Analyzer

Parents of children with T1D provided demographic and diabetes-specific information during an in-person interview with research staff. Socioeconomic indicators included caregiver education, insurance type, and family structure. Trained medical staff measured the height and weight of children using calibrated scales and stadiometers; age- and sex-adjusted BMI Z score (z-BMI) was calculated using CDC algorithms. Blood pressure (BP) was measured in the sitting position; systolic and diastolic BP percentiles were based on CDC reference ranges [23 (link)]. Glycemic control was assessed by hemoglobin A1c (A1c) using a DCCT-aligned Roche analyzer (reference range 4–6%). The American Diabetes Association (ADA) has established age-specific A1c targets of <8.5% and <8.0% for children aged <6 years and 6–12 years, respectively [24 (link)]. Children with T1D were further categorized as meeting or not meeting A1c targets as established by the American Diabetes Association (ADA).

Blood samples were taken by a clinic nurse one week after enrollment to determine serum concentrations of CRP, IL-6, and blood lipid levels. Samples were processed immediately and stored at −70 degrees Celsius until analyzed by a commercial laboratory. Single-molecule counting technology was used for measurement of IL-6.^¶ This approach to molecular counting technology has been described previously and has a lower limit of quantification of 0.08 pg/mL.^{30 (link)} hs-CRP measurements were performed using a Roche analyzer.^# Both CRP and IL-6 were analyzed as continuous variables.

Serum GGT was measured through an enzymatic colorimetric assay using a Roche analyzer (Roche Diagnostics, GmbH, Mannheim, Germany). The minimum detectable threshold was 3 U/L and the measure range was 3–1200 U/L. The intra-assay coefficient of variation (CV) was 1.5% and the inter-assay CV was 1.4%. The normal values considered for GGT were: 10–50 U/L in men and 10–38 U/L in women. Oxidized LDL was measured using an enzyme-linked immunoassay (ELISA) kit (Mercodia AB, Uppsale, Sweden). The intra-assay and the inter-assay CV was 6% and 5%, respectively. High sensitivity C-reactive protein (CRP) was measured by a colorimetric competitive immunoassay that uses purified protein and polyclonal anti-CRP antibodies. The minimum detectable threshold was 0.03 mg/L and the inter-assay CV was 5%. Homocysteine were measured by fluorimetric polarized immunoassay method (IMX, Abbott Laboratories). The minimum detectable threshold was 0.5 µmol/L and the inter-assay CV was 4.3%.