Purpose: Elevated circulating insulin-like growth factor I (IGF-I) levels increasingly are being implicated as a potential risk factor for the development of some cancers; however, relatively few epidemiologic studies have focused on potential relationships between circulating IGF-I levels and cardiovascular risk factors or cardiovascular disease. Hence, our objective is to examine relationships between IGF-I levels; body mass index (BMI); fasting insulin level; IGF binding protein 1 (IGFBP-1), IGFBP-2, and IGFBP-3 levels; and an array of traditional cardiovascular risk factors.
Methods: Our analysis included 715 men and women aged 30 to 62 years who participated in the Västerbotten Intervention Project cohort. IGF-I and IGFBP-1, -2, and -3 were measured in stored plasma samples. Cardiovascular risk factors of interest included glucose level (fasting and 2-hour postload), lipid levels (total cholesterol, high-density lipoprotein cholesterol, and triglycerides), blood pressure (systolic and diastolic), and hypertension status. All presented results were adjusted for age, sex, and laboratory batch.
Results: IGF-I quartile was associated inversely with 2-hour glucose level and diastolic blood pressure. There was a stepwise inverse graded association between increasing IGF-I quartile and hypertension, with an odds ratio of 0.51 (95% confidence interval, 0.29-0.90) for hypertension comparing the fourth IGF-I quartile with the first. Further adjusting for BMI and IGFBP-3 level simultaneously strengthened the inverse association, with an odds ratio of 0.42 (95% confidence interval, 0.22-0.80) for hypertension comparing the fourth with the first IGF-I quartile.
Conclusions: Contrary to positive associations between IGF-I levels and some cancers, our results suggest that IGF-I level may be related inversely to prevalent hypertension, a risk factor for cardiovascular disease.