A contact lens includes a glucose sensor which can determine when a detectable concentration of glucose is present in the optical fluids of the user. The glucose sensor can transition between a first state and a second state relative to the concentration of glucose within the optical fluid of the user. The glucose sensor can be bonded or otherwise attached or incorporated into the contact lens. While the contact lens is worn in the user's eye, either the user or another person can view the contact lens to quickly determine if an excessive amount of glucose is present in the user's system.
