<p>Conventional methods of blood glucose monitoring typically require finger pricking to obtain a blood sample, which can be both painful and uncomfortable. Additionally, environmental factors can impact the accuracy and performance of glucose meters and test strips of diabetic patients. We introduce a novel non-invasive lab-on-chip device with an ultra-high sensitivity for routine blood sugar monitoring in diabetic patients, utilizing a patient's tear instead of blood samples to avoid daily unpleasant tests. The proposed sensor leverages the ultra-high sensitivity of the Mach–Zehnder interferometer and the linear response of the Microring resonator, which takes advantage of hybrid single and double-slot optimized waveguides. By employing the delay line signal approach and the Z-transform, a formula was developed to survey the system's overall transmittance. The results were simulated using the variational FDTD method, and an ultra-high sensitivity of 1092 nm/RIU with a high detection precision of 1.8 × 10⁻⁵ RIU was achieved using varFDTD simulation for the sensor. Results simulated for various concentrations of tears and can rapidly differentiate between diabetic and normal tears. The proposed sensor has various advantages, including a quick and painless detection procedure, high precision, and a wide performance range, all of which are desirable in an ideal lab-on-a-chip device.</p>