We demonstrate that P. copri is the dominant intestinal bacterial species in the GK non-obese model of polygenic type 2 diabetes, which is further stimulated by gastrectomy, and that its intestinal enrichment mimics the effects of bariatric surgery on both elevated circulating bile acids and stimulated expression of FXR to reduce glucose intolerance. The gene discussed is NR1H4; the disease is Glucose intolerance.