Gender differences in the relation of insulin-like growth factor binding protein-1 to cardiovascular risk factors: a population-based study

OBJECTIVE: A possible involvement of insulin-like growth factor-I (IGF-I) and its binding protein IGFBP-1 in the pathogenesis of cardiovascular disorder has been suggested. However, few publications have addressed the gender differences in cardiovascular risk factors in relation to the IGF/IGFBP system. The aim of the present study was to study gender differences in the relationship between fasting serum levels of IGFBP-1 and cardiovascular risk factors in a normal population of men and women. DESIGN: Cross-sectional study. Patients A normal population of 273 men and women aged 20-74 years. MEASUREMENTS: A medical examination was performed and blood drawn in the morning after subjects had been fasting overnight. Before the examination, they were asked to fill out a questionnaire concerning lifestyle and psychosocial factors. RESULTS: Fasting IGFBP-1 was lower in men than in women and was positively correlated to age in men but not in women. The men had in general a more disadvantageous cardiovascular risk profile than women, with several indicators of the metabolic syndrome: higher blood pressure and higher serum levels of total cholesterol, triglycerides, low density lipoprotein cholesterol (LDL-C), plasma-glucose and insulin, as well as lower IGFBP-1. Women had lower physical activity, lower consumption of alcohol, and lower values on indicators of psychosocial and mental health but had a healthier diet. Our findings indicate that low circulating levels of IGFBP-1 are associated with the well-known risk factors of cardiovascular disease; however, the association showed a different pattern for men and women. In men we found a negative association with body mass index (BMI), insulin resistance and diastolic blood pressure, and a positive association with SHBG, cortisol and testosterone. For women low IGFBP-1 appears in negative associations with BMI, waist-hip ratio (WHR), insulin resistance and testosterone, and in positive associations with SHBG and cortisol. Significant gender differences in the correlation with IGFBP-1 are seen for testosterone, cortisol, SHBG, WHR and oestradiol. For HDL-C and diastolic blood pressure the gender difference in correlation was at the limit of significance (P < 0.10). CONCLUSION: Low circulating levels of IGFBP-1 are associated with the well-known risk factors of cardiovascular disease; however, the association showed a different pattern for men and women. The most marked gender differences in the correlation with IGFBP-1 are seen for testosterone, cortisol, SHBG, WHR, oestradiol, HDL-C and diastolic blood pressure. Our study emphasizes the importance of separate analyses for men and women. The results presented are a step towards gaining a better understanding of the gender differences in cardiovascular disease and in the regulation of IGFBP-1, though further prospective studies are needed.