Self-monitoring of blood glucose in type I diabetic patients: Comparison with continuous microdialysis measurements of glucose in subcutaneous adipose tissue during ordinary life conditions

OBJECTIVE - To evaluate whether frequent self-monitoring of blood glucose (SMBG) sufficiently reflects the true diurnal glucose control during ordinary daily life in type 1 diabetic patients. RESEARCH DESIGN AND METHODS - By using a microdialysis technique, continuous monitoring of adipose tissue glucose was performed in 24 type I diabetic patients during ambulatory conditions. A microdialysis probe was implanted subcutaneously and perfused by a portable microinfusion pump. Dialysate fractions were collected in 1- to 2-h samples during 3 consecutive days. The diurnal microdialysis glucose profiles were compared with those obtained by SMBG recordings performed seven times a day. RESULTS - In seven patients, the SMBG profiles showed marked aberrations as compared to the continuous microdialysis glucose recordings; during the 3-day study period, 5-6 inconsistencies were registered. In only 4 patients (17%) did SMBG provide a valid reflection (0-2 inconsistencies) of the diurnal glucose profile, whereas in 13 patients the SMBG recordings paralleled the diurnal adipose tissue glucose profiles in an intermediate way (3-4 major inconsistencies). The inaccuracy of the SMBG data was due more often to the fact that wide glucose swings remained unrecognized, rather than to erroneous testing techniques (P < 0.05), and it was more evident during the might (P < 0.05). CONCLUSIONS - In many type I diabetic patients, the true diurnal variability in glycemia is too great to be accurately reflected even by frequent self-monitoring of blood glucose.