INTRAVENOUS GLUCOSE TOLERANCE TEST TO ASSESS INSULIN SENSITIVITY AND SECRETION IN ACTIVE ACROMEGALY

Active acromegaly is characterized by decreased insulin sensitivity and glucose intolerance. However, an abnormal insulin secretion was not clearly demonstrated. Our objective was to assess insulin sensitivity and secretion using an intravenous glucose tolerance test (IVGTT) in patients with active acromegaly. Seven patients (4 men, 3 women) with active acromegaly underwent a standard IVGTT with a glucose dose of 0.3 g/kg. Five patients had normal glucose tolerance (NGT), 1 had impaired fasting glucose (IFG) and 1 had diabetes mellitus (DM). None were on medication for acromegaly. Subjects with IFG and DM had lower insulin sensitivity than NGT subjects (1.22 vs. 1.67 L min(-1) pmol(-1) 10(6)). Acute insulin response was higher in subjects with NGT compared with patients with IFG or DM (2696 vs. 278 pmol min L-1). Both low insulin secretion and insulin sensitivity contribute to glucose metabolism abnormalities in active acromegaly.