A consensus report by the American Diabetes Association and the American Cancer Society reviews the relationship between diabetes and cancer. Epidemiologic evidence suggests that people with diabetes have a higher risk of several cancers, particularly liver, pancreas, and endometrial cancers. Type 2 diabetes shares many risk factors with cancer, and potential biological links between the two diseases are not fully understood. Some diabetes medications may influence cancer risk or prognosis. The report addresses four key questions: 1) Is there a meaningful association between diabetes and cancer incidence or prognosis? 2) What risk factors are common to both diabetes and cancer? 3) What are possible biological links between diabetes and cancer risk? 4) Do diabetes treatments influence cancer risk or prognosis? The report finds that diabetes is associated with increased cancer risk for certain cancers, such as liver, pancreas, and endometrial cancers, but not for others like lung cancer. Diabetes may also be associated with lower risk of prostate cancer. The association between diabetes and cancer prognosis is less clear. Common risk factors for both diseases include obesity, physical inactivity, and aging. Other risk factors include sex, race/ethnicity, and diet. Biological mechanisms that may link diabetes and cancer include hyperinsulinemia, hyperglycemia, and chronic inflammation. The insulin/IGF axis is a key factor, as insulin and IGF-I receptors are expressed in many cancer cells. Hyperinsulinemia may promote cancer by increasing IGF-I levels, which can stimulate cell proliferation and survival. Hyperglycemia may also contribute to cancer progression by providing more glucose for cancer cells. Diabetes treatments, such as metformin, may have anti-cancer effects, while other treatments like sulfonylureas may increase cancer risk. Insulin and insulin analogs may influence cancer risk through their effects on IGF-I receptors. The report highlights the need for further research to clarify the relationship between diabetes and cancer, including the role of specific biological mechanisms and the impact of diabetes treatments on cancer risk and prognosis.A consensus report by the American Diabetes Association and the American Cancer Society reviews the relationship between diabetes and cancer. Epidemiologic evidence suggests that people with diabetes have a higher risk of several cancers, particularly liver, pancreas, and endometrial cancers. Type 2 diabetes shares many risk factors with cancer, and potential biological links between the two diseases are not fully understood. Some diabetes medications may influence cancer risk or prognosis. The report addresses four key questions: 1) Is there a meaningful association between diabetes and cancer incidence or prognosis? 2) What risk factors are common to both diabetes and cancer? 3) What are possible biological links between diabetes and cancer risk? 4) Do diabetes treatments influence cancer risk or prognosis? The report finds that diabetes is associated with increased cancer risk for certain cancers, such as liver, pancreas, and endometrial cancers, but not for others like lung cancer. Diabetes may also be associated with lower risk of prostate cancer. The association between diabetes and cancer prognosis is less clear. Common risk factors for both diseases include obesity, physical inactivity, and aging. Other risk factors include sex, race/ethnicity, and diet. Biological mechanisms that may link diabetes and cancer include hyperinsulinemia, hyperglycemia, and chronic inflammation. The insulin/IGF axis is a key factor, as insulin and IGF-I receptors are expressed in many cancer cells. Hyperinsulinemia may promote cancer by increasing IGF-I levels, which can stimulate cell proliferation and survival. Hyperglycemia may also contribute to cancer progression by providing more glucose for cancer cells. Diabetes treatments, such as metformin, may have anti-cancer effects, while other treatments like sulfonylureas may increase cancer risk. Insulin and insulin analogs may influence cancer risk through their effects on IGF-I receptors. The report highlights the need for further research to clarify the relationship between diabetes and cancer, including the role of specific biological mechanisms and the impact of diabetes treatments on cancer risk and prognosis.