Out of curiosity I've applied (common household) sugar + water mixture to a urine glucose test strip and found no change in color. Is the test strip faulty? Is there any other way to confirm that the test strip works?
According to Cowart and Stachura (1990 NBK 245):
Techniques for measuring glucosuria are based upon either glucose oxidase (specific for glucose) or copper sulfate reduction (nonspecific: detects reducing substances including glucose, fructose, lactose, pentoses, galactose, homogentisic acid, and ascorbic acid). ... In the glucose oxidase-based technique, hydrogen peroxide is generated and reacts with horseradish peroxidase to produce nascent oxygen. It in turn oxidizes orthotoluidine to produce the blue or purple color that is read. In [some reactions], oxidized orthotoluidine is reacted with the yellow dye tartrazine to produce a greater range of color development
Regardless, it seems unwise to attempt to mix up a positive control for your medical test equipment from table sugar.
If necessary, use positive controls from vendors with traceable lot numbers and material safety data sheets. For example, this product includes positive controls for glucose (I have no affiliation with the company and cannot confirm it actually works).