Method of determining analyte level using subcutaneous electrode

Abstract

A small diameter flexible electrode designed for subcutaneous in vivo amperometric monitoring of glucose is described. The electrode is designed to allow “one-point” in vivo calibration, i.e., to have zero output current at zero glucose concentration, even in the presence of other electroreactive species of serum or blood. The electrode is preferably three or four-layered, with the layers serially deposited within a recess upon the tip of a polyamide insulated gold wire. A first glucose concentration-to-current transducing layer is overcoated with an electrically insulating and glucose flux limiting layer (second layer) on which, optionally, an immobilized interference-eliminating horseradish peroxidase based film is deposited (third layer). An outer (fourth) layer is biocompatible.

1 . (canceled)  
   
   
       2 . A method comprising: 
 (a) subcutaneously positing at least a portion of a first sensor in a patient;    (b) obtaining a first sensor reading from the first sensor related to an analyte level;    (c) obtaining a second sensor reading from a second sensor, the second sensor reading related to the analyte level;    (d) calibrating the first sensor using the second sensor reading.    
   
   
       3 . The method of  claim 2 , wherein the step of obtaining a second sensor reading from a second sensor comprises: 
 (a) withdrawing a sample of blood from the patient; and    (b) obtaining the analyte level in the sample of blood with the second sensor.    
   
   
       4 . The method of  claim 3 , wherein the step of withdrawing a sample of blood comprises withdrawing only a single sample of blood.  
   
   
       5 . The method of  claim 2 , wherein the analyte is glucose.  
   
   
       6 . The method of  claim 2 , wherein the step of obtaining a second sensor reading from a second sensor comprises: 
 (a) obtaining the second sensor reading from the second sensor after at least one hour of operation of the first sensor.    
   
   
       7 . The method of  claim 6 , further comprising: 
 (a) obtaining a third sensor reading from a third sensor, the third sensor reading related to the analyte level; and    (b) calibrating the first sensor using the third sensor reading.    
   
   
       8 . The method of  claim 7 , wherein the step of obtaining a third sensor reading from a third sensor comprises: 
 (a) withdrawing a sample of blood from the patient; and    (b) obtaining the analyte level in the sample of blood with the third sensor.    
   
   
       9 . The method of  claim 8 , wherein the step of obtaining a third sensor reading from the third sensor comprises: 
 (a) obtaining the third sensor reading from the third sensor after 72 hours of operation of the first sensor.    
   
   
       10 . The method of  claim 2 , wherein the step of subcutaneously positioning at least a portion of the first sensor in a patient comprises: 
 (a) subcutaneously positioning at least a portion of the first sensor in an abdomen, inner thigh, or arm of the patient.    
   
   
       11 . The method of  claim 2 , wherein the second sensor is a subcutaneously implanted sensor.  
   
   
       12 . A method comprising: 
 (a) subcutaneously positioning at least a portion of a first sensor in a patient;    (b) obtaining a first sensor reading from the first sensor related to an analyte level;    (c) obtaining a second sensor reading from a second sensor, the second sensor reading related to the analyte level;    (d) confirming the results of the first sensor reading with the second sensor reading.    
   
   
       13 . The method of  claim 12 , wherein the step of obtaining a second sensor reading from a second sensor comprises: 
 (a) withdrawing a sample of blood from the patient; and    (b) obtaining the analyte level in the sample of blood with the second sensor.    
   
   
       14 . The method of  claim 13 , wherein the step of withdrawing a sample of blood comprises withdrawing only a single sample of blood.  
   
   
       15 . The method of  claim 12 , wherein the analyte is glucose.  
   
   
       16 . The method of  claim 12 , wherein the step of obtaining a second sensor reading from a second sensor comprises: 
 (a) obtaining the second sensor reading from the second sensor after at least one hour of operation of the first sensor.    
   
   
       17 . The method of  claim 12 , further comprising: 
 (a) obtaining a third sensor reading from a third sensor, the third sensor reading related to the analyte level; and    (b) confirming the results of the first sensor using the third sensor reading.    
   
   
       18 . The method of  claim 17 , wherein the step of obtaining a third sensor reading from a third sensor comprises: 
 (a) withdrawing a sample of blood from the patient;    (b) obtaining the analyte level in the sample of blood with the third sensor.    
   
   
       19 . The method of  claim 17 , wherein the step of obtaining a third sensor reading from the third sensor comprises: 
 (a) obtaining the third sensor reading from the third sensor after 72 hours of operation of the first sensor.    
   
   
       20 . The method of  claim 12 , wherein the step of subcutaneously positioning at least a portion of the first sensor in a patient comprises: 
 (a) subcutaneously positioning at least a portion of the first sensor in an abdomen, inner thigh, or arm of the patient.    
   
   
       21 . A method comprising: 
 (a) subcutaneously positioning at least a portion of a first sensor in a patient; and    (b) calibrating the first sensor after at least 1 hour of subcutaneously positioning the first sensor.    
   
   
       22 . The method of  claim 21 , wherein the step of calibrating comprises: 
 (a) using a second sensor.    
   
   
       23 . The method of  claim 22 , wherein the step of calibrating further comprises 
 (a) using a third sensor.    
   
   
       24 . The method of  claim 21 , wherein the step of calibrating the first sensor after at least 1 hour comprises: 
 (a) calibrating the fist sensor periodically after at least 1 hour.    
   
   
       25 . The method of  claim 21 , wherein the step of subcutaneously positioning at least a portion of the first sensor in a patient comprises: 
 (a) subcutaneously positioning at least a portion of the first sensor in an abdomen, inner thigh, or arm of the patient.