Diabetes and cancer are known as two of the most common diseases with significant impacts on the health and well-being of people throughout the world. Epidemiologic evidence has shown that diabetic patients are highly vulnerable to the risk of cancer. There are common risk factors in diabetes and cancer including age, obesity, dietary, physical activity, smoking and alcohol consumption. It has been demonstrated that diabetes imposes a significant impact on cancer through several mechanisms including hyperinsulinemia, hyperglycemia and chronic inflammation. Therefore, understanding the mechanisms involved in the occurrence of diabetes and cancer and their relationship can provide new strategies for the effective prevention, diagnosis and treatment of these diseases.