No apparent local effect of insulin on microdialysis continuous glucose- monitoring measurements.

OBJECTIVE Data investigating the possible disturbing influence of insulin in the vicinity of continuous glucose monitoring (CGM) is lacking. We investigated the hypothesis that high local insulin concentrations would interfere with sensor readings. RESEARCH DESIGN AND METHODS Two microdialysis sensors were inserted in the periumbilical region of 10 continuous subcutaneous insulin infusion (CSII)-treated type 1 patients. A test sensor was inserted as close as possible to the insulin catheter and compared with a control sensor. Glucose peak and nadir were induced. Horizontal and vertical shifts were assessed using curve fitting, and mean absolute difference (MAD) between paired blood and sensor values were calculated. RESULTS Curve fitting showed no significant differences between the two sensors. MAD +/- SD was 8.50 +/- 3.47% for the test sensor and 9.21 +/- 3.17% for the control sensor, P = 0.72. CONCLUSIONS Microdialysis CGM can be accurately performed in the proximity of CSII systems.