One of the successes in managing diabetes care is compliance in taking medication. Apart from that, you must have high ability and self-confidence or what is usually called self-efficacy in carrying out good diabetes management. This study aims to determine the relationship between self-efficacy and medication adherence in diabetes sufferers. This research uses a cross sectional approach. The sampling technique used in this research used purposive sampling with a sample size of 52 people with diabetes who received outpatient treatment at RSI Mabarrot MWC NU Bungah in January-February 2024. The instrument used in this research was the Diabetes Management Self Efficacy Scale questionnaire (DMSES-UK) and Morisky Medication Adherences (MMAS-8). Data analysis used the Spearman rank correlation statistical test. The results showed that of the 52 people, 44 people had high self-efficacy, with 38 people (73.1%) having high medication adherence, and 2 (3.8%) people having moderate medication adherence. The results of data analysis show a significance value of 0.000 <0.05 with a correlation coefficient value of 0.552, meaning that there is a strong relationship between self-efficacy and adherence to taking medication in diabetes mellitus sufferers. High self-efficacy will increase adherence to taking medication in diabetes sufferers, because they have a high sense of confidence in managing diabetes care.