The hyperglycemia of diabetes mellitus causes an osmotic diuresis

, leading to large deficits of water, sodium and potassium during acute loss of control, e.g., diabetic ketoacidosis. An osmotic diuresis may also result from excessive urea production owing to excessive protein administration.

What causes excessive diuresis?

Causes. The most common cause of polyuria in both adults and children is uncontrolled diabetes mellitus, which causes osmotic diuresis, when glucose levels are so high that glucose is excreted in the urine. Water follows the glucose concentration passively, leading to abnormally high urine output.

Does diabetes affect urine flow?

Diabetes can also impair the relaxation of the internal urethral sphincter (urethral smooth muscle), which also affects the flow of urine out. The bladder can also become overactive: the damaged nerves can send wrong signals to the bladder, making it squeeze and expel fluids without warning.