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 fails to suppress in response to an oral glucose load. Impaired glucose tolerance and Type 2 diabetes are common in patients with acromegaly, however the development of acromegaly in a patient with pre-existing Type 1 diabetes has not been well documented. Poorly controlled Type 1 diabetes in non-acromegalic patients is associated with dysregulation of the hypothalamic-GH/insulin-like growth factor-1 (IGF-1) axis, leading to elevation of serum GH concentrations. Therefore the diagnosis of acromegaly in a Type 1 diabetic patient may be fraught with practical difficulties in performing and interpreting the results of an oral glucose tolerance test (OGTT) and other biochemical investigations. When, in addition, the clinical and radiological features of acromegaly are equivocal, the clinician is faced with a formidable diagnostic challenge. In this paper we report such a case, review the pathophysiology of hypersomatotrophinaemia in poorly controlled Type 1 diabetes, and recommend a diagnostic algorithm for the investigation of acromegaly in patients with diabetes. Copyright 2000 John Wiley & Sons, Ltd.