When your glucose rises above 180 mg/dl (10.0 mmol/L), glucose begins to spill into the urine and make it sweet. Up to that point, the kidney, the filter for the blood, is able to extract the glucose before it enters your urine.
Frequent urination and thirst:
The glucose in the urine draws more water out of your blood, so more urine forms. More urine in your bladder makes you feel the need to urinate more frequently, day and night. As the amount of water in your blood declines, you feel thirsty and drink much more frequently.
Without sufficient insulin, or if the insulin is not effective, glucose can’t enter cells (such as muscle and fat cells) that depend on insulin