twerp said: I thought sugar content in urine goes up with diabetes.
It does. Diabetes basically means, in simplest terms, that your pancreas doesn't produce enough insulin, which is an enzyme which lowers the amount of glucose in your blood. As a result, diabetics have excess amounts in their blood and, yes, their urine.
So as the comic points out, Tomoyo's logic is bull. And as if it needs to be pointed out, don't drink urine, you sick bastards.