Surgical outcomes and predictors of glucose metabolism alterations for growth hormone-secreting pituitary adenomas: a hospital-based study of 151 cases

Purpose The surgical outcome on glucose metabolism in acromegaly patients is not fully understood. We aimed to investigate the impact of surgery on glucose metabolism and identify key factors that influence alterations of glucose metabolic status in acromegaly patients. Methods Oral glucose tolerance test was performed in 151 newly diagnosed acromegaly patients before and 3–12 months after surgery. Insulin resistance and insulin secretion was assessed. Patients were grouped as cured, discordant, and having active disease according to postoperative growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels. Receiver-operating characteristic curves were generated to determine the optimal cut-off points to predict the impact of surgery on glucose metabolism. Results At baseline, 32.5%, 41.7%, and 25.8% patients were categorized as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetes mellitus (DM), respectively. After surgery, improved glucose tolerance was observed in 87.3% patients with IGT and 66.7% patients with DM. Deterioration was observed in 14.3% patients with NGT. Glucose tolerance improved in patients with lower preoperative FBG, 2 h-BG, and HbA1c and higher HOMA-β and IGI/IR. The proportion of NGT was significantly increased in surgically cured patients (28.3% vs. 79.2%, P < 0.001) and those with normal GH but elevated IGF-1 levels (25.6% vs. 79.5%, P < 0.001), but not in patients with active disease (42.9% vs. 57.1%, P = 0.131). Baseline FBG < 6.35 mmol/l predicted improved glucose metabolism after surgery. Conclusions Glucose metabolic status improved in patients with preserved β-cell function. Preoperative FBG was an independent predictor for improved glucose tolerance status after surgery.