Background The aim of the study is to identify the effect of salt intake and diabetes itself on blood pressure (BP) profile and microalbuminuria in children with type one diabetes mellitus (T1DM). Our hypothesis is that higher amount of salt consumption and/or hyperglycemia may impair blood pressure pattern in children with T1DM. Methods This cross-sectional study included 84 children and adolescents with T1DM (62% females, age 13.9 +/- 3.2 years, disease duration 7.3 +/- 3.1 years, 43% poorly controlled diabetes) and 54 aged- and sex-matched healthy children with an adequately collected 24-h urine samples. Urine sodium, creatinine, and microalbumin were measured and salt intake was assessed on the basis of sodium excretion in 24-h urine. Blood pressure profile of the children with T1DM was evaluated with 24-h ambulatory blood pressure monitoring. Results Compared to the children with well-controlled diabetes, children with poorly controlled diabetes had significantly higher standard deviation scores (SDS) of nighttime systolic BP (0.22 +/- 1.28 vs - 0.87 +/- 0.76, p = 0.003) and lower dipping in diastole (13.4 +/- 5.9 vs 18.4 +/- 8.1, p = 0.046). Among T1DM group, children with the highest quartile of salt intake had higher nighttime systolic and diastolic BP-SDS (0.53 +/- 1.25 vs - 0.55 +/- 0.73, p = 0.002 and 0.89 +/- 1.19 vs 0.25 +/- 0.63, p = 0.038, respectively) and lower dipping in systole compared to their counterparts (7.7 +/- 5.0 vs 11.5 +/- 6.1, p = 0.040). High averaged HbA1c was independently associated with higher both daytime and nighttime systolic BP-SDS (p = 0.010, p < 0.001) and nighttime diastolic BP-SDS (p = 0.001), and lower diastolic dipping (p = 0.001). High salt intake was independently associated with higher nighttime systolic BP-SDS (p = 0.002) and lower systolic dipping (p = 0.019). A 24-h MAP-SDS was the only independent risk factor for microalbuminuria (p = 0.035). Conclusion Beside poor diabetic control, high salt consumption appears to be an important modifiable risk factor for impaired BP pattern, which contributes to the development of diabetic kidney disease in children with T1DM.