Calibration of a Subcutaneous Amperometric Glucose Sensor Implanted for 7 Days in Diabetic Patients. Part 2. Superiority of the One-Point Calibration Method

Biosens Bioelectron. 2002 Aug;17(8):647-54. doi: 10.1016/s0956-5663(01)00304-9.

Abstract

Calibration, i.e. the transformation in real time of the signal I(t) generated by the glucose sensor at time t into an estimation of glucose concentration G(t), represents a key issue for the development of a continuous glucose monitoring system.

Objective: To compare two calibration procedures. In the one-point calibration, which assumes that I(o) is negligible, S is simply determined as the ratio I/G, and G(t) = I(t)/S. The two-point calibration consists in the determination of a sensor sensitivity S and of a background current I(o) by plotting two values of the sensor signal versus the concomitant blood glucose concentrations. The subsequent estimation of G(t) is given by G(t) = (I(t)-I(o))/S.

Research design and methods: A glucose sensor was implanted in the abdominal subcutaneous tissue of nine type 1 diabetic patients during 3 (n = 2) and 7 days (n = 7). The one-point calibration was performed a posteriori either once per day before breakfast, or twice per day before breakfast and dinner, or three times per day before each meal. The two-point calibration was performed each morning during breakfast.

Results: The percentages of points present in zones A and B of the Clarke Error Grid were significantly higher when the system was calibrated using the one-point calibration. Use of two one-point calibrations per day before meals was virtually as accurate as three one-point calibrations.

Conclusion: This study demonstrates the feasibility of a simple method for calibrating a continuous glucose monitoring system.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biosensing Techniques / instrumentation
  • Biosensing Techniques / statistics & numerical data*
  • Blood Glucose / analysis*
  • Blood Glucose Self-Monitoring / instrumentation*
  • Blood Glucose Self-Monitoring / methods
  • Blood Glucose Self-Monitoring / statistics & numerical data
  • Diabetes Mellitus, Type 1 / blood*
  • Humans
  • Prostheses and Implants

Substances

  • Blood Glucose