It is important to be aware that the intake of significant does of Vitamin C---no one knows exactly how much---is capable of interfering with common tests for glucose, (sugar), in the urine Specifically the TES_TAPE™ and the CLINITEST™ dip sticks can both be incorrectly read as negative because of the interference of Vitamin C in the urine. CLINITEST™ tablets can give a false positive reading. For this reason, we recommend that our patients use the DIASTIX™, manufactured by Ames Company, which will only miss an occasional “trace” of sugar.