What Duolingo score do you need for University of Glasgow?

The programme pages say tests must have been taken within 2 years 5 months of the programme start date, and the requirement must be met in a single test.

A degree from a majority English-speaking country, as defined by UKVI and including Canada if taught in English, can replace a test if you studied at least your final undergraduate year or 9 months at master's level there and finished within 6 years of the start date.

For comparison, the MSc Management page asks for IELTS 6.5 with no subtest below 6.0 where it asks for Duolingo 120.

Glasgow accepts its own English for Academic Study pre-sessional courses as evidence, with direct entry for successful students and results valid for 2 years after completion. It also lists pre-sessional courses at other BALEAP-accredited universities, including Edinburgh, Durham, Reading and UCL.

Requirements vary by programme and change between admissions cycles. The score that binds you is the one on your Glasgow programme page and in your offer letter, so check it there before you book a test.