Diabetic ketoacidosis (DKA) is a severe complication of type 1 diabetes (T1D) that can have life-threatening consequences. It occurs when there is a high level of glucose in the blood and the body produces excessive amounts of ketone bodies. To manage this condition, individuals with T1D need to constantly monitor their levels of ketone bodies and glucose. While continuous glucose monitoring (CGM) devices have made significant advancements in providing non-invasive or minimally invasive glucose measurements, there has been little progress in developing methods for continuous monitoring of ketone bodies (CKM). Currently, the commonly used approaches involve self monitoring with commercially available blood or urine strips. However, these tools have limited adoption, provide only single time point measurements, and can be costly for some patients. In our project, which is funded by Breakthrough T1D (2-SRA-2022-1167-M-B), we address this challenge by utilizing a minimally invasive biosensor based on hydrogel microneedle (HMN). This biosensor enables simultaneous and continuous measurement of the primary biomarker for ketone formation, 3-β hydroxybutyrate (β-HB), as well as glucose levels. By doing so, we intend to reduce the risk of diabetic ketoacidosis in patients with T1D. We plan to test the developed CGM-CKM device on human subjects, including both healthy volunteers (HV) and patients with T1D. The HV testing will take place at the laboratory of Dr. Poudineh and Dr. Devries-Aboud in Waterloo, while the validation involving patients with T1D will be conducted in collaboration with Dr. Lal at Stanford.