Glycosuria or glucosuria is the excretion of glucose into the urine. Ordinarily, urine contains no glucose because the kidneys are able to reclaim all of the filtered glucose back into the bloodstream. Glycosuria is nearly always caused by elevated blood glucose levels, most commonly due to untreated diabetes mellitus. When the blood glucose level exceeds about 160 - 180 mg/dl (8.9 - 10 mmol/l), the kidneys become overwhelmed and begin to excrete glucose in the urine. Therefore, patients with GOOD diabetes control should NOT have glucose in their urine.

the body releases everything it does not metabolize in the urine. Diabetics have high levels of sugar in their system unless they are reguarly taking a dose of insulin. when those levels get high, sugar will be released in the urine.

generally insulin helps in the conversion of glucose into glycogen which is then stored in the liver. In people who have diabetes insulin is not produced hence the excess glucose in the blood stream is removed by the kidneys in urine