Screening of cushings syndrome in patients with poorly controlled type 2 diabetes with hypertension and obesity

Abstract

INTRODUCTION: Cushing’s syndrome (CS) may be unrecognized in patients with diabetes. There is no consensus on routine screening for CS in patients with type 2 diabetes (T2DM). Aim of the study was to evaluate the prevalence of unsuspected CS in out-patients with diabetes. METHODS: Cross sectional prospective study was conducted at diabetes clinic in National Hospital of Sri Lanka among patients with diabetes who were attending for out-patient visit from January-2016 to January- 2017. Total of 287 patients were investigated with over-night dexamethasone- suppression test (ODST) as a screening test. Patients who fail to suppress serum cortisol less than 50nmol/l were further tested by Low-dose-dexamethasone-suppression test (LDDST). A third step midnight cortisol measurement was performed in patients who were failed to suppress cortisol less than 50nmol/l on LDDST. Fourth step imaging studies with pituitary MRI, abdominal-CT or CT-scan of chest abdomen and pelvis depending on the ACTH levels were performed. RESULTS: Out of 287, 46.18% (133) patients failed to suppress cortisol to less than 50nmol/l on ODST. Among these 133, 23(11.49% of total) patients failed to suppress cortisol less than 50nmol/l on LDDST. Nine out of 23 patients had cortisol more than 140nmol/l on midnight cortisol test, confirming true CS. Further investigations with imaging revealed one with pituitary adenoma, one with adrenal adenoma and 6 had normal imaging. CONCLUSION: Considering the prevalence of definitive CS of 3.18% among poorly controlled T2DM patients with hypertension and obesity suggest that CS is not rare as previously thought. But in our Asian population with T2DM and high prevalence of co-morbidities, taking overnight dexamethasone suppression test alone as a screening test would not be a suitable test to screen CS.