Insulin resistance in bipolar disorder: A systematic review of illness course and clinical correlates

Although insulin resistance (IR) and cardiometabolic syndrome are prevalent in patients with bipolar disorder (BD), only a few studies have attempted to precisely assess the degree and clinical impact of IR in BD. A comprehensive search was conducted from multiple research databases through May 2022, following a pre-defined protocol (PROSPERO: CRD42022359259). We extracted neuroimaging, cognition, illness course, and treatment response findings from individuals with BD with evidence of IR compared with euglycemic BD individuals. Of 1436 identified articles, 10 reports fulfilling inclusion criteria were included (n = 1183). BD patients with IR displayed worse composite verbal memory scores and worse executive function and exhibited smaller hippocampal volumes along with prefrontal neurochemical alterations compared to euglycemic BD patients. Fixed-effect meta-analysis revealed that BD patients with impaired glucose metabolism (IGM) were more likely to develop a chronic and rapid cycling course when compared with euglycemic BD patients (k = 2, OR = 2.96, 95 % CI 1.69–5.17, OR = 2.88, 95 % CI 1.59–5.21, p