This narrative review examines evidence linking insulin resistance (IR) and compensatory hyperinsulinemia to increased cardiovascular, cancer, and all-cause mortality, independent of obesity or diabetes status. Drawing on large cohort studies, meta-analyses, and long-term follow-ups in both diabetic and non-diabetic populations, the authors show that elevated fasting insulin and IR indices (including HOMA-IR, TyG, and METS-IR) consistently predict higher mortality risk. These associations persist in normal-weight individuals and often outperform BMI as a risk marker, suggesting insulin exposure itself—not adiposity—is a primary driver of risk. While the paper does not prescribe a single cause, the findings are consistent with the view that insulin resistance represents an adaptive response to chronic carbohydrate excess and sustained insulin demand. The authors argue that IR with hyperinsulinemia should be recognized as an independent pathological state warranting routine screening and early intervention, as failure to address insulin resistance may underlie residual cardiovascular risk and rising chronic disease mortality despite aggressive pharmacologic management.