Background: Breast cancer had the highest prevalence globally in 2020, with 2.3 million new cases and 685,000 deaths. Approximately 80% of breast cancer cases are first diagnosed at an advanced stage (stages 3 and 4), with 5-10% of these cases experiencing metastasis. Diabetes mellitus (DM) is one of the risk factors and prognostic factors for breast cancer. It is estimated that 10-20% of breast cancer patients also suffer from diabetes mellitus. Patients with diabetes mellitus have about a 20% higher incidence of breast cancer compared to those without diabetes. Therefore, this study was conducted to examine the relationship between type 2 diabetes mellitus as a risk factor for metastatic breast cancer. Methods: This study used an analytic observational method with a cross-sectional approach. The research subjects were breast cancer patients treated at Dr. Moewardi Hospital in 2023, with data obtained from medical records. The sampling technique was purposive sampling. The data were processed and analyzed using bivariate analysis with the chi-square test. Results: There were 60 research subjects, all of whom were female. The majority were aged 40-60 years (56.67%), with an average age of 55.6 years. Of the total subjects, 18 patients (30%) were diagnosed with type 2 diabetes mellitus, while 42 patients (70%) did not have type 2 diabetes mellitus. A total of 26 patients (43.3%) had metastasis, while 34 patients (56.67%) did not. The chi-square test yielded a p-value of 0.069. Conclusions: This study found no significant relationship between type 2 diabetes mellitus and incident of metastatic breast cancer.