OBJECTIVE: To investigate school absenteeism before the clinical diagnosis of type 1 diabetes in children who develop the disease.

RESEARCH DESIGN AND METHODS: This population-based, retrospective case-control study involved all Danish children who developed type 1 diabetes and attended public schools (n = 1,338) from 2010 to 2017. Those children were matched at a 1-to-5 ratio, on the basis of sex and date of birth, to children without diabetes (n = 6,690). Case and control absenteeism were compared monthly, starting with 12 months prior to the type 1 diabetes diagnosis through 12 months after diagnosis.

RESULTS: Before the diabetes diagnosis (7-12 months), the mean number of days absent from school per month was 0.93 (SD 1.78) among children with diabetes and 0.93 (1.82) among control children (difference -0.004 days, P = 0.94). From 4 months before the diagnosis, children who developed diabetes had a statistically significant increase in absenteeism compared with control children (difference 0.24 days, P < 0.05).

CONCLUSIONS: Children who were diagnosed with type 1 diabetes had increased school absenteeism 4 months before diagnosis.