Influence of HbA1c and BMI on Lipid Trajectories in Youths and Young Adults With Type 1 Diabetes

OBJECTIVE To assess the influence of HbA1c 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 HbA1c 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 HbA1c 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 HbA1c level and zBMI and changes in non-HDL levels as youths aged were similar to the associations found with LDL. The influence of HbA1c and zBMI on HDL levels was small and not dependent on age. CONCLUSIONS Changes in HbA1c level and zBMI modestly impact LDL and non-HDL cholesterol and have greater impacts as children age. Addressing elevations in HbA1c and zBMI as children enter into adolescence and beyond may lead to improvements in lipid levels.