With the increasing population of diabetic patients worldwide, it is crucial to detect various diabetic complications timely, efficiently and conveniently for large-scale screening at low cost. However, the conventional blood glucose testing does not provide the progress status of diabetic chronic complications such as diabetic retinopathy (DR) for non-intrusive diabetic care. By developing new approaches to hierarchical retinal image analysis and lossless data embedding associated with a high-performance fundus camera, we have invented a computer aided detection (CAD) system to achieve non-intrusive DR screening and monitoring with privacy protection. The comprehensive performance assessment of our prototype demonstrates its feasibility for effective diabetic care with wide applications and excellent potentials.