Age and Sex Influence Cystatin C in Adolescents With and Without Type 1 Diabetes

OBJECTIVE: To compare serum cystatin C levels, a novel biomarker of renal function, in adolescents with and without type 1 diabetes and to determine what factors affect cystatin C levels. RESEARCH DESIGN AND METHODS: Cystatin C was measured in youth 12–19 years of age with (n = 259, diabetes duration 9 ± 3 years, HbA(1c) 8.9 ± 1.6%) and without diabetes (n = 78). Data were compared by diabetes status, and linear regression was used to determine factors affecting cystatin C. RESULTS: Cystatin C (0.698 ± 0.083 vs. 0.688 ± 0.127 mg/L, P = 0.40) was similar by diabetes status. In multiple linear regression, cystatin C was associated with age and serum creatinine in nondiabetic subjects and sex, age, and serum creatinine in subjects with diabetes (P < 0.05). CONCLUSIONS: These data suggest sex differences and age-related changes in cystatin C in adolescents with type 1 diabetes. An understanding of these changes is needed to determine the potential role of cystatin C as a marker of renal function in this population.