Can cancer cause glucose in urine or high blood sugar?

No, it would be unus: Cancer by itself does not affect the blood glucose, so it is not the likely cause of sugar in urine or high blood sugar. But coincidental Diabetes can occur, so it should not surprise you as Diabetes is fairly common disease. On rare occasions Cancer of the Pancreas can preceed recent onset of diabetes. This association should be kept in mind in cases of newly diagnosed Diabetes.