title: Insulin-like growth factor I, growth hormone, and insulin sensitivity: the effects of a one-year cholecalciferol supplementation in middle-aged overweight and obese subjects.
abstract: Both altered GH-IGF-I axis and low serum levels of 25-hydroxyvitamin D (25(OH)D) are linked to measures of metabolic syndrome. Our hypothesis was that there is a relation between GH, IGF-I, and 25(OH)D; and that vitamin D supplementation may have an effect on the levels of GH, IGF-I, and IGF-I/IGFBP-3 ratio. 318 overweight and obese subjects completed a one-year randomized intervention with either 40,000 or 20,000 IU cholecalciferol per week or placebo. GH, IGF-I, IGFBP-3 and measures of insulin resistance were evaluated at baseline and at the end of study. There was a significant relation between entities of GH-IGF-I axis and insulin resistance. Subjects with severe obesity had significantly lower serum 25(OH)D and had a significant linear decline in IGF-I/IGFBP-3 ratio with increasing serum 25(OH)D quartiles. Vitamin D status was an independent predictor of GH-IGF-I axis and supplementation with vitamin D decreased IGF-I/IGFBP-3 ratio in subjects without severe obesity. No corresponding effect of vitamin D supplementation on BMI or insulin resistance was observed. Adverse effects of GH-IGF-I axis on glucose metabolism and the development of metabolic syndrome may be in part associated with the changes in vitamin D status.
authors.affiliation: Department of Medicine, University Hospital of North Norway, 9038, Tromsø, Norway. elena.kamycheva@unn.no
authors.forename: Elena
authors.initials: E
authors.lastname: Kamycheva
authors.forename: Vivian
authors.initials: V
authors.lastname: Berg
authors.forename: Rolf
authors.initials: R
authors.lastname: Jorde
mesh_terms: D000328:Adult; D000368:Aged; D002762:Cholecalciferol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D005947:Glucose / Q000378:metabolism; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism / Q000503:physiopathology; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D050177:Overweight / Q000097:blood / Q000503:physiopathology*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D002762:Cholecalciferol; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D005947:Glucose