Le-Diabet is an Android mobile application developed for diabetes management whose effectiveness has remained unknown. This research aimed to investigate its impact on self-efficacy and blood glucose levels in patients with diabetes. Employing a quasi-experimental approach, the study utilized a pretest and posttest control group design. The sample included 28 respondents in the control group and 34 in the intervention group, selected through purposive sampling based on criteria such as diagnosed diabetes, smartphone usage, and 6 weeks of using the Le-Diabet application. Self-efficacy was measured using the Diabetes Management Self-Efficacy Scale, while blood glucose levels were monitored with a glucometer. Data analysis involved paired and unpaired t-tests. The results revealed a significant increase in self-efficacy scores by 3.1 points [p=0.000, 95% confidence interval (CI) = -6.006 to -1.876] in the intervention group, whereas the control group experienced a decrease of 1.9 points. Both groups exhibited an increase in blood glucose levels, with a significant rise of 35.6 mg/dL (p=0.035, 95% CI = -68.578 to -2.636) in the control group and a non-significant increase of 3.59 mg/dL (p=0.076, 95% CI = -22.759 to 15.582) in the intervention group. The research concludes that the use of the Le-Diabet application enhances self-efficacy and maintains blood glucose level stability; however, it has not shown an impact on metabolic syndrome indicators in diabetic patients. Further research is needed, utilizing a larger and more diverse sample from various age groups and extending the duration of the study to evaluate the long-term impact of the applied intervention.