Continuous glucose monitoring in subjects with type 1 diabetes: improvement in accuracy by correcting for background current.
BACKGROUND
A cause of suboptimal accuracy in amperometric glucose sensors is the presence of a background current (current produced in the absence of glucose) that is not accounted for. We hypothesized that a mathematical correction for the estimated background current of a commercially available sensor would lead to greater accuracy compared to a situation in which we assumed the background current to be zero. We also tested whether increasing the frequency of sensor calibration would improve sensor accuracy.


METHODS
This report includes analysis of 20 sensor datasets from seven human subjects with type 1 diabetes. Data were divided into a training set for algorithm development and a validation set on which the algorithm was tested. A range of potential background currents was tested.


RESULTS
Use of the background current correction of 4 nA led to a substantial improvement in accuracy (improvement of absolute relative difference or absolute difference of 3.5-5.5 units). An increase in calibration frequency led to a modest accuracy improvement, with an optimum at every 4 h.


CONCLUSIONS
Compared to no correction, a correction for the estimated background current of a commercially available glucose sensor led to greater accuracy and better detection of hypoglycemia and hyperglycemia. The accuracy-optimizing scheme presented here can be implemented in real time.
El Youssef
Joseph
J
Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
Castle
Jessica R
JR
Engle
Julia M
JM
Massoud
Ryan G
RG
Ward
W Kenneth
WK
D000328:Adult; D000465:Algorithms; D001185:Artificial Intelligence; D015374:Biosensing Techniques; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000379:methods*; D002138:Calibration; D003627:Data Interpretation, Statistical; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D005260:Female; D005934:Glucagon / Q000008:administration & dosage / Q000627:therapeutic use; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000175:diagnosis; D007003:Hypoglycemia / Q000097:blood / Q000175:diagnosis; D007332:Insulin Infusion Systems; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D012015:Reference Standards; D015203:Reproducibility of Results
D001786:Blood Glucose; D005934:Glucagon; D006442:Glycated Hemoglobin