Adverse glycaemic effects of cancer therapy: indications for a rational approach to cancer patients with diabetes.

Diabetes and cancer are common, chronic, and potentially fatal diseases that frequently co-exist. Observational studies have reported an increased risk of cancer in patients with diabetes. Furthermore, many patients with cancer already have diabetes, or develop hyperglycaemia as a consequence of the tumor or of cancer therapies, and coexisting diabetes confers a greater risk of mortality for many malignancies. Managing oncologic patients with diabetes is often complicated, since the co-existence of diabetes and cancer poses several complex clinical questions: what level of glycaemic control to achieve, which therapy to use, how to deal with glucocorticoid therapies and artificial nutrition, how diabetes complications can affect cancer management, which drug-drug interactions should be taken into account, or even how to manage diabetes at the end of life. In the clinical setting, both at hospital and at home, there are little agreed, evidence-based guidelines on the best management and criteria upon which clinical decisions should be based. A practical solution lies in the implementation of care networks based on communication and ongoing collaboration between Oncologists, Endocrinologists, and the nursing staff, with the patient at the centre of the care process. This manuscript aims to review the current evidence on the effect of cancer therapies on glucose metabolism and to address some of the more common challenges of diabetes treatment in patients with cancer.