Insulin-like growth factor I and impaired glucose tolerance.
The effects of circulating insulin-like growth factor I (IGF-I) on glucose metabolism are well recognized. IGF-I is also important in maintaining beta-cell mass and regulating endogenous growth hormone (GH) levels. Low IGF-I levels could explain links between small birth size and the risk of developing type 2 diabetes mellitus in short, obese adults. In a recent prospective study, childhood insulin secretion was related to IGF-I levels and statural growth, whereas insulin sensitivity was related to early post-natal weight gain. Common genetic polymorphisms in the IGF1 gene have been linked to small birth size, post-natal growth and future diabetes risk, but these results have been inconsistent. Recent adult studies have demonstrated that lower baseline IGF-I levels predict the subsequent development of impaired glucose tolerance (IGT), type 2 diabetes and cardiovascular disease. Administration of low-dose GH therapy, at a dose that minimizes the lipolytic effects of GH and has the ability to increase IGF-I levels, enhances insulin sensitivity in young healthy adults and in GH-deficient adults and increases insulin secretion in individuals with IGT. Whether the administration of low-dose GH, recombinant IGF-I or combined IGF-I/IGF-binding protein 3 therapy prevents future development of IGT or type 2 diabetes in high-risk normoglycaemic and GH-deficient individuals merits further long-term studies.
Dunger
David
D
University Department of Paediatrics, University of Cambridge, Cambridge, UK. dbd25@cam.ac.uk
Yuen
Kevin
K
Ong
Ken
K
D000328:Adult; D000818:Animals; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000235:genetics; D005947:Glucose / Q000378:metabolism*; D018149:Glucose Intolerance / Q000209:etiology* / Q000517:prevention & control; D006130:Growth Disorders / Q000503:physiopathology; D019382:Human Growth Hormone / Q000172:deficiency; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D018969:Insulin-Like Growth Factor Binding Proteins / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*
D018969:Insulin-Like Growth Factor Binding Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D005947:Glucose