To assess the realibility of delayed readings of the reactive strips for glycemia BM-test 20-8, obtained by patients at their home and read in the health center both according to the Boehringer color scale and by reflectometer Reflolux II, we assessed 100 strips. One half were stored in opaque tubes and the rest were exposed to the light, all at room temperature. They were read both visually and with reflectometer Reflolux II in a programmed fashion on the days 0, 1, 3, 5, 7, 10 and 14. The results showed that the accuracy of the color scale as compared with the reflectometer depended on the levels of glycemia (owing to the scale intervals), without significant differences. Regarding the delayed reading in the strips kept away from light, there was a statistically significant reduction of 7 mg/dl on the third day. According to the regression analysis, the strips lose 2 mg/dl each day. In the strips exposed to the light, the measurement loss on the 14th day is significantly greater than in strips removed from light.