Insulin, Glucagon and Growth Hormone and CIMT in Glucose Intolerance

Abstract

Objective: There is an increasing evidence that glucagon and growth hormone (GH)-insulin-like growth factor (IGF) axis may play an important role in glucose metabolism since early stages of glucose intolerance. Carotid intima media thickness is a marker for subclinical atherosclerosis. We aimed to evaluate glucagon, GH and IGF-1 in prediabetic states and their relationship with carotid intima media thickness.

Methods: One hundred subjects underwent a 75 gr oral glucose tolerance test and were divided into 4 groups according to their state of glucose tolerance: (i) normal glucose tolerance (NGT)/Controls (n=21), (ii) impaired glucose tolerance (IGT) (n=35), (iii) impaired fasting glucose (IFG) (n=22), (iv) type 2 diabetes mellitus (n=22). Insulin, glucagon and GH were measured at 0, 60 and 120. minutes of OGTT and their area under the curve (AUC) were calculated. Fasting IGF-1 levels and carotid intima media thickness were determined in all participants.

Results: AUC for Glucagon was significantly higher in subjects with IGT, IFG and type 2 diabetes mellitus compared to NGT subjects. AUC for GH was significantly higher in subjects with IFG compared to subjects with IGT, type 2 diabetes mellitus and NGT. Plasma IGF-1 levels were significantly lower in subjects with abnormal glucose tolerance. CIMT was significantly higher in IFG group and CIMT was found to be negatively correlated with IGF-1 levels in subjects with IFG.

Conclusion: There are pathological alterations of glucagon, GH-IGF-1 and insulin in prediabetic stages. Among these alterations insulin resistance and IGF-1 are associated with CIMT. Further studies needed to investigate the role of treatments targeting insulin sensitivity will have an impact on the association between insulin and early atherogenesis