Objective: Studies have suggested that the age at diagnosis of Type 1 diabetes (T1D) is decreasing over time. The overload hypothesis postulates that risk factors, such as accelerated growth, may be responsible for this decrease. We assessed changes in age, body mass index (BMI), weight and height at diagnosis with T1D in non-Hispanic white (NHW) and Hispanic (HISP) young people from Colorado, using data from the IDDM Registry and SEARCH Study.
Methods: In three time periods, 656 (1978-1983), 562 (1984-1988) and 712 (2002-2004) young people aged 2-17 years were newly diagnosed with T1D. Age, weight, height and presence of diabetic ketoacidosis (DKA) at diagnosis with T1D were obtained from medical records. Trends over the three time periods were assessed with regression analyses.
Results: Age at diagnosis decreased by 9.6 months over time (P = 0.0002). Mean BMI standard deviation score (SDS), weight SDS and height SDS increased over time (P < 0.0001), while prevalence of DKA decreased (P < 0.0001). Increasing height over time accounted for 15% (P = 0.04) of the decreasing age at diagnosis with T1D.
Conclusions: Our study provides evidence that increased linear growth, but not increased BMI or weight over time, may account, at least in part, for the younger age at diagnosis of T1D in Colorado children. This finding supports the hypothesis that increasing environmental pressure resulting from changes in potentially preventable risk factors may accelerate the onset of T1D in children.