Diabetes is a disease that makes it difficult for a person's body to regulate blood sugar. An early symptom can be frequent urination. What might explain this? Blood glucose is so abnormally high that all of the sugar cannot be reabsorbed, which also leads to lower reabsorption of water. Sugar crystals form in the glomerulus and prevent filtration. The body uses lots and lots of water to flush out all the extra sugar. The kidney must overproduce urine to maintain the same sugar concentration as found in the blood.