“Is bipolar disorder an endocrine condition?” Glucose abnormalities in bipolar disorder

The World Health Organisation placed bipolar disorder at the top ten causes of disability worldwide, due not only to its functional impairment but also to its increased medical morbidity and mortality. An increased suicide rate, poor healthcare access, poor health habits, and medication side‐effects contribute to the increased morbidity and mortality. However, the leading contributors to the excess of mortality are cardiovascular pathologies 1, a finding already highlighted by Derby in 1933 in a cohort of manic‐depressive patients admitted to a general hospital. Cardiovascular risk factors, such as obesity, hypertension, type 2 diabetes mellitus (T2DM) 2, and lipid disturbances, are highly increased in bipolar disorder. In between those, glycemic abnormalities are the most repeated finding, taking into account that since the onset of the 20th century, several authors had raised the attention toward an unexpected relationship between manic‐depressive illness and glucose metabolism 3. In addition, the prevalence of T2DM in bipolar disorders ranges from 8% to 17% a threefold increase compared with the general population and bipolar patients with comorbid T2DM may have a more severe course of the psychiatric illness (greater number of depressive and manic episodes, more hospitalizations, and suicidality) and refractoriness to treatment. In addition, studies regarding metabolic disturbances in relatives of bipolar disorder and non‐affective psychosis have described an increased risk of developing glucose abnormalities, adding more scientific background to the unexpected relationship. However, pharmacological treatment, including both antipsychotic agents, antidepressants and mood stabilizers, may have confounded this relationship.