Recent research has highlighted the significant relationship between type 2 diabetes mellitus and cancer, both prevalent and impactful on global health. The intrinsic correlation arises from shared metabolic processes, particularly a systemic and chronic inflammatory state driven by factors like obesity, dyslipidemia, and hyperglycemia. This leads to the creation of a self-sustaining microenvironment known as meta-inflammation, promoting cancer development through DNA damage, oxidative stress, and the influence of hormones like leptin. The hyperglycemic environment in diabetes contributes to cancer development, supporting the Warburg effect and insulin-related mechanisms. This study aims to identify risk factors associated with diabetes that impact tumor development and progression, crucial for guiding effective preventive strategies in clinical practice. Primary objective of the study: \- identify the risk factors affecting the occurrence of cancer in the population affected by type 2 diabetes mellitus; Secondary objectives of the study: * description of the demographic, clinical and first-line therapy characteristics of patients diagnosed with type 2 diabetes mellitus; * assess risk factors for recurrence, presence of a second tumour not related to the first and the presence of both events in patients who have had a tumor within 10 years of diagnosis of diabetes; * assess the relationship between the characteristics of patients and the time to the onset of cancer.