The IGF system influences prevalence of the metabolic syndrome in a population with high rates of cardiovascular disease
AH Heald1, SG Anderson2, A Vyas2, J Patel2, KW Siddals1, JK Cruickshank2 & JM Gibson2
The metabolic syndrome is associated with an increased risk of cardiovascular disease and diabetes. The insulin-like growth factor (IGF) system has been implicated in the pathogenesis of cardiovascular disease and glucose intolerance. We have previously shown that a low IGFBP-1 concentration coupled with a low circulating IGF-I predicts worsening glucose tolerance. In this study we further investigated relationships between the IGF-system and the metabolic syndrome in an ethnic group with especially high risk of cardiovascular disease.
394 individuals of Gujarati origin were studied and anthropometry, fasting plasma insulin, glucose, lipids, IGF-I, IGFBP-1 and IGFBP-3 measured. 58 subjects were defined as having the metabolic syndrome. This was defined according to National Cholesterol Education Program Adult Treatment Panel III criteria.
Age-adjusted circulating IGFBP-1 was significantly lower in the metabolic syndrome (35.5 (23.2, 47.7) mcg/l vs 46.7 (42.3, 51.0) mcg/l); F=8.9, P=0.003 as was IGF-I (104.4 (89.1, 119.7) vs 121.5 (116.0, 127.0) ng/ml)); F=4.2; P=0.04 and IGFBP-3; F=3.0, P=0.02. Conversely fasting insulin was higher in the metabolic syndrome (14.7 (12.8, 17.0) vs. 10.8 (10.0, 11.6) pmol/l); F=12.6; p=0.004. A univariate logistic regression showed that individuals with the lowest tertile of circulating IGF-I and IGFBP-1 below the median had a 10-fold increase likelihood of having the metabolic syndrome compared with those with the highest tertile of IGF-I and IGFBP-1 above the median (OR=10.7; P<0.05).
The combination of a low IGF-I and low IGFBP-1 is strongly correlated with the presence of the metabolic syndrome providing further evidence for a role for the IGF-system in the pathogenesis of cardiovascular disease.