Mich. Comp. Laws § 338.3661a
A record or portion of a record, material, information, or other data received, prepared, used, or retained by the department or commission under this act that includes a trade secret or commercial, financial, or proprietary information of a licensee or license applicant, and that the licensee or applicant requests in writing be treated as confidential by the department or commission, is not subject to the freedom of information act, 1976 PA 442, MCL 15.231 to 15.246. As used in this section, "trade secret or commercial, financial, or proprietary information" means information that has not been publicly disseminated or that is unavailable from other sources, the release of which might cause the licensee or applicant significant competitive harm.
MCL 338.3661a