In people with diabetes, polydipsia is caused by increased blood glucose levels. When blood glucose levels get high, your kidneys produce more urine in an effort to remove the extra glucose from your body. Meanwhile, because your body is losing fluids, your brain tells you to drink more in order to replace them.

Why does DKA cause increased thirst?

Excessive thirst and increased urination

Your kidneys are forced to work overtime to filter and absorb the excess glucose. When your kidneys can't keep up, the excess glucose is excreted into your urine, dragging along fluids from your tissues, which makes you dehydrated. This will usually leave you feeling thirsty.

Why does DKA cause dehydration?

The buildup of ketones causes the blood to become more acidic. The high levels of blood glucose in DKA cause the kidneys to excrete glucose and water, leading to dehydration and imbalances in body electrolyte levels.