Stress hyperglycemia (also called stress diabetes or diabetes of injury) is a medical term referring to transient elevation of the blood glucose due to the stress of illness. It usually resolves spontaneously, but must be distinguished from various forms of diabetes mellitus.

It is often discovered when routine blood chemistry measurements in an ill patient reveal an elevated blood glucose. Blood glucose can be assessed either by a bedside ‘fingerstick’ glucose meter or plasma glucose as performed in a laboratory (the latter being more efficacious). A retrospective cohort study by the Mayo Clinic held that bedside glucometry was a reliable estimate of plasma glucose with a mean difference of 7.9 mg/dL, but still may not coincide with every individual. The glucose is typically in the range of 140–300 mg/dl (7.8-16.7 mM) but occasionally can exceed 500 mg/dl (28 mM), especially if amplified by drugs or intravenous glucose. The blood glucose usually returns to normal within hours unless predisposing drugs and intravenous glucose are continued.