One of the components of a health system as defined by the World Health Organization (WHO) is data that the health system collects, generates, and uses to improve the health of its population. The aim of this paper is to describe key lessons from Denmark in planning, implementing, and using health system-generated data, using Type 1 diabetes as a tracer. A broad literature search was complemented with a review of grey literature, two series of interviews with Danish experts, and feedback from a presentation of these findings to two expert meetings. Denmark, through its unique identifier and data environment, enables the health system to collect a variety of data on Type 1 diabetes. Facilitators and challenges exist for data collection, data aggregation, use of data, communication of data and results, and intangible factors. For each of these, the environment, infrastructure, health system, and Danish society act as facilitators. Barriers relate to data being collected primarily for clinical and administrative purposes, and not necessarily for research, planning, policymaking, or advocacy. Fora are lacking to facilitate the communication and presentation of these results. An intangible element is the trust Danes have in their system, which is hard to replicate. As shown in the Danish setting, contextual factors cannot be negated in developing and implementing data-related solutions at a population level. The lessons from Denmark show that there is the need to conceive and act on all aspects of the data from its collection, aggregation, use, and communication. The last step of interaction between science and policy and practice requires a range of factors, including networks and knowledge brokers.