Potential pitfalls in the use of Glucoscan and Glucoscan II meters for self-monitoring of blood glucose.

We discovered that skilled nurses only casually trained in the use of a fingertip blood glucose reflectance meter (Glucoscan, Lifescan, Mountainview, California) had a 36% incidence of unacceptable results (greater than 15% from reference). A controlled study was undertaken and showed that with Glucoscan I (GI) 4 of 27 readings were unacceptable and with Glucoscan II (GII) 3 of 27 readings were unacceptable, a statistically nonsignificant difference. Minor deviations from the manufacturer's recommended technique had a significant effect on the results with GI. In contrast, GII was much less sensitive to variations in recommended technique. GI underestimated the reference glucose concentration by 11.7%, and GII overestimated by 6.5%, a statistically significant difference. We conclude that the health professional must be aware of interdevice and intradevice variability in self-monitoring of blood glucose (SMBG). Patients need careful training in the method of SMBG. The results of any single value should be interpreted with caution.