Influence of HbA^sub 1c^ and BMI on Lipid Trajectories in Youths and Young Adults With Type 1 Diabetes

Objective: To assess the influence of HbA^sub 1c^ and BMI (measured as BMI z score [zBMI]) on LDL, HDL, and non-HDL trajectories as youths with type 1 diabetes age into early adulthood. Research design and methods: Dynamic, retrospective cohort study examining changes in lipid values in 572 youths with type 1 diabetes followed longitudinally for a median of 9.3 years. Through longitudinal modeling, we describe the relationship of HbA^sub 1c^ and zBMI on lipid values as subjects age after adjusting for other relevant factors, including lipid-lowering medication use. Results: The median number of lipid assessments was 7 (range 2-39). Every 1% increase in HbA^sub 1c^ was associated with an ~2-6 mg/dL increase in LDL levels, with a greater increase in LDL levels as subjects progressed from prepubertal to postpubertal age ranges. A 1-SD increase in BMI was associated with a mean LDL increase of 2.1 mg/dL when subjects were 10 years old and increased to a mean of 8.2 mg/dL when subjects were 19 years old. The association between changes in HbA^sub 1c^ level and zBMI and changes in non-HDL levels as youths aged were similar to the associations found with LDL. The influence of HbA^sub 1c^ and zBMI on HDL levels was small and not dependent on age. Conclusions: Changes in HbA^sub 1c^ level and zBMI modestly impact LDL and non-HDL cholesterol and have greater impacts as children age. Addressing elevations in HbA^sub 1c^ and zBMI as children enter into adolescence and beyond may lead to improvements in lipid levels.