Endocrine Abstracts

Objective: In acromegaly, high GH/IGF1 levels are associated with abnormal glucose metabolism. Treatment with somatostatin analogues (SSAs) reduces the GH and IFG-1 levels. However, SSAs may worsen glucose homeostasis despite this, due to concomitant inhibition of insulin secretion. We studied the possible association between biochemical cure and glucose homeostasis in de novo patients with acromegaly.

Design: Post hoc analysis from a randomised controlled trial of newly diagnosed acromegalic patients in Norway during 1999–2004.

Methods: 55 de novo patients with acromegaly not using antidiabetic medication were included, 26 received SSA for 6 months preoperatively. HbA1c and an oral glucose tolerance test (OGTT) were performed at diagnosis, before surgery and 3 months postoperatively. Area under curve of glucose (AUC-G) was calculated. Indices of glucose homeostasis were compared between cured and non-cured patients.

Results: No associations between basal IGF1/GH levels and OGTT, (AUC-G) or HbA1c were found. After SSA treatment, the percentage reduction in both mean GH and IGF1 correlated positively with percentage (P=0.021 and P=0.001) and absolute (P=0.0024 and P=0.010) reduction in HbA1c levels. Biochemical cure by IGF1 and nadir GH, or IGF1/nadir GH alone after SSA treatment were also associated with greater absolute reduction in HbA1c levels (P=0.003, P=0.026 and P=0.009 respectively). Three months postoperatively, biochemical cure by IGF1 and nadir GH were associated with reduced (AUC-G) (P=0.041).

Conclusions: In de novo patients with acromegaly, disease activity did not correlate to glucose homeostasis indices. After SSA treatment, reduction of GH and IGF1 and biochemical cure were associated with reduction in HbA1c. Biochemical cure 3 months postoperatively was associated with lower AUC glucose. Thus, hormonal control of GH and IGF1 was associated with improved glucose homeostasis in patients with acromegaly.