Endocrine Abstracts

Introduction: Recent reports showed that 2–9.4% of diabetic patients have Cushing’s syndrome (CS) including its mild form, subclinical CS (subCS), but there is no report about screening of acromegaly in diabetic patients. Either 1-mg or 0.5-mg dexamethasone suppression test (DST) is used as the screening test of adrenal CS or Cushing’s disease (CD). The aim of the present study was to screen CS including CD and acromegaly in Japanese diabetic patients.

Design, patients, and measurement: We prospectively evaluated consecutive 225 diabetic patients who were admitted in our affiliated hospitals from November 2008 to March 2010. No patient had clear acromegalic or Cushingoid features. Screening was performed using by 0.5-mg and 1-mg DST as well as measurement of serum IGF1 concentration. The threshold of adequate suppression after either DST was set at 80 nmol/l.

Results: Thirty-six patients failed to suppress cortisol after 0.5-mg DST. One showed positive result in 1-mg DST. Twenty-four patients demonstrated additional diagnostic examinations. Five and one patient met Japanese subclinical CD (sub CD) and subCS criteria respectively, while none of these patients had a positive imaging study. On the other hand, in eighteen patients, the serum IGF1 levels were exceeded age- and sex-specific range. In one woman, definitive diagnosis of acromegaly was made by a surgically proven pituitary GH-producing adenoma.

Conclusions: The present study showed that many diabetic patients have positive CS screening test, and considerable number of patients may have subCD or subCS despite no definitive image findings. Meanwhile, this study is the first demonstration that screening for acromegaly may be feasible in a cohort of diabetic patients. Early diagnosis and treatment of acromegaly may provide the opportunity to improve the prognosis of diabetes, therefore, we simply recommend to measure serum IGF1 levels in all diabetic patients to screen acromegaly.