The prevalence of type 1 diabetes (T1D) is increasing worldwide and is associated with significant microvessel complications, of which nephropathy, retinopathy and neuropathy are the most commonly studied. Although clinically evident microvascular complications of diabetes are rarely seen in childhood, early vascular abnormalities develop during childhood and accelerate during puberty. Vascular endothelial growth factor (VEGF) is a major mediator of angiogenesis, which is regulated by endothelial nitric oxide synthase (NOS3) at several levels. Together, VEGF and NOS3 play an important role in the pathogenesis of the microvascular complications of diabetes. Genetic variations in NOS3 and VEGF critically regulate endothelial survival and function and increase the susceptibility of patients to develop severe microvessel complications. Identification of the risk factors for and improved understanding of the subclinical signs of these diabetic microvascular complications will enable implementation of therapeutic strategies, potentially changing the course of vascular complications and improving the prognosis of children, adolescents and young adults with diabetes. Moreover, early detection of these variations may have a prognostic value or may suggest interventional approaches to regulate these proteins in patients with diabetes.