This could be because someone has Glycosuria. Glycosuria is what happens when your kidneys can not take out enough sugar from your blood vessels and in turn passes it through urination. This is usually not a good thing to have as it could tell you that your kidneys do not function as good as they should. This is something that is not dangerous to your life, but does need to be looked at because it tells you that your kidneys are weaker than they should be and might lead to other complications later in life.