Background Breast cancer is the woman’s leading cause of death in the world to date (DeSantis et al, 2016). Type 2 diabetes mellitus has been recognized as a risk factor for several types of cancer, including breast, liver and pancreatic cancer. Insulin resistance and high insulin levels in type 2 DM are mitogenic for breast cancer cells. Insulin receptors are also often expressed in breast cancer (Yerrabothala et al, 2014). Therefore, the author is interested to discover how the characteristics of breast cancer patients accompanied by type 2 diabetes in H. Adam Malik Medan General Hospital. Methods This study is a descriptive study with a cross sectional design, with a sample of 318 breast cancer patients associated with type 2 diabetes at H. Adam Malik Medan General Hospital from January 2013 to December 2017 who met the inclusion and exclusion criteria. Data taken from medical records. Data that has been collected, processed, and presented descriptively in the form of tables or diagrams using the SPSS program ver. 22. Results In this study 318 breast cancer patients accompanied by type 2 DM were found from a total of 3137 breast cancer patients in H. Adam Malik Medan General Hospital (proportion: 10.13%). The majority of patients were aged 46–55 years old by 121 (38.1%) patients, menarch at the age of 12 as many as 136 (42.8%) patients, 247 (77.7%) patients had menopause, had BMI 23.0 –24.9 kg/m2 as many as 88 (27.7%) patients, had two children by 155 (48.7%) patients, did not have a family history of breast cancer as many as 264 (83%) patients, almost 90% of patients had underwent surgery, had histopathological type of Invasive Ductal Carcinoma (IDC) as many as 231 (72.6%) patients, had grade III tumor by 182 (57.2%) patients, stage III and IV by 110 (69, 2%) patients each, and had TNBC subtypes of 179 (56.3%) patients. Conclusion The majority of breast cancer patients accompanied by type 2 DM were aged 46–55 years old, menarch at the age of 12, 247 (77.7%) patients had menopause, had BMI 23.0 –24.9 kg/m2, had two children, did not have a family history of breast cancer, had underwent surgery, had histopathological type of Invasive Ductal Carcinoma (IDC), had grade III tumor, stage III and IV, and had TNBC subtypes.