Electrochemical sensors for determination of analyte concentrations in fluids for medical purposes; sensors for medical use to gather analyte concentration data; medical device for monitoring and providing information related to analyte concentrations; medical diagnostic apparatus for determination of analyte concentrations; medical apparatus for monitoring analyte concentrations in interstitial fluid; wearable sensors used to measure and provide information related to analyte concentrations in interstitial fluid, all for medical purposes; patient monitoring sensors for monitoring analyte concentrations, all for medical purposes; patient monitoring sensors for determination of analyte concentrations in interstitial fluid, all for medical purposes