"Who are the companies that make SGLT2's? One of these companies would stand to benefit the most from some form of partnership or outright purchase."

Here's a quick list I compiled. Not all approved in US/EU. Some only Japan, etc.

Jardiance aka Empagliflozin (Lilly/Boehringer Ingelheim)

Farxiga aka Dapaglifloxin (Astrazeneca)

Invokana aka Canagliflozin (Johnson and Johnson)

Steglatro aka Ertugliflozin (Merck/Pfizer)

Zynquista aka Sotagliflozin aka LX4211 (Sanofi/Lexicon) dual SGLT2/SGLT2 inhibitor

Suglat aka Ipragliflozin (Astellas)

Apleway/Deberza aka Tofogliflozin (Sanofi/Kowa)

Lusefi aka Luseogliflozin (Taisho Pharmaceutical)

Remo/Remozen aka Remogliflozin (Kissei/Brighthaven Ventures LLC/Libbs Farmaceutica/Glenmark Pharmaceuticals)

Also a couple good resources on SGLT2s here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6028052/ 

https://diabetologia-journal.org/collections/sglt2-inhibitors/