In: Anatomy and Physiology
Polyuria (increased urination) and polydypsia (increased thirst) are two signs of diabetes and this is the link between diagnosis of gestational diabetes and the patient's signs of polyuria and polydypsia.
During pregnancy, placenta makes hormones that causes glucose to build up in blood and pancreas on the other side secretes insulin to counter the effect of hormones. But if pancreas cannot produce enough insulin or to stop glucose using insulin, the blood glucose level goes up leading to gestational diabetes.
Uncontrolled diabetes mellitus causes increased glucose to be excreted via urine. This causes osmotic diuresis as water follows the increased glucose concentration in urine leading to abnormally high urine output.
Polydypsia is an early symptom of diabetes mellitus. Increased glucose in blood causes blood osmolarity to increase which stimulates osmoreceptors in thirst center of hypothalamus and causes increased thirst.