title: Possible direct influence of complement 3 in decreasing insulin sensitvity in a cohort of overweight and obese subjects.
abstract: A group of 608 apparently healthy patients, 136 men and 472 women, either overweight or obese, aged 18-69 years, were examined. BMI, waist circumference, fasting blood glucose (FBG), insulin, and complement 3 (C3) serum levels were measured; the homeostasis model assessment (HOMAIR) was used to evaluate insulin resistance; and physical activity was quantified by a questionnaire.
  
  
  RESULTS
  HOMAIR showed a positive correlation with BMI (r: 0.478, p < 0.001), waist circumference (r: 0.487, p < 0.001), and C3 (r: 0.445, p < 0.001). Moreover, it was significantly associated with gender (F Fisher = 22.12, p < 0.001), and the mean HOMAIR levels were significantly different among the three groups of physical activity, with the lowest level of insulin resistance at the highest level of physical activity (F=7,31, p < 0.001). A multiple regression analysis was carried out with HOMAIR as the dependent variable and gender, age, BMI, waist circumference, C3 and the level of physical activity as independent variables (fitted model: F = 41.24, P<0.001, R2 = 0.328). HOMAIR maintained an independent association with C3 (β = 0.678, P<0.001), sex (β = 0.189, P<0.001), BMI (β = 0.637, P<0.01), and age (β = -0.004, P<0.05).
  
  
  CONCLUSIONS
  This study of a cohort of overweight and obese subjects has shown that insulin resistance (dependent variable) is positively associated with C3 serum levels, independently of age, gender, anthropometric parameters and physical activity, suggesting that higher C3 serum levels may directly increase insulin resistance in obesity.
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Pergola
authors.forename: Massimo
authors.initials: M
authors.lastname: Tartagni
authors.forename: Nicola
authors.initials: N
authors.lastname: Bartolomeo
authors.forename: Irene
authors.initials: I
authors.lastname: Bruno
authors.forename: Michele
authors.initials: M
authors.lastname: Masiello
authors.forename: Domenico
authors.initials: D
authors.lastname: Caccavo
authors.forename: Serena
authors.initials: S
authors.lastname: Bavaro
authors.affiliation: Clinical Nutrition Unit, Medical Oncology, Department of Biomedical Sciences and Human Oncology, Section of Clinical Oncology, University of Bari, School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124 Bari, Italy. gdepergola@libero.it.
authors.forename: Franco
authors.initials: F
authors.lastname: Silvestris
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D015331:Cohort Studies; D003176:Complement C3 / Q000378:metabolism*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000175:diagnosis; D050177:Overweight / Q000097:blood* / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003176:Complement C3