title: Identifying adolescents with high fasting glucose: the importance of adding grandparents' data when assessing family history of diabetes.
abstract: OBJECTIVE
  To evaluate the role of adding grandparents' data to parental information to the assessment of a family history of diabetes, in order to identify adolescents with high fasting glucose.
  
  
  METHODS
  In 2003 we evaluated 1276 population-based 13-year-olds, from Porto, Portugal. The history of diabetes in parents and grandparents was collected using self-reported questionnaires and a clinical evaluation was performed, including a fasting blood sample. The 75th percentile of fasting plasma glucose (FPG=91 mg/dl) was used to create two groups of participants (high vs. low fasting glucose).
  
  
  RESULTS
  No association was found between family history of diabetes (with or without grandparental data) and a high FPG. The sensitivity to identify individuals with high FPG increased from 7.8% to 47.9% when grandparental history was combined with parental data. The positive predictive value was slightly increased (25.2% vs. 27.8%) but the specificity dropped (91.8% vs. 56.4%).
  
  
  CONCLUSIONS
  Combining parental with grandparental history increased the number of adolescents with a positive family history of diabetes and also increased the sensitivity to identify adolescents with high FPG. So, even if it determines a decrease in specificity, grandparental data is relevant when screening for high fasting glucose in adolescents.
authors.affiliation: Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Alameda Professor Hernâni Monteiro, 4200 - 319 Porto Portugal. Electronic address: marbran@gmail.com.
authors.forename: Mariana
authors.initials: M
authors.lastname: Brandão
authors.forename: Carla
authors.initials: C
authors.lastname: Lopes
authors.forename: Elisabete
authors.initials: E
authors.lastname: Ramos
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008297:Male; D008403:Mass Screening; D008487:Medical History Taking; D011174:Portugal; D011236:Prediabetic State / Q000097:blood* / Q000235:genetics*
keywords: Abnormal glycemia; Adolescent; Family history; Type 2 diabetes mellitus