['Dysregulation of enzymes that control local tissue steroid metabolism has been implicated in the pathogenesis of obesity and insulin resistance; however, longitudinal changes in glucocorticoid metabolism have not been investigated. This study was performed to evaluate the role of glucocorticoid metabolism in the development of insulin resistance and obesity and to identify biomarkers for future development of metabolic disease.', 'This was a prospective longitudinal observation study conducted over 5 years.', 'A 24-h collection was used to serially analyze urinary glucocorticoid and mineralocorticoid metabolites in 57 obese and overweight patients with no prior diagnosis of diabetes mellitus, recruited from the community.', 'Baseline higher 5α-reductase (5αR) activity, but not 11β-hydroxysteroid dehydrogenase type 1 activity, was predictive of increased fasting insulin at final visit (11.4 compared with 7.4\u200amU/l in subjects with lower 5αR activity, P<0.05), area under the curve insulin response to oral glucose tolerance test (176.7 compared with 89.1\u200amU/l.h, P<0.01), and homeostasis model assessment (HOMA2-IR; 1.3 compared with 0.8, P<0.01). Higher total glucocorticoid production was associated with abnormal glucose tolerance and increased BMI. During this study, systolic blood pressure increased (equivalent to ∼1\u200ammHg/year), as did plasma sodium levels; this evidence of increased mineralocorticoid activity was associated with increased aldosterone metabolites and decreased 11β-hydroxysteroid dehydrogenase type 2 activity.'] Are longitudinal changes in glucocorticoid metabolism associated with later development of adverse metabolic phenotype?