The rise of single-use electronics for fast health screening has prompted a reevaluation of traditional materials and manufacturing techniques to address the growing issue of electronic waste (e-waste). Inexpensive self-monitoring devices provide valuable insights into the body's essential metabolic functions. They can measure outrange values in key diseases, e.g. hyper- or hypoglycemia in diabetes. Currently, the prevalent use of non-degradable substrates and toxic metals in glycemia tests significantly contributes to plastic and electronic waste. In this work, we propose an affordable and environmentally friendly glucose monitoring device printed on a bio-based and biocompatible substrate made of agar derived from red algae. The electrodes for the enzymatic electrochemical detection of glucose are composed of a carbon-based material, while the biorecognition element comprises of the enzyme glucose oxidase coupled with an electron mediator. The device demonstrated the electrochemical detection of physiological levels of glucose in the linear detection range of 1–15 mM, sufficient for accurately monitoring glucose level in patients’ blood. Additionally, this glucose sensor exhibits a low interference from other electroactive species usually present in human tissues, including blood. This all-carbon electrode sensor manufactured on our bio-sourced substrate aids the development of the next generation, metal-free, eco-friendly devices for healthcare monitoring.