Aims: To investigate early markers of long-term diabetic complications and the association to an extended glucose metabolic profile comprising glucose control (current and past), glucose variability and insulin sensitivity in children and adolescents with type 1 diabetes (T1D).

Background: Most Danish children and adolescents with T1D do not achieve their metabolic target and are at increased risk of developing long-term diabetic complications, reducing their life expectancy and increase their morbidity rate. Hence, improved metabolic control, a better understanding of what optimal metabolic control means, combined with detailed monitoring of the first markers of long-term complications and their reversibility or lack thereof are needed.

Methods: A prospectivel study of 400 children, aged 6-18 years old, with T1D\>12 months. Early markers of long-term diabetic complications will be investigated as arterial stiffness, nerve dysfunction and nephropathy. Data on T1D onset, duration, treatment modality, self-monitoring-blood-glucose profiles, growth, weight, and pubertal status will be collected. Blood sampling will include routine tests and markers of glucose, lipid, bone, and gastrointestinal metabolism. DXA-scan, Fibroscan, bone-age, eye-examination and physical activity will be measured. Data on retrospective glucose- and lipid-profiles will be collected. The children will be offered a followup every 5 years for the next two decades. Perspectives: This study provides novel insight into the frequency of early markers of long-term diabetic complications and its association to the interplay of the pancreas, adipose, gastrointestinal and bone metabolic axis. Which can assist in identifying subgroups of children and adolescents requiring earlier in-depth screening for early markers of long-term diabetic complications, for putative interventions for prevention, hence reducing morbidity and mortality in T1D.