = − 0.274, p = < 0.01) and a positive one with WHO-5 (r = 0.325, p < 0.01) supporting convergent validity. Disease management was uncorrelated with PAID-5 (r = − 0.142, p = 0.083), PHQ-9 (r = − 0.145, p = 0.076) and weekly correlated with WHO-5 (r = 0.170, p = 0.037) confirming discriminant validity. Higher levels of self-efficacy in lifestyle management were found in patients diagnosed for at least 1 year up to 15 years and aged > 65 years and the poorest self-efficacy was found in males < 65 years. CONCLUSIONS: Results support the validity and reliability of IT-DMSES. The scale can be used in research and clinical practice to monitor type 2 diabetes self-management over time. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12955-018-0901-3) contains supplementary material, which is available to authorized users.