The increased prevalence of Type I Diabetes (T1D) has also led to an increase in the number of macro-and microvascular complications of diabetes such as coronary heart disease, stroke, visual impairment, diabetic nephropathy (DN), and end stage renal disease (ESRD). Additionally, diabetes remains the most common reason for progressing to end stage renal disease.The aim of the study was to investigate the level of hypoxic disorders, condition of apoptosis controlling system and Vitamin D3 levels in children with diabetic nephropathy.The study involved 36 children with T1D and diabetic nephropathy (aged 6 to 17 years). The levels of the marker of cellular hypoxia HIF-1alfa, levels of the apoptotic factor caspase-3 studied by Western Blotting, Vitamin D3 levels were analyzed using ELISA assay.Stage-dependent manner of the cellular hypoxia and apoptotic effector caspase-3 levels increase documented. Both markers detected at significantly higher rate in DN patients as compared to T1D. Vitamin D3 deficiency documented in patients with DN.Thus, the development of DN in children is associated with the formation of cellular hypoxia and activation of apoptosis, as one of the basic mechanisms of kidney damage in DN. All mentioned above disorders accompanied by Vitamin D3 deficiency.