Background: The current level of insulin knowledge, attitudes, and practices of patients self-administering their first insulin injection needs to be improved. There is an emerging need to develop a program for patients self-administering their first insulin injection based on the e-coach model derived from the temporal self-regulation theory. Objective: This study aimed to examine the effectiveness of a temporal self-regulation theory–based e-coach program on the knowledge, attitude, and practice of patients self-administering their first insulin injection. Methods: A quasi-experimental research design was used, and the study adhered to the Transparent Reporting of Evaluations with Nonrandomized Designs statement. The study was developed and evaluated in a level IIIA hospital between May 1 and December 1, 2022, in Suzhou, Jiangsu Province, China. The control group received care as usual. The intervention group received a self-regulation program called the e-coach program: the “COACHING” implementation steps. The insulin attitude scores and insulin knowledge-practice scores were compared using repeated-measures ANOVA. In particular, given that baseline blood glucose monitoring frequency differed significantly between the 2 groups, thereby compromising their comparability, a repeated-measures analysis of covariance (ANCOVA) was performed, with monitoring frequency entered as a covariate. This approach was adopted to enhance the scientific rigor of the findings and reduce potential bias. Results: In total, 86 patients were enrolled; of these, 75 patients were followed up, 40 in the experimental group and 35 in the control group. Repeated-measures ANOVA results revealed statistically significant between-group effects (=47.67, <.001), time effects (=5.02, =.02), and interaction effects (=4.75, =.03) for total insulin knowledge scores in both groups. In both groups, statistically significant between-group effects (=16.04, <.001) and interaction effects (=12.52, <.001) were observed for total insulin attitude scores, but time effects (=2.47, =.11) were not statistically significant. In both groups, statistically significant between-group effects (=0.66, =.004) were observed for total insulin practice scores, but time effects (=1.05, =.35) and interaction effects (=2.82, =.08) were not statistically significant. Conclusions: The e-coach program based on the TST was effective in improving insulin knowledge and insulin attitude but was not proven effective for insulin practice. A longer follow-up study is needed to uncover its long-term benefits on clinical outcomes. Trial Registration: Chinese Clinical Trial Registry ChiCTR2200058895; https://tinyurl.com/mtztdvc4
