title: A low incidence of Type 1 diabetes between 1977 and 2001 in south-eastern Sweden in areas with high population density and which are more deprived.
abstract: OBJECTIVE
  To explore how socioeconomic factors and population density may contribute to the geographical variation of incidence of Type 1 diabetes in children in south-eastern Sweden.
  
  
  METHODS
  All children diagnosed with Type 1 diabetes in south-eastern Sweden during 1977-2001 were defined geographically to their place of residence and were allocated x and y coordinates in the national grid. The population at risk and socioeconomic data were aggregated in 82,000 200-m squares and geocoded likewise. A socioeconomic index was calculated using a signed chi(2) method. Rural-urban gradients were defined by overlay analysis in a geographic information system.
  
  
  RESULTS
  The incidence during the past 25 years has been rising steadily, particularly in the last 6 years. The incidence was highest in areas with a high proportion of small families, of families with a high family income and better education, and this was found both at the time of diagnosis and at the time of birth. In the rural-urban analysis, the lowest incidence was found in the urban area with > 20,000 inhabitants, where there was also a higher frequency of deprivation.
  
  
  CONCLUSIONS
  Our findings indicate that geographical variations in incidence rates of Type 1 diabetes in children are associated with socioeconomic factors and population density, although other contributing factors remain to be explained.
authors.affiliation: Division of Paediatrics, Department of Molecular and Clinical Medicine, Linkoping University, Linkoping, Sweden.britt-marie.holmqvist@lio.se
authors.forename: B-M
authors.initials: BM
authors.lastname: Holmqvist
authors.forename: O
authors.initials: O
authors.lastname: Lofman
authors.forename: U
authors.initials: U
authors.lastname: Samuelsson
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012424:Rural Population / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D013548:Sweden / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data*