Elevated serum growth hormone in a patient with Type 1 diabetes: a diagnostic dilemma

The biochemical confirmation of acromegaly is rarely difficult and is based on an elevated fasting serum growth hormone (GH) concentration, which fail s to suppress in response to an oral glucose load. Impaired glucose toleran ce and Type 2 diabetes are common in patients with acromegaly, however the development of acromegaly in a patient with pre-existing Type 1 diabetes ha s not been well documented. Poorly controlled Type 1 diabetes in non-acrome galic patients is associated with dysregulation of the hypothalamic-GH/insu lin-like growth factor-1 (IGF-1) axis, leading to elevation of serum GH con centrations. Therefore the diagnosis of acromegaly in a Type 1 diabetic pat ient may be fraught with practical difficulties in performing and interpret ing the results of an oral glucose tolerance test (OGTT) and other biochemi cal investigations. When, in addition, the clinical and radiological featur es of acromegaly are equivocal, the clinician is faced with a formidable di agnostic challenge. In this paper we report such a case, review the pathoph ysiology of hypersomatotrophinaemia in poorly controlled Type 1 diabetes, a nd recommend a diagnostic algorithm for the investigation of acromegaly in patients with diabetes. Copyright (C) 2000 John Wiley & Sons, Ltd.