Objective: Assessing diabetes self care management is essential for nursing care for diabetes.There is a need to have valid and reliable scales that assess the actual performance of diabetes self management,The purpose of this study was to revise and conduct psychometric testing and analysis of the Diabetes Self Management Scale (DSMS).Methods: A cross-sectional methodological design was used.A convenience sample was used and 78 adults with diabetes and taking insulin from five sites in the Midwest area of the U.S participated in the study.Reliability analysis was done using Ferketich techniques to make decisions about whether any given item should be retained or deleted.Results: A descriptive analysis for the 60 items of the scale was conducted;several items had low variability compared to the other items on the scale.The correlation matrices showed that a total of 20 items had poor item characteristics.These 20 items were deleted resulting in developing 40-item version of the scale.The 40-item scale had high level of intal consistency (Cronbach’s α =0.947).The validity testing of the 40-item scale was guided by the Research Model for Diabetes Self Care Management;results were congruent with the model and showed strong correlation with self efficacy,moderate correlation with self care agency,and weak correlation with diabetes knowledge.Conclusion: The items and the scale (DSMS) have undergone careful psychometric testing.The 40-item DSMS is a reliable and valid instrument to measure diabetes self care management among people with diabetes.