Endocrine Abstracts

Introduction: In normal subjects GH is a hyperglycemic hormone as opposed to insulin-like growth factor 1 (IGF1). Active acromegaly is associated with insulin resistance (IR) and glucose intolerance although both GH and IGF1 are elevated. Our objective was to assess whether GH, IGF1 or both are risk factors for IR and glucose intolerance in acromegaly.

Methods: Basal serum IGF1 and GH, glucose and insulin during an oral glucose tolerance test were measured in 111 patients with active (n=97) or cured (n=14) acromegaly. 53 patients were assessed before any treatment and 58 after surgery and/or radiotherapy. Patients treated with somatostatin analogs, GH-receptor antagonists or antidiabetic drugs were excluded. IR was assessed by various basal and stimulated indices. Glucose intolerance (impaired fasting glucose (n=20), impaired glucose tolerance (n=11) and/or diabetes mellitus (n=12)) was defined according to American Diabetes Association criteria.

Results: Homeostatic model assessment 2-insulin resistance (HOMA2-IR) index correlated more closely with IGF1 (r=0.64, P<0.0001) than nadir (r=0.25, P=0.008) or random GH (r=0.28, P=0.002). Also, IGF1 correlated better than nadir or random GH with all other IR indices (fasting insulin, HOMA1-IR, QUICKI and Matsuda index). In multivariate logistic regression analysis IGF1 (OR=1.55, P=0.01) but not nadir (OR=1, P=0.9) or random (OR=0.99, P=0.9) GH was a significant risk factor for glucose intolerance after adjusting for age, sex, weight and acromegaly duration.

Conclusions: In acromegaly IGF1 correlates more closely than GH with IR. IGF1 levels but not GH are associated with glucose intolerance.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.