Abstract: Objective: To develop the Self-Care Protection Motivation Scale for patients with type 2 diabetes mellitus and to test its reliability and validity. Methods: Based on the Protection Motivation Theory (PMT), through literature reviews and group discussion, the initial item pool of the scale was constructed. Through 2 rounds of Delphi expert consultation, the initial scale was developed. Through preliminary test, the scale items were further revised. A questionnaire survey was conducted among 275 patients with type 2 diabetes mellitus to test the reliability and validity of the scale. Results: The finalized Self-Care Protection Motivation Scale included 7 dimensions with 38 items. The exploratory factor analysis identified 7 principal factors, which accumulatively explained 63.169% of total variance. The Content Validity Index of the scale was 0.933. Criterion validity r was 0.419 (P<0.001). Cronbach's α coefficient of the scale was 0.893, and cronbach's α coefficients of 7 dimensions ranged from 0.707 to 0.909. Split-half reliability of the scale was 0.744, and split-half reliability of 7 dimensions ranged from 0.666 to 0.896. Conclusion: Self-Care Protection Motivation Scale for patients with type 2 diabetes mellitus has good reliability and validity, which can be used to evaluate type 2 diabetes patients' self-care protection motivation, and to predict the likelihood of patients implementing self-care behavior.

Key words: type 2 diabetes; self-care; protection motivation; scale development; reliability; validity; nursing care