Utilize the input text as a context reference, choose the right relationship between 'beta cell' and 'insulin' from the options.
Options: developer, parent organization, product/material produced, founded by

No new safety signals or data were presented at this year's ADA conference, but data was presented that confirmed the preservation and restoration of beta cell function as determined by C-peptide, which is a measure of a person's own insulin production.
product/material produced