Relationship Between Serum Igf-1 And Bmi Differs By Age

Background: Serum levels of insulin-like growth factor 1 (IGF-1) and body mass index (BMI) are both associated with susceptibility to age-related diseases. Reports on the correlation between them have been conflicting, with both positive to negative correlations reported. However, the age ranges of the participants varied widely among these studies.Methods: Using data on 4241 participants (aged 24-110) from the Long Life Family Study, we investigated the relationship between IGF-1 and BMI by age groups using regression analysis.Results: When stratified by age quartile, the relationship between IGF-1 and BMI varied: in the first quartile (Q1, 20-58 years) the relationship was negative (beta = -0.2, p = .002); in Q2 (58-66 years) and Q3 (67-86 years) the relationship was negative (beta = -0.07, beta = -0.01, respectively) but nonsignificant; and in Q4 (87-110 years) the relationship was positive (beta = 0.31, p = .0002). This pattern did not differ by sex. We observed a similar age-related pattern between IGF-1 and BMI among participants in the third National Health and Nutritional Examination Survey.Conclusions: Our results that the relationship between IGF-1 and BMI differs by age may explain some of the inconsistency in reports about their relationship and encourage additional studies to understand the mechanisms underlying it.