Gut microbiota of patients with type 2 diabetes and gastrointestinal intolerance to metformin differs in composition and functionality from tolerant patients.

Objective: Metformin modifies the gut microbiome in type 2 diabetes and gastrointestinal tolerance to metformin could be mediated by the gut microbiome.

Methods: We enrolled 35 patients with type 2 diabetes not receiving treatment with metformin due to suspected gastrointestinal intolerance. Metformin was reintroduced at 425 mg, increasing 425 mg every two weeks until reaching 1700 mg per day.