C. Robertson and T. Dunn (2023). "A ghost doesn't need insulin," Cotard's delusion leading to diabetic ketoacidosis and a body-mass index of 15: a case presentation. BMC psychiatry, 23(1), 551. https://doi.org/10.1186/s12888-023-05039-6

PubMed 37525179

[Abstract]
BACKGROUND: Cotard's Syndrome (CS) is a rare clinical entity where patients can report nihilistic, delusional beliefs that they are already dead. Curiously, while weight loss, dehydration, and metabolic derangements have been described as discussed above, a review of the literature revealed neither a single case of a severely underweight patient nor a serious metabolic complication such as Diabetic Ketoacidosis. Further, a search on PubMed revealed no articles discussing the co-occurrence of Cotard's Delusion and eating disorders or comorbid metabolic illnesses such as diabetes mellitus. In order to better examine the association between Cotard's Delusion and comorbid eating disorders and metabolic illness, we will present and discuss a case where Cotard's delusion led to a severe metabolic outcome of DKA and a BMI of 15.

CASE PRESENTATION: Mr. B is a 19 year old transgender man admitted to the hospital due to diabetic ketoacidosis secondary to Type 1 Diabetes Mellitus. Mr. B had a history of Obsessive-Compulsive Disorder, Major Depressive Disorder, and Post-Traumatic Stress Disorder. The primary pediatric team discovered that Mr. B had not been using his insulin appropriately and was severely underweight, and they believed this could be due to his underlying mental illness. The psychiatric consultation/liaison service found that Mr. B was suffering from Cotard's delusion leading him to be noncompliant with his insulin due to a belief that he was already dead. Cotard's delusion had in this case led to a severe metabolic outcome of DKA and a BMI of 15.

CONCLUSIONS: This case provides clinical insight into the interactions of eating disorders and Cotard's delusion as well as the potential medical complications when Cotard's delusion is co-morbid with medical conditions such as Diabetes Mellitus. We recommend that clinicians routinely screen patients for Cotard's delusion and assess whether the presence of which could exacerbate any underlying medical illness. This includes clinicians taking special care in assessing patient's caloric and fluid intake as well as their adherence to medications both psychiatric and medical. Further research could be conducted to explore the potential overlap of Cotard's delusion and eating disorder phenomenology.