The Global Diabetes Compact is a WHO-driven initiative uniting stakeholders around goals of reducing diabetes risk and ensuring that people with diabetes have equitable access to comprehensive, affordable care and prevention. In this report we describe the development and scientific basis for key health metrics, coverage, and treatment targets accompanying the Compact. We considered metrics across four domains: factors at a structural, system, or policy level; processes of care; behaviours and biomarkers such as glycated haemoglobin (HbA1c); and health events and outcomes; and three risk tiers (diagnosed diabetes, high risk, or whole population), and reviewed and prioritised them according to their health importance, modifiability, data availability, and global inequality.