High-dose insulin therapy is an effective treatment for cardiogenic shock caused by the overdose of particular medications. Other treatment options are usually of limited benefit. Consensus suggests that early initiation improves efficacy. No ceiling effect has been established at doses in the general range of 0.5–10 units/kg/hour. A 79-year-old man presented in cardiogenic shock after an intentional overdose of numerous cardioactive medications 10 days after experiencing myocardial infarction. A high-dose insulin infusion was commenced. This was titrated up to a maximum of 20 units/kg/hour (1600 units/hour) and sustained for 32 h (61,334 units total). Minimal adverse events were seen despite this exceptional infusion rate (3 episodes of hypoglycemia and 2 episodes of hypokalemia). Concurrent catecholamine support was used, and cardiovascular function was maintained until all support was withdrawn 5 days after admission. Emergency physicians are pivotal to the successful initiation/up-titration of high-dose insulin therapy. They must balance the potential for treatment failure with other treatment options, mitigate against adverse events in the initial phase of therapy, and coordinate care between other hospital specialties. This case shows that the relative safety and efficacy was extended to an infusion rate of 20 units/kg/hour, the highest recorded in the published literature. This information may help guide treatment of similar cases in the future.