Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterised by a destruction of pancreatic β cells, which leads to absolute insulin deficiency. Persistently high glycaemia causes vascular damage throughout the body. Microvascular complications comprise the following: nephropathy, retinopathy, and neuropathy. Macrovascular complications include coronary heart disease (CHD), which may result in myocardial infarction, cerebrovascular disease (leading to strokes), and peripheral vascular disease. The pathogenesis of vascular complications is multifactorial and is probably the combination of direct glucose-mediated endothelial damage, oxidative stress, production of sorbitol, and advanced glycation end-products. Precise understanding of these mechanisms could help clinicians to identify diabetic complications earlier and subsequently implement indispensable therapy on time. It is vital to determine biomarkers of microvascular and macrovascular complications in children affected with T1DM. Advanced glycation end-products and their receptors, adhesive molecules, pro-and anti-inflammatory cytokines, enzymes such as N-acetyl-β-D-glucosaminidase, and growth factors are the subject of ongoing studies. Numerous biomarkers of diabetic microangiopathy are already known and may constitute therapeutic targets in the future. Unfortunately, despite substantial progress in the understanding of the processes by which microvascular and macrovascular complications develop, much effort still needs to be devoted to the matter, and further investigations are required.