Total serum insulin-like growth factor-1 and C-reactive protein in metabolic syndrome with or without diabetes

There are only a few data on the relationship of insulin-like growth factor-1 (IGF-1), implicated in glucose homeostasis, and C-reactive protein (CRP), a measure of subclinical systemic inflammation, in patients with the metabolic syndrome (MetS). The authors investigated, in a cross-sectional design, the correlation between total IGF-1 and CRP in 170 subjects. Among them 123 had the MetS (National Cholesterol Program ATP III definition) and 47 did not, and 136 had type 2 diabetes mellitus (DM) and 34 did not. Anthropometric variables, clinical characteristics, as well as laboratory measurements, including total IGF-1 and CRP, were recorded. CRP levels showed a significant negative correlation with total IGF-1 concentrations, both in the whole study population (r = -0.252, p = 0.001) and the MetS group (r = -0.203, p = 0.025), regardless of the presence of DM. This correlation remained significant after adjusting for age, gender, smoking status, and waist circumference (r = -0.18, p = 0.05). Both low IGF-1 and high CRP levels had an almost linear relationship with the number of MetS components (p = 0.029 and p = 0.020, respectively), suggesting a close relationship of both variables with the cardiovascular disease (CVD) risk involved. The correlation between high CRP and low total IGF-1 might indicate that an increase in CRP levels may well be a key factor for the reduction in IGF-1 concentrations. Both factors are related to an increase in risk for MetS and CVD and this finding might have clinical implications in preventing or treating MetS, DM, and CVD. Given the cross-sectional design of the study, this finding should be confirmed by larger prospective and, it is hoped, interventional studies.