Serum 1,5-anhydroglucitol (1,5-AG) is a marker of hyperglycemic excursions in adults with diabetes and hemoglobin A1c (HbA1c) < 8%. We compared 1,5-AG levels among youth and young adults with and without type 1 diabetes (T1D) and investigated the utility of 1,5-AG in the assessment of glycemic status in pediatric T1D. We compared 1,5-AG, HbA1c, and plasma glucose levels in 138 patients with T1D (duration ≥1 yr) and 136 healthy controls, aged 10-30 yr. Within each group, we investigated associations between 1,5-AG and clinical characteristics, HbA1c and random plasma glucose. For patients with T1D, 1,5-AG was further analyzed according to HbA1c strata: <8, 8-9, and >9%. Compared to controls, patients with T1D had higher HbA1c (8.5 ± 1.6 vs. 5.1 ± 0.4%, p < 0.0001), lower 1,5-AG (4.0 ± 2.0 vs. 24.7 ± 6.4 µg/mL, p < 0.0001), and higher glucose (11.1 ± 5.2 vs. 5.1 ± 0.9 mmol/L, p < 0.0001). Males had higher 1,5-AG than females within patients (4.5 ± 2.3 vs. 3.4 ± 1.6 µg/mL, p = 0.003) and controls (26.0 ± 6.6 vs. 23.5 ± 6.0 µg/mL, p = 0.02). 1,5-AG was not correlated with glucose in either group. 1,5-AG was significantly correlated to HbA1c in patients, but not controls. For patients with HbA1c < 8%, 1,5-AG demonstrated the widest range and was not predicted by HbA1c; 1,5-AG levels were narrowly distributed among patients with HbA1c ≥ 8%. Youth and young adults with T1D demonstrate similar 1,5-AG levels which are distinct from controls. 1,5-AG assessment may provide unique information beyond that provided by HbA1c in the mid-term assessment of glycemic control in young patients with T1D and HbA1c < 8%. © 2011 John Wiley & Sons A/S.