title: Parental history of diabetes in a population-based study.
abstract: OBJECTIVE
  To evaluate the relative frequency of parental history of diabetes in a population-based study of younger- and older-onset groups of individuals with diabetes and a comparison group of individuals without diabetes.
  
  
  METHODS
  Study participants were queried about a family history of diabetes. The frequencies of positive responses for parents and siblings were compared between younger- and older-onset groups.
  
  
  RESULTS
  At least one parent had diabetes in 18.6% of the families of younger-onset individuals and in 38.6% of the families of older-onset individuals. For those of younger-onset diabetes, 9.1% of fathers, 8.3% of mothers, and 1.3% of both parents had diabetes; the corresponding percentage for those of older-onset diabetes were 11.5, 23.5, and 3.6%, respectively. The difference between frequencies in mothers and fathers was significant (P < 0.0001) in the older-onset group. In the nondiabetic comparison group, for those of similar ages to the younger- and older-onset groups, the corresponding frequencies were 6.2 and 9.0% and 7.7 and 9.8% for fathers and mothers, respectively. The greater frequencies of diabetes in mothers of older-onset diabetic individuals were not accounted for by maternal age. In younger-onset individuals, the relative risk (RR) of diabetes in a sibling if the father had diabetes was 1.22 (95% CI, 0.72-2.05); if the mother had diabetes, the RR was 2.39 (95% CI, 1.64-3.48); and, if both parents had diabetes, the RR was 5.61 (95% CI, 3.37-9.34). In the older-onset individuals, the corresponding RR values were 1.69 (95% CI, 1.35-2.13) for fathers, 1.72 (95% CI, 1.44-2.06) for mothers, and 2.42 (95% CI, 1.81-3.25) for both parents.
  
  
  CONCLUSIONS
  These data confirm a familial influence on the frequency of diabetes. The excess of cases in mothers of older-onset diabetic individuals is compatible with both environmental and genetic influences.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison 53705-2397, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Klein
authors.forename: R
authors.initials: R
authors.lastname: Klein
authors.forename: S E
authors.initials: SE
authors.lastname: Moss
authors.forename: K J
authors.initials: KJ
authors.lastname: Cruickshanks
mesh_terms: D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000704:Analysis of Variance; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000235:genetics*; D005220:Fathers; D005260:Female; D018392:Genomic Imprinting; D006801:Humans; D008297:Male; D008875:Middle Aged; D009035:Mothers; D009679:Nuclear Family; D015995:Prevalence; D014922:Wisconsin / Q000453:epidemiology