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BACKGROUND Idiopathic intracranial hypertension (IIH) is a condition predominantly affecting obese women of reproductive age. Recent evidence suggests that IIH is a disease of metabolic dysregulation, androgen excess, and an increased risk of cardiovascular morbidity. Here we evaluate systemic and adipose specific metabolic determinants of the IIH phenotype. METHODS In fasted, matched IIH (n = 97) and control (n = 43) patients, we assessed glucose and insulin homeostasis and leptin levels. Body composition was assessed along with an interrogation of adipose tissue function via nuclear magnetic resonance metabolomics and RNA sequencing in paired omental and subcutaneous biopsies in a case-control study. RESULTS We demonstrate an insulin- and leptin-resistant phenotype in IIH in excess of that driven by obesity. Adiposity in IIH is preferentially centripetal and is associated with increased disease activity and insulin resistance. IIH adipocytes appear transcriptionally and metabolically primed toward depot-specific lipogenesis. CONCLUSION These data show that IIH is a metabolic disorder in which adipose tissue dysfunction is a feature of the disease. Managing IIH as a metabolic disease could reduce disease morbidity and improve cardiovascular outcomes. FUNDING This study was supported by the UK NIHR (NIHR-CS-011-028), the UK Medical Research Council (MR/K015184/1), Diabetes UK, Wellcome Trust (104612/Z/14/Z), the Sir Jules Thorn Award, and the Midlands Neuroscience Teaching and Research Fund.

The alpha ketoglutarate-dependent dioxygenase, prolyl-4-hydroxylase 3 (PHD3), is a Hypoxia-Inducible Factor (HIF) target that uses molecular oxygen to hydroxylate peptidyl prolyl residues. While PHD3 has been reported to influence cancer cell metabolism and liver insulin sensitivity, relatively little is known about effects of this highly conserved enzyme in insulin-secreting β-cells in vivo. Here, we show that deletion of PHD3 specifically in β-cells (βPHD3KO) is associated with impaired glucose homeostasis in mice fed high fat diet. In the early stages of dietary fat excess, βPHD3KO islets energetically rewire, leading to defects in the management of pyruvate fate and a shift from glycolysis to increased fatty acid oxidation (FAO). However, under more prolonged metabolic stress, this switch to preferential FAO in βPHD3KO islets is associated with impaired glucose-stimulated ATP/ADP rises, Ca2+ fluxes and insulin secretion. Thus, PHD3 might be a pivotal component of the β-cell glucose metabolism machinery in mice by suppressing the use of fatty acids as a primary fuel source during the early phases of metabolic stress.