Objective: There is still controversy over the impact of diabetes mellitus (DM) on bone mass in children. Pyridinoline (Pyr) and deoxypyridinoline (DPyr), which stabilize the collagen chains within the extracellular matrix, are known as specific bone turnover markers. The aim of this study was to investigate the relationship between urinary Pyr and DPyr excretions and bone mineral density (BMD) in children with type 1 DM. Methods: Serum levels of Ca, phosphorus (P), magnesium (Mg), and parathormone (PTH), alkaline phosphatase (ALP) activity, and urinary excretions of Pyr and DPyr were evaluated in 50 diabetic and 130 healthy control subjects aged between 7 and 15 years. The BMD was measured using DEXA at the lumbar vertebrae 2-4. Results: Serum levels of Ca, P and PTH, and BMD were similar between the two groups (p > 0.05). The serum ALP activity was significantly higher in diabetics than in healthy subjects (257.7 +/- 86.5 vs. 188.2 +/- 61.8, p < 0.05, respectively). Both urinary Pyr and DPyr excretions were significantly higher in diabetic subjects compared to control subjects (127.4 +/- 95.5 vs. 88.7 +/- 63.7, p < 0.05, respectively, and 23.6 +/- 12.7 vs. 17.2 +/- 9.6, p < 0.05, respectively). The urinary excretions of Pyr and DPyr were similar in male and female subjects within both groups. Conclusion: The urinary excretions of Pyr and DPyr are higher in diabetic subjects than in healthy controls, suggesting the presence of increased bone turnover in diabetic patients, but we could not observe any negative effect of childhood diabetes on BMD. These results may suggest that diabetic patients are at risk for a decreased peak bone mass.