Glucocorticoid-induced adrenal insufficiency is caused by exogenous glucocorticoid suppression of the hypothalamic-pituitary-adrenal axis and is the most prevalent form of adrenal insufficiency. The condition is important to diagnose given the risk of life-threatening adrenal crisis and impact on patients’ quality of life. The diagnosis is made with a stimulation test such as the ACTH test. Until now, testing for glucocorticoid-induced adrenal insufficiency has often been based on clinical suspicion rather than routinely but accumulating evidence indicates that a significant number of cases will remain unrecognized. During ongoing oral glucocorticoid treatment or initially after withdrawal, ~50% of patients have adrenal insufficiency, but, outside clinical studies, ≤ 1% of patients have adrenal testing recorded. More than 70% of cases are identified during acute hospital admission, where the diagnosis can easily be missed because symptoms of adrenal insufficiency are nonspecific and overlap those of the underlying and intercurrent conditions. Treatment of severe glucocorticoid-induced adrenal insufficiency should follow the principles for treatment of central adrenal insufficiency. The clinical implications and thus indication to treat mild-moderate adrenal deficiency after glucocorticoid withdrawal has not been established. Also, the indication of adding stress dosages of glucocorticoid during ongoing glucocorticoid treatment remains unclear. In patients with established glucocorticoid-induced adrenal insufficiency, high rates of poor confidence in self-management and delayed glucocorticoid administration in the acute setting with an imminent adrenal crisis call for improved awareness and education of clinicians and patients. This article reviews different facets of glucocorticoid-induced adrenal insufficiency and discusses approaches to the condition in common clinical situations.