A Study of Brenipatide (LY3537031) in Participants With Irritable Bowel Syndrome-Diarrhea (IBS-D)

The purpose of this study is to evaluate how well brenipatide (LY3537031) is tolerated, what side effects may occur, and the safety and efficacy in participants with Irritable Bowel Syndrome-Diarrhea (IBS-D). The study drug will be administered subcutaneously (SC) (under the skin) when compared with placebo. The study will last approximately 35 weeks.

Inclusion Criteria: * Meet Rome IV criteria for IBS-D, which includes having greater than 25% of bowel movements with Bristol Stool Form Scale (BSFS) Types 6 or 7 and \<25% of bowel movements with BSFS Types 1 or 2 * Based on the daily eDiary collection during the screening period: * Have average of worst abdominal pain score of ≥3.0 on a 0-to-10-point scale during the 14 consecutive days prior to randomization * Have at least 4 days per week with a maximum BSFS ≥5 AND with at least 2 days of the 4 days per week with a maximum BSFS ≥6 during the 14 consecutive days prior to randomization * Have had no major changes in diet in the 4 weeks prior to screening Exclusion Criteria: * Have a diagnosis of IBS with a subtype of constipation, mixed IBS, or unclassified IBS by the Rome IV criteria * Have a history of inflammatory or immune-mediated gastrointestinal disorders * Have a known clinically significant gastric emptying abnormality