The detection of biochemical substances can be used for disease diagnosis or the assessment of treatment effectiveness. Nanocellulose, with its excellent biocompatibility, serves as an ideal material for flexible biosensors. Various nanocellulose-based flexible biosensors capable of detecting biochemical substances, such as glucose and urea present in sweat, have been developed. To improve enzyme immobilization efficiency and enhance sensing performance, cotton thread surfaces can be modified using Cellulose Nanofibrils (CNF). This system detects glucose and urea based on color changes resulting from enzymatic reactions and chromogenic reagent reactions. The sensor can be conveniently integrated into clothing, enabling simultaneous diagnosis of diabetes and renal failure, and achieving the purpose of real-time monitoring of human health status.