Background and Purpose: 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) catalyzes the oxoreduction of cortisone to cortisol, thereby amplifying levels of active glucocorticoids. It is considered a pharmaceutical target in metabolic disease and cognitive impairments. 11β-HSD1 also converts some 7oxo-steroids to their 7β-hydroxy forms. A recent study in mice described the ratio of tauroursodeoxycholic acid (TUDCA)/tauro-7oxolithocholic acid (T7oxoLCA) as a biomarker for decreased 11β-HSD1 oxoreductase activity. The present study aimed to evaluate the equivalent bile acid ratio glycoursodeoxycholic acid (GUDCA)/glyco-7oxolithocholic acid (G7oxoLCA) as a biomarker for pharmacological 11β-HSD1 inhibition in humans and compare it with the currently applied urinary (5α-tetrahydrocortisol+tetrahydrocortisol)/tetrahydrocortisone ((5αTHF+THF)/THE) ratio. Experimental Approach: Bile acid profiles were analyzed by ultra-HPLC tandem-MS in blood samples from two independent, double-blind placebo-controlled clinical studies on the orally administered selective 11β-HSD1 inhibitor AZD4017. The blood GUDCA/G7oxoLCA ratio was compared with the urinary tetrahydro-glucocorticoid ratio for the ability to detect 11β-HSD1 inhibition. Key Results: No significant alterations were observed in the bile acid profiles following 11β-HSD1 inhibition by AZD4017, except for an increase of the secondary bile acid G7oxoLCA. The enzyme product/substrate ratio GUDCA/G7oxoLCA was found to be more reliable to detect 11β-HSD1 inhibition than the absolute G7oxoLCA concentration in both cohorts. Comparison of the blood GUDCA/G7oxoLCA ratio with the urinary (5αTHF+THF)/THE ratio revealed that both ratios successfully detect 11β-HSD1 inhibition. Conclusion and Implications: 11β-HSD1 inhibition does not cause major alterations in bile acid homeostasis. The GUDCA/G7oxoLCA ratio represents the first blood biomarker of pharmacological 11β-HSD1 inhibition and may replace or complement the urinary (5αTHF+THF)/THE ratio biomarker.