BackgroundPatients with Cushing’s disease (CD) in remission maintain an increased cardiovascular risk. Impaired characteristics of gut microbiome (dysbiosis) have been associated with several cardiometabolic risk factors.MethodsTwenty-eight female non-diabetic patients with CD in remission with a mean ± SD) age of 51 ± 9 years, mean ( ± SD) BMI, 26 ± 4, median (IQR) duration of remission, 11(4) years and 24 gender-, age, BMI–matched controls were included. The V4 region of the bacterial 16S rDNA was PCR amplified and sequenced to analyse microbial alpha diversity (Chao 1 index, observed number of species, Shannon index) and beta diversity analysis through the Principal Coordinates Analysis (PCoA) of weighted and unweighted UniFrac distances. Inter-group difference in microbiome composition was analysed using MaAsLin2.ResultsThe Chao 1 index was lower in CD as compared with controls (Kruskal-Wallis test, q = 0.002), indicating lower microbial richness in the former. Beta diversity analysis showed that faecal samples from CS patients clustered together and separated from the controls (Adonis test, p<0.05).Collinsella, a genus form of the Actinobacteria phylum was present in CD patients only, whereasSutterella, a genus fromProteobacteria phylum, was scarcely detectable/undetectable in CD patients as well asLachnospira, a genus of theLachnospiraceaefamily of theFirmicutesphylum. In CS, the Chao 1 index was associated with fibrinogen levels and inversely correlated with both triglyceride concentrations and the HOMA-IR index (p<0.05).ConclusionsPatients with CS in remission have gut microbial dysbiosis which may be one of the mechanisms whereby cardiometabolic dysfunctions persist after “cure”.