Genetics is the basic functional unit of inheritance or heredity that cannot be avoided. Diseases caused by genetics have a percentage of 5-15%, one of which is diabetes mellitus. Based on 2017 data, diabetes is the 3rd largest cause of death in Indonesia and in 2018 Mojokerto was in second place for the East Java region. This study aims to prove the relationship between genetic factors and blood sugar levels in patients with diabetes mellitus at UPT Kedundung, Mojokerto City. The design used in this study is correlation analytic with aapproach cross-sectional with a sample of 60 people selected using accidental sampling technique. Data was collected through interviews, observation of patient medical records, and checking blood sugar levels using GDA. The results of the study using the results spearman rho test showed the value of value (0.000) < (0.05), so there was a strong relationship between genetic factors and blood sugar levels, which means that the more genetic factors there are, the more at risk of experiencing high blood sugar levels. Therefore, preventive measures by maintaining a good lifestyle include eating healthy foods and reducing foods that are high in calories, high in sugar and applying the type, amount, and schedule of maintaining body weight within ideal limits and doing physical activity (exercise) and doing physical activity. control to determine blood sugar levels.