title: Seasonal variation in the diagnosis of type 1 diabetes in south-east Sweden.
abstract: With the aim to survey the seasonal pattern of diagnosis of type 1 diabetes we included all 1903 children <16 years of age and who had been diagnosed with type 1 diabetes between 1977 and 2001 in the south-east of Sweden. To investigate the seasonal pattern a mixture of two cosine functions was included in a logistic regression model. There was a clear seasonal variation over the years (p<0.001). Children in the oldest age group (11-15 years) showed the most obvious seasonal variation (p<0.001). Children with a short duration of symptoms had about the same seasonal variation as children with a long duration. Both children with and without an infection 3 months prior to diagnosis showed significant seasonal variation (p<0.001) although the seasonal pattern differed between the two groups (p<0.001). As the incidence of diabetes increased during the 25 years the study period was divided into periods of 5 years and it was only during the two last periods that significant seasonal variation occurred. There is a clear seasonal variation in diagnosis of type 1 diagnosis in children and the results suggest that children with a less aggressive disease process at diagnosis were most responsible for this variation. Children with and without prior infection showed a different seasonal pattern.
authors.affiliation: Division of Paediatrics, Department of Molecular and Clinical Medicine, Linköping University, S-581 85 Linköping, Sweden. ulf.samuelsson@lio.se
authors.forename: U
authors.initials: U
authors.lastname: Samuelsson
authors.forename: J
authors.initials: J
authors.lastname: Carstensen
authors.forename: O
authors.initials: O
authors.lastname: Löfman
authors.forename: S
authors.initials: S
authors.lastname: Nordfeldt
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D017668:Age of Onset; D001424:Bacterial Infections / Q000382:microbiology; D001786:Blood Glucose / Q000032:analysis; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015994:Incidence; D016015:Logistic Models; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D012621:Seasons; D013548:Sweden / Q000453:epidemiology
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin