Cancer risk increases by 25 to 250% not only in dysmetabolic obese or overweight people with overt type 2 diabetes but also in individuals with intermediate hyperglycemia (pre-diabetes), with especially pronounced risk of pancreatic or hepatocellular cancer and obesity-related cancers, e.g., colorectal and kidney cancers, bladder cancer in men, and endometrial and breast cancers in women. Cancer may often be present before or upon the diagnosis of diabetes, as there is a common pathogenetic dysmetabolic-inflammatory background with insulin resistance for developing diabetes, cardiorenal disease, and cancer in parallel. The mechanisms involved relate to hyperinsulinemia as a potential carcinogenic priming event with ectopic visceral, hepatic, pancreatic, or renal fat accumulation that subsequently fuel inflammation and lipo-oncogenic signals, causing mitochondrial oxidative stress and deregulation. Moreover, hyperinsulinemia may foster mitogenic MAP kinase-related signaling, which can also occur via IGF1 receptors due to increased free IGF1 levels in obesity. Weight reduction of 10% or more in obese people with diabetes or pre-diabetes, e.g., through intensive lifestyle intervention or bariatric (=metabolic) surgery or through treatment with GLP-1 receptor agonists or metformin, is associated with significantly lower incidence of "diabesity"-associated cancers. In conclusion, there seems to be huge utility in adopting the new "Cardio-Renal-Metabolic-Cancer Syndrome" approach, also looking for cancer at the time of diabetes diagnosis in addition to proactively screening for undiagnosed dysglycemia.