A biosensor structure based on a ternary photonic crystal (TPC) containing a defect is designed and simulated. This proposed biosensor detects the concentration of glucose in human urine. Based on the transfer matrix method, we theoretically studied the transmission spectra through the TPC presuming blood samples with different refractive indices (RIs) infiltrated into the defect layer of the proposed structures. By varying the concentration of glucose in the urine, the RI of the urine is changed, which in turn changes the sensor’s output response; both transmission response and resonance wavelength are affected. We evaluated average sensitivity (S) for the number of periods at different values N for optimization purposes. Our results show that the biosensor has performance parameters for a period value N = 6. Indeed, a value of 1033 nm of full width at half maximum photonic bandgap can be observed with a S of 965 nm / RIU. The quality factor is 1892.542 and the figure of merit is 756.86 RIU ^{− 1}. The proposed biosensor can be a miniaturized structure with extreme sensitivity in the concentration of glucose detection models