Do polyuria and polydipsia automatically make someone diabetic?

No. : Polyuria is the production of large amounts of dilute urine & polydipsia is elevated fluid intake; usually due to fluid losses from polyuria. These are just symptoms of a disorder & several different disease processes can cause this, with diabetes a common & important one. Diabetes is diagnosed by testing blood sugar levels. Other more rare causes are diabetes insipidus & psychogenic polydipsia.