['Individuals with bipolar disorder face a nearly two-fold increased risk of cardiovascular mortality relative to the general population. Endothelial dysfunction precedes cardiovascular disease and serves as a quantifiable phenotype for vasculopathy. We investigated whether individuals with bipolar disorder had poorer vascular function than controls using a case-control design.', 'The sample of 54 participants included 27 individuals with bipolar disorder and 27 age- and gender-matched controls. Participants underwent an assessment of metabolic (weight, lipids, and insulin resistance) and vascular parameters (endothelial function using flow-mediated dilation; arterial stiffness using pulse wave velocity and estimated aortic pressure).', 'Participants had a mean age of 32 years and 41% were female. No significant differences were found between groups in endothelial function or arterial stiffness. Individuals with bipolar disorder demonstrated 100% greater insulin resistance.'] Is vascular function impaired early in the course of bipolar disorder?