Aims/hypothesis: Studies on the association between air pollution and metabolic control in children and adolescents with type 1 diabetes are rare and findings are inconsistent. We examined the relationship between air pollution variables (particulate matter with an aerodynamic diameter <10 μm [PM10], NO2 and accumulated ozone exposure [O3-AOT]) and metabolic variables (HbA1c and daily insulin dose [U/kg body weight]) in children and adolescents with type 1 diabetes.
Methods: We investigated 37,372 individuals with type 1 diabetes aged <21 years, documented between 2009 and 2014 in 344 German centres of the prospective diabetes follow-up registry (Diabetes-Patienten-Verlaufsdokumentation [DPV]). Long-term air pollution exposure (annual and quinquennial means) data were linked to participants via the five-digit postcode areas of residency. Cross-sectional multivariable regression analysis was used to examine the association between air pollution and metabolic control.
Results: After comprehensive adjustment, an interquartile range increase in O3-AOT was associated with a lower HbA1c (-3.7% [95% CI -4.4, -3.0]). The inverse association between O3-AOT and HbA1c persisted after additional adjustment for degree of urbanisation or additional adjustment for PM10. Moreover, the inverse association remained stable in further sensitivity analyses. No significant associations between HbA1c and PM10 or NO2 were found. No association was observed between any of the three air pollutants and insulin dose.
Conclusions/interpretation: The inverse association between O3-AOT and HbA1c could not be explained by regional differences in diabetes treatment or by other differences between urban and rural areas. Furthermore, our results remained stable in sensitivity analyses. Further studies on the association between air pollution and HbA1c in children and adolescents with type 1 diabetes are needed to confirm our observed association and to elucidate underlying mechanisms.
Keywords: Air pollution; HbA1c; Insulin; Metabolic control; Ozone; Particulate matter; Type 1 diabetes.