Nonlinear relationship of insulin-like growth factor (IGF)-I and IGF-I/IGF-binding protein-3 ratio with indices of adiposity and plasma insulin concentrations (Sweden).
OBJECTIVE
In this study we test the hypothesis of a nonlinear relationship of IGF-I with indices of body fat such as body mass index (BMI), insulin, and leptin.


METHODS
The controls used in three case-control cancer studies nested in the Northern Sweden Health and Disease Cohort, were combined for this analysis. Measurements of plasma IGF-I, IGFBP-3, insulin, and leptin were available for 445 men and 391 women.


RESULTS
In both men and women we found the highest mean IGF-I levels in subjects with BMI between 24 and 26. IGF-I concentrations decreased toward BMI < or = 20 and BMI > 30 in men; however, the results for women did not reach statistical significance. The molar ratio of IGF-I/IGFBP-3 showed a similar profile to that of IGF-I, although much less pronounced. The observed peak mean IGF-I levels in the second quintiles of insulin and leptin in men supported these findings. No significant variation of mean IGF-I levels across quintiles of insulin and leptin were observed in women.


CONCLUSIONS
The results of this study provide evidence that IGF-I plasma concentrations vary substantially over a wide range of body weight and that the relationship is nonlinear.
Department of Nutrition and Cancer, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France. lukanova@iarc.fr
Annekatrin
A
Lukanova
Stefan
S
Söderberg
Pär
P
Stattin
Richard
R
Palmqvist
Eva
E
Lundin
Carine
C
Biessy
Sabina
S
Rinaldi
Elio
E
Riboli
Göran
G
Hallmans
Rudolf
R
Kaaks
D000273:Adipose Tissue / Q000378:metabolism*; D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D009765:Obesity / Q000097:blood* / Q000378:metabolism; D012016:Reference Values; D013548:Sweden
D007328:Insulin; D018972:Insulin-Like Growth Factor Binding Protein 3; D020738:Leptin; D007334:Insulin-Like Growth Factor I