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The metalloprotein observation is a genomic annotation, not a measured metal interaction.\nexposure: Metformin or placebo for 4 months in treatment-naive type 2 diabetes\nevidence_span: {\"source_cache\": \"artifacts/metformin-research/28530702.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"885eedb24772fbd218ff6497da6c39f486d0e0b0293ddd97e8fd7b3f23330b11\", \"start_char\": 0, \"end_char\": 1137, \"text_sha256\": \"885eedb24772fbd218ff6497da6c39f486d0e0b0293ddd97e8fd7b3f23330b11\"}\n[metformin-p28530702] Metformin alters the gut microbiome of individuals with treatment-naive type 2 diabetes, contributing to the therapeutic effects of the drug. 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