To evaluate whether frequent self-monitoring of blood glucose (SMBG) sufficiently reflects the true diurnal glucose control during ordinary daily life in type I diabetic patients.
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.
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 night (P < 0.05).
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.