OP links to a 2014 study, but recent research as of 2022 continues to show promise. Pretty cool.

https://www.salk.edu/news-release/salk-researchers-find-a-new-route-for-regulating-blood-sugar-levels-independent-of-insulin/

“Previously, the lab showed that injecting FGF1 dramatically lowered blood glucose in mice and that chronic FGF1 treatment relieved insulin resistance. But how it worked remained a mystery.

In the current work, the team investigated the mechanisms behind these phenomena and how they were linked. First, they showed that FGF1 suppresses lipolysis, as insulin does. Then they showed that FGF1 regulates the production of glucose in the liver, as insulin does. These similarities led the group to wonder if FGF1 and insulin use the same signaling (communication) pathways to regulate blood glucose.”

In mice.