Noneffect of oral urinary copper ascorbic acid on reduction glucose test

References and texts in the fields of diabetes and clinical chemistry commonly report that ascorbic acid when given orally or parenterally gives a false-positive reaction to the copper reduction glucose test (Clinitest). This impression is based on a study in which ascorbic acid (250 mg./dl.) was added to urine in vitro, with a resultant positive-test reading in the absence of glucose. Ascorbic acid is a reducing agent, and theoretically it could interfere with the copper reduction method of glucose detection. In the current study 10 nondiabetic men were ingesting 4 and 6 gm. ascorbic acid per day. A total of 360 glucose detection tests with the copper reduction method were undertaken. In no instance was there a positive reaction to the glucose test.