Patients with diabetes mellitus (DM) are always required to be able to control a healthy lifestyle throughout their life to avoid various diseases that can accompany the previous illness. However, psychological factors in the form of despair due to lack of hope make people with diabetes more depressed and less able to control behavior and maintain blood sugar stability, so an excellent internal locus of control is needed to be stronger. This study aimed to determine the effect of hope therapy in reducing hopelessness and increasing internal locus of control in people with DM. The research design used a experimental study with ten randomly selected respondents divided into two groups, namely the control group and the experimental group. Data retrieval using the locus of control scale and the beck hopelessness scale. Data analysis used non-parametric analysis, namely the Mann Whitney test, Wilcoxon test, and Spearman’s Rank Correlation test. The results of the Mann-Whitney U test on the internal locus of control variable show a value of 0.000 and a p score of 0.008 (p <0.05), it can be concluded that there are differences in the internal locus of control in the experimental group compared to the internal locus of control in the control group. The hopelessness variable shows a value of 0.000 and a p score of 0.008 (p <0.05), this indicates that there is a difference in hopelessness in the experimental group and the control group. There is a decrease in hopelessness and an increase in internal locus of control in people with DM given hope therapy.