| CPC A61M 5/1723 (2013.01) [A61M 5/142 (2013.01)] | 14 Claims |

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1. A method comprising:
(a) inserting an insulin delivery device subcutaneously into a body of a subject,
wherein said insulin delivery device comprises an amperometric glucose sensor comprising an electrode layer comprising at least one indicating electrode, wherein said electrode layer underlies a redox-catalytic layer comprising a redox mediator;
(b) using said insulin delivery device to deliver an insulin or insulin analog formulation subcutaneously to said subject,
wherein said insulin or insulin analog formulation comprises an excipient comprising a phenol or cresol,
wherein said insulin delivery device comprises a hollow tube comprising a proximal end and a distal end, wherein said proximal end is in fluid communication with a source of said insulin or insulin analog formulation; and
(c) using said amperometric glucose sensor to measure a subcutaneous glucose concentration in said body of said subject,
wherein said measuring comprises using said redox-catalytic layer to allow electron transfer from subcutaneous glucose to said at least one indicating electrode sufficient to cause a response of said amperometric glucose sensor to said subcutaneous glucose concentration at an applied bias potential of no more than +250 millivolts (mV) relative to a reference electrode,
wherein (b) and (c) are performed at the same time for a time period of at least one hour subsequent to said positioning in (a), while maintaining a sensitivity of said sensor of at least 50% of an initial sensitivity of said sensor up to one hour subsequent to said positioning in (a).
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