253 The shape and relevance of the oral glucose tolerance test (OGTT) curve in CF

Abstract

Objectives: In normal individuals, the shape of the OGTT curve (monophasic or biphasic) is influenced not only by the glucose load but also the patient’s metabolic response. This has not been studied in CF and may give an insight into the abnormal glucose handling even in those without CFRD. Method: We compared the area under the curve (AUC) for glucose, insulin, C-Peptide and glucagon following a 2-hour OGTT in 13 pancreatic insufficient adult CF (without known CFRD) and 10 healthy subjects, classified according to the OGTT curve shape. Results: See table. Biphasic curves were more common in CF (Chi2 = 4.97, p< 0.03), and these patients also had higher glucagon levels (p = 0.01) compared to their healthy counterparts, whilst CF patients with monophasic curves had reduced C-peptide levels (p = 0.04). Conclusions: This study shows that the shape of the OGTT curve in CF is related to pancreatic alpha and beta-cell function, as well as glucose load. The OGTT shape index may be a useful screening tool to make an early diagnosis of diabetes in CF.