Abnormalities in glucose homeostasis in acromegaly. Does the prevalence of glucose intolerance depend on the level of activity of the disease and the duration of the symptoms?

INTRODUCTION: Acromegaly is characterized not only by disabling symptoms, but also by relevant co-morbidities. Insulin resistance, leading to glucose intolerance is one of the most important contributory factors to the cardiovascular mortality in acromegaly.

MATERIAL AND METHODS: We analysed the records of 220 naïve patients with acromegaly diagnosed at our Department in the years 1995-2007. Diagnosis of active acromegaly was established on the basis of widely recognized criteria. In each patient glucose and insulin concentrations were assessed when fasting and during the 75 g OGTT.

RESULTS: Normoglycaemia existed in 46% of acromegalic patients. Among glucose tolerance abnormalities we found impaired fasting glucose in 19%, impaired glucose tolerance in 15% and overt diabetes mellitus in 20%. There was no statistically significant differences in gender, duration of the disease, basal plasma GH, IGF-1 or fasting insulin concentrations between normoglycaemic patients and those with impairments in glucose tolerance. The groups showed statistically significant differences with respect to age at diagnosis (p < 0.01). There was no significant correlation between GH, IGF-1 concentrations and fasting plasma glucose. There was no correlation between the duration of the disease and fasting plasma glucose. We found a statistically significant correlation between plasma GH, IGF-1 concentrations and HOMA, QUICKI and insulinAUC.

CONCLUSIONS: The prevalence of diabetes mellitus among acromegalics is much higher than in the general population. The occurrence of glucose tolerance impairments does not depend on the duration of the disease. In patients with acromegaly insulin resistance and hyperinsulinemia are positively correlated with the level of activity of the disease.