Previous studies have reported that diabetes shortens the survival time of breast cancer patients. Shorter survival time has also been associated with obesity, insulin resistance and high cholesterol. There is some evidence that cameos, a long-acting insulin, promotes the development of breast cancer in some diabetic patients. On the other hand, metformin, which is widely used to treat type 2 diabetes, reduces the risk of breast cancer recurrence. A new Taiwanese study now reports that patients with diabetes reduce the survival rate of early breast cancer patients. The study aimed to investigate the impact of diabetes on survival in patients diagnosed with breast cancer. To conduct this study, the authors analyzed data from women diagnosed with early-stage breast cancer between 2003 and 2004 in the Taiwan Cancer Registry. Data on diabetic status and other health problems (comorbidities) were retrieved from Taiwan’s universal health insurance database. This study included a total of 4,390 breast cancer cases, of which 341 (7.7%) had diabetes. This is a lower percentage than that of breast cancer patients in the United States. The results found that breast cancer patients with diabetes had significantly higher mortality rates, both for deaths from breast cancer and for deaths from other causes. The five-year survival rate for breast patients with diabetes was 85%, compared to 91% for breast cancer patients without diabetes.