Repeated insulin-induced comas have a specific therapeutic effect on schizophrenia.

In the 1930s, psychiatrist Manfred Sakel introduced a dramatic treatment for schizophrenia: large doses of insulin were used to drive patients into severe hypoglycemia and repeated comas, after which glucose was administered to revive them. Reports of striking recoveries helped the method spread internationally.

Treatment units became elaborate medical operations requiring close nursing, repeated procedures and management of seizures and prolonged unconsciousness. That intensity could itself create an impression of powerful biological therapy, while uncontrolled reports made it difficult to separate genuine benefit from selection, supportive care and the natural course of illness.

Better-controlled studies weakened the central claim. In one influential comparison, patients receiving true insulin comas did not fare better than those receiving a safer control treatment designed to mimic parts of the experience without the deep hypoglycemic coma.

The risks were substantial: seizures, brain injury, prolonged coma, metabolic complications and death. The arrival of antipsychotic drugs in the 1950s also offered a more practical alternative and accelerated the treatment’s decline.

The historical failure does not imply that all biological treatments for schizophrenia are invalid. It shows why dramatic intervention and professional enthusiasm cannot substitute for controlled evidence of a specific therapeutic effect.