All there’s to know about diabetes and how to beat it

[GoldfishLord]

World Health Day: All there’s to know about diabetes and how to beat it

(Reference: https://www.hindustantimes.com/heal...-to-beat-it/story-gFhDg7ekoqSqvkRiGFuclN.html )
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I'm having trouble understanding the role of "to".
I'd be most grateful if you could let me know about it.

 

[Phaedrus]

The "to" occurs inside a relative clause modifying "All": "[that] there is __ to know about diabetes."

If you have something to eat in your refrigerator, you have something in it which can be eaten.

If there is something to know about diabetes, there is something which can be known about it.

P.S. Hindustan Times's use of "there's" there is ungrammatical. It must be written "there is," without contraction. The explanation for this type of ungrammaticality with the contraction of "be" is controversial. One explanation is that it has something to do with the fact that a site of deletion or movement follows "be." This type of ungrammaticality is not restricted to relative clauses. The problem can arise, e.g., in embedded questions: "He doesn't know what there's to know about diabetes."

 

[Tdol]

The explanation for this type of ungrammaticality with the contraction of "be" is controversial.

But there is is still right whatever the controversy.

 

[jutfrank]

But there is is still right whatever the controversy.

Phaedrus didn't mean there's a controversy as to whether the contraction is grammatical (it isn't). The controversy is over why it's ungrammatical.