Hydrometers, Residual Sugar, and Water Kefir

[ggl3dde]

So for water kefir, I've been reading mixed information on how accurate you can get the sugar measurements to. I've made some wine and kombucha in the past, but now that I'm catering to a person with diabetes+candida, I want to be more precise.

Bar buying a spectrophotometer or sending a batch to a lab that owns one, how accurate can you get from using a hydrometer and urine test strips (e.g. Clinitest/Accuvin)?

From what I read, the urine strips are from .5% to 5% -- so would it be ideal to use a hydrometer to ~1sg then test with the strips?

But because water kefir is unique, would the hydrometer still be accurate with the alcohol content?

Or is there a more precise measuring method I should use?