Close relation of fasting insulin-like growth factor binding protein-1 (IGFBP-1) with glucose tolerance and cardiovascular risk in two populations

Aims/hypothesis. Insulin resistance/hyperinsulinaemia is implicated in the development of cardiovascular disease and diabetes but its role and causal pathways are not clear. We tested the hypothesis that the insulin-like growth factor system is independently associated with cardiovascular risk within susceptible populations based on previous reports of the links between low circulating insulin-like growth factor binding protein-1 concentrations and increased macrovascular disease in Type II (non-insulin-dependent) diabetes mellitus. Methods. In a population-based study 272 subjects (142 subjects of European and 130 Pakistani of origin) underwent a 75 g oral glucose tolerance test and standardised anthropometry. Fasting concentrations of insulin-like growth factor binding protein-1 (IG-FBP-1), insulin-like growth factor-I (IGF-I), insulin-like growth factor-II (IGF-II), intact insulin and lipids were measured and were related to 2-h glucose tolerance test status. Insulin sensitivity was calculated using the homeostasis model assessment (HOMA). Results. Insulin-like growth factor binding protein-1 was significantly lower in subjects with impaired glucose tolerance when compared with normal glucose tolerance in both ethnic groups (Europeans F = 6.7, p = 0.002 and Pakistanis F = 4.4, p = 0.01). Multiple linear regression modelling showed that insulin-like growth factor binding protein-1 was independently associated with 2-h glucose (β = 0.16, p = 0.009) and logistic regression indicated a 40% reduction in risk of impaired glucose tolerance for every 2.7 ng/ml increase in the insulin-like growth factor binding protein-1 concentration [odds ratio 0.6 (CI = 0.49-0.71), p = 0.001)]. In addition, insulin-like growth factor binding protein-1 was significantly correlated negatively with several established cardiovascular factors, and positively with insulin sensitivity. Conclusion/interpretation. Insulin-like growth factor binding protein-1 is closely related to risk factors for diabetes and cardiovascular disease in people of European and Pakistani origin. It has potential use as a marker of (hepatic) insulin resistance in clinical intervention studies and further implicates the insulin-like growth factor system in the development of macrovascular disease.