title: Possible role of hyperinsulinemia and insulin resistance in lower vitamin D levels in overweight and obese patients.
abstract: A cohort of 66 healthy overweight and obese patients, 53 women and 13 men were examined. Waist circumference and fasting 25(OH)D, insulin, glucose, lipid (cholesterol, HDL cholesterol, and triglyceride), C-reactive protein (CRP), and complement 3 (C3), and 4 (C4) serum concentrations were measured. Insulin resistance was assessed by the homeostasis model assessment (HOMA(IR)).
  
  
  RESULTS
  25(OH)D levels showed a significant negative correlation with BMI (P < 0.01), waist circumference (P < 0.05), fasting insulin (P < 0.01), HOMA(IR) (P < 0.01), triglycerides (P < 0.01), CRP (P < 0.01), C3 (P < 0.05), and C4 (P < 0.05). Multiple regression analyses were performed with 25(OH)D as the dependent variable and BMI (or waist circumferences), fasting insulin (or HOMA(IR)), triglycerides, and CRP (or C3 or C4) as independent variables. Only insulin or HOMA(IR) maintained a significant independent association with 25(OH)D levels, whereas vitamin D did not maintain a significant independent association with CRP or C3 or C4 concentrations.
  
  
  CONCLUSIONS
  The present study, performed in overweight and obese subjects, shows that 25(OH)D levels are negatively associated with inflammatory parameters such as CRP and C3 and C4 levels, but not independently of BMI, body fat distribution, insulin levels, or insulin resistance. Our results suggest that hyperinsulinemia and/or insulin resistance are directly responsible for decrease of 25(OH)D levels in obesity.
authors.affiliation: Clinical Nutrition Unit, Department of Biomedical Sciences and Human Oncology, Section of Clinical Oncology, School of Medicine, University of Bari, Policlinico, Piazza Giulio Cesare 11, 70124 Bari, Italy. gdepergola@libero.it
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Pergola
authors.forename: Alessandro
authors.initials: A
authors.lastname: Nitti
authors.forename: Nicola
authors.initials: N
authors.lastname: Bartolomeo
authors.forename: Antonella
authors.initials: A
authors.lastname: Gesuita
authors.forename: Vito Angelo
authors.initials: VA
authors.lastname: Giagulli
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Triggiani
authors.forename: Edoardo
authors.initials: E
authors.lastname: Guastamacchia
authors.forename: Franco
authors.initials: F
authors.lastname: Silvestris
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D015331:Cohort Studies; D005260:Female; D006728:Hormones / Q000378:metabolism; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood* / Q000150:complications; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000150:complications; D050177:Overweight / Q000097:blood* / Q000150:complications; D014807:Vitamin D / Q000097:blood*; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D006728:Hormones; D007328:Insulin; D008055:Lipids; D014807:Vitamin D; D002097:C-Reactive Protein