Positive associations between serum levels of IGF-I and subcutaneous fat depots in young men. The Odense Androgen Study

Abstract

IntroductionSerum levels of IGF-I are of growing interest due to the associations with morbidity and mortality. Despite markedly suppressed GH secretion, total IGF-I levels are often within normal range in obese adults. AimTo study associations between IGF-I and estimated muscle mass in the Odense Androgen Study population and secondly to investigate associations between serum IGF-I and regional fat depots. MethodThe Odense Androgen Study is a population-based, cross-sectional study of 776 randomly selected men aged 20–29years. Regional lean and fat mass were measured by dual-energy X-ray absorptiometry, whereas regional muscle and fat areas were assessed by magnetic resonance imaging. ResultsAge-adjusted IGF-I levels correlated significantly with different estimates of muscle mass (r‐values between 0.15 and 0.19; p<0.001). Using multiple linear regression, serum IGF-I correlated positively with subcutaneous adipose tissue on the abdomen (SAT) after controlling for visceral adipose tissue (VAT) in the whole group and in the subgroup of men with normal waist circumference (r-values between 0.13 and 0.15; p<0.03). In addition, IGF-I correlated positively with subcutaneous thigh fat area (TFA) after controlling for intramyocellular lipid (imcl) r=0.18; p<0.004) and IGF-I correlated negatively with TFAimcl in the whole group and in the subgroup of men with normal waist circumference. ConclusionSAT and subcutaneous TFAs were positively associated with IGF-I in regression analyses. Conversely, imcl of the thigh was inversely associated with IGF-I levels. These findings emphasize the differential associations between IGF-I and regional fat deposits. Future studies may provide further insight regarding the interplay between circulating IGF-I levels and regional muscle and fat mass.