A 28-year-old man with type 1 diabetes mellitus was admitted for shock and coma due to diabetic ketoacidosis. Despite aggressive treatment and management of the patient's underlying clinical issues, the patient remained in a comatose state. Further investigations revealed an excess consumption of psychotropic agents; however, there was no evidence of an insulin overdose. Physicians should be aware that, in patients who are highly dependent upon insulin, an overdose of psychotropic agents can lead to hypoxic-ischemic brain injury.