We report a 74-year-old white woman with type 1 diabetes and major depressive disorder refractory to multiple medications who received 15 electroconvulsive therapy treatments with minimal improvement. After an accidental hypoglycemic seizure, the patient's symptoms completely resolved. In conclusion, the present case reveals an instance where electroconvulsive therapy-induced seizures appeared to be minimally effective, whereas a single accidental hypoglycemia-induced seizure was incredibly effective for the resolutions of depressive symptoms. Although this case presents a single efficacious use of accidental insulin coma therapy, the applicability is limited because of the known risks of insulin coma therapy.