A higher abundance of each of seven types of butyrate-producing bacteria — Christensenellaceae, Christensenellaceae R7 group, Marvinbryantia, Ruminococcaceae UCG005, Ruminococcaceae UCG008, Ruminococcaceae UCG010, and Ruminococcaceae NK4A214 group — was associated with lower insulin resistance, after adjusting for confounders such as diet and medications (all P < .001).