It is inconclusive whether diabetes and cancer are blood brothers, but they are closely linked. 1.A large number of epidemiological studies have confirmed that primary type 2 diabetes can increase the risk of several common cancers (liver, pancreatic, endometrial, colorectal, breast, bladder), but decrease the risk of prostate cancer. 2. Certain risk factors common to diabetes and cancer: older age at onset, obesity, unreasonable diet, lack of physical exercise, etc. 3. Hyperinsulinemia, hyperglycemia, and inflammation all increase the risk of cancer. 4. Diabetes can also affect the clinical prognosis of certain cancers. 5. Whether diabetes treatment increases the risk of cancer development is an important issue. There is limited evidence, but early evidence suggests that metformin has a role in reducing the risk of cancer development, while exogenous insulin increases the risk of cancer, and further evaluation is needed to determine whether glycosylated insulin increases the risk of cancer development. Recommendations: Patients should be treated for diabetes in general, but patients with a high risk of cancer development (or recurrence) need to be carefully considered for their suitability for diabetes treatment, and active treatment is needed to encourage patients with pancreatic cancer to receive specialized consultation, such as participating in appropriate cancer screening.