Background: Type 2 diabetes mellitus (T2DM) alters the risk of developing a variety of cancers, and certain types of cancers impact on developing T2DM. Objective: To investigate the relationship between type 2 DM and cancer, in predicting potential risk factors common to both cancer and diabetes including aging, sex, obesity, and analyze risks of site-specific malignancies associated with T2DM. Patients and methods: This study enrolled a group of patients (2000 patients) who visited Clinical Oncology and Nuclear Medicine Department of Mansura University Hospital divided into 2 group, first group (1000 patients) cancer patients with type 2 diabetes mellitus (group I) and second group (1000 patients) cancer patients without diabetes (group II). Results: Therewas a statistical significant difference as regards of increasing certain type of cancers in T2DM than non-diabetic patients as colorectal carcinoma, cancer breast, uterine carcinoma and hematological malignancy (p < 0.05). However, other types of cancers as cancer prostate, lung cancer and gastric carcinoma were more in non-diabetic patients than T2DM (p < 0.05). Conclusion: Because of changes in lifestyle, the prevalence of diabetes and cancer is increasing at an alarming rate throughout the globe. The relationship between diabetes and cancer development informs us that diabetic individuals have an increased risk of developing cancer, and cancer may cause diabetes through a variety of mechanisms. As a result, research should focus on developing more preventive and therapeutic options for diabetes and cancer patients.