Diabetic Ketoacidosis (DKA): Although the patient has no history of diabetes, DKA can be the first presentation of diabetes. The presence of ketones in the urine supports this diagnosis. Urinary frequency is a common symptom due to the high glucose levels in the blood, leading to increased urine production. The white film in the urine could be due to the presence of ketones or possibly an infection, which can precipitate DKA.

Urinary Tract Infection (UTI): UTIs can cause urinary frequency and, in some cases, a visible change in urine appearance, such as a white film, especially if the infection involves the kidneys (pyelonephritis) or if there is a significant amount of pus in the urine.
Ketosis due to Low Carbohydrate Diet or Fasting: Individuals on a very low carbohydrate diet or those who are fasting can develop ketosis, leading to ketones in the urine. This could explain the urinary frequency if the patient is not adequately hydrated.
Dehydration: Severe dehydration can concentrate the urine, potentially leading to a visible change in appearance, and can also cause urinary frequency once fluids are replenished.

Septicemia or Sepsis: Although less likely, an infection severe enough to cause sepsis could present with urinary symptoms among many others. The presence of a white film in the urine could indicate a severe infection.
Kidney Stones: While kidney stones typically cause severe pain, they can also lead to urinary frequency and changes in urine appearance if there is an associated infection.

Hyperthyroidism: Can cause increased urine production leading to frequency, though it's less directly linked to a white film in the urine.
Adrenal Insufficiency: Certain forms, like Addison's disease, can lead to changes in urine production and potentially ketosis, though this would be a rare presentation.
Phenylketonuria (PKU): A genetic disorder that can lead to ketosis, though it's typically diagnosed in infancy and would be an unusual cause of new-onset symptoms in an adult without a previous diagnosis.