Positive Metabolic Impact of Treatment with Pegvisomant in an Acromegalic Patient

Abstract

Background: Glucose intolerance and diabetes mellitus are important complications of acromegaly. Somatostatin analogues (SSAs) exert a dual effect on carbohydrate metabolism. Normalisation of the growth hormone/insulin-like growth factor I (GH/IGF-I) axis could improve metabolic balance, but inhibition of insulin secretion could worsen glucose tolerance. Case Description: We report a case of an acromegalic patient with diabetes mellitus that was resistant to SSA therapy. Results: Treatment with SSAs typically induces mild reductions in GH and IGF-I levels, but rarely results in normalisation of these parameters. In addition, glucose levels as well as glycosylated haemoglobin levels (HbA_1c) show marked deterioration. In contrast, pegvisomant (PEG) treatment normalises IGF-I levels, and glucose, insulin and HbA_1c levels gradually decrease. During SSA therapy, this patient required an increase in the dose and type of hypoglycaemic agents. During PEG treatment, however, hypoglycaemic drugs are often reduced. Conclusion: Patients with acromegaly whose disease is inadequately controlled by SSA therapy can achieve normalisation of IGF-I levels and full control of the disease, including strong improvement of glucose homeostasis despite marked reduction of antidiabetic therapy, when treated with the GH antagonist, PEG.