The overall survival of acute lymphoblastic leukemia (ALL) and lymphoma in children and adolescents is above 90%. The survival rate has increased significantly during the last decades as a consequence of more intensive chemotherapy. This very toxic treatment results in severe acute toxicities and late effects, which is the biggest challenge today besides survival. The overall purpose of contemporary ALL treatment is to reduce the toxic treatment without compromising the excellent survival rates of these diseases. This study is a part of this. The researchers want to investigate the incidence of glucose intolerance and medicine induced diabetes during treatment for ALL and lymphoma with steroids (prednisolone or dexamethasone) and ± PEG-asparaginase. Steroids and asparaginase are used in the treatment of ALL and lymphomas, and both drugs may induce glucose intolerance or diabetes, especially when they are given concomitantly. The incidence and duration of increased blood glucose levels are not very well investigated, and especially not monitored continuously during treatment phases with steroids and +/- asparaginase, as the investigators want to do in this study. In the study the participants must have a glucose sensor attached under the skin, which continuously measures blood glucose during treatment. Moreover, blood samples are drawn several times to measure insulin sensitivity and beta cell function. The participants are children and adolescents (1.0-17.9 years) with newly diagnosed ALL or lymphoma treated at one of the four Danish pediatric oncology sites. Blood glucose levels are followed during treatment with steroids and PEG-asparaginase in these patient groups. The results may give rise to a new treatment guidelines for measuring and treating blood glucose in these patients. In the future this may help reduce the development of type 2 diabetes mellitus and metabolic syndrome in survivors of ALL and lymphoma.