Assessment of biochemical control of acromegaly during treatment with somatostatin analogues by oral glucose load and insulin-like growth factor I

Background: The use of oral glucose tolerance test (OGTT) in evaluating biochemical control in acromegalic patients on somatostatin analogues (SSA) has recently been questioned. Aim: To gain further insights into this topic, we analyzed basal and nadir GH levels during OGTT in acromegalic patients on SSA. Subjects and methods: Basal IGF-I and GH values, as well as GH levels along the test, were analyzed in 115 standard OGTT performed in 33 acromegalic patients followed up between 1993 and 2009. All patients were on SSA at the time of the study; 22 of them had previously undergone unsuccessful surgery. No patient had undergone radiotherapy. GH suppression was considered normal when the hormonal value fell to 3.9 μg/l displayed lack of GH suppression after OGTT and 80% also displayed high IGF-I. Conversely, patients with basal GH3.9 μg/l are predictive of absent OGTT-dependent GH suppression; however, 20% of these patients display partial biochemical control (normal IGF-I levels). On the other hand, basal GH values