Figure 1.

Bariatric surgery, including both RYGB and VSG, has widespread effects on glucose homeostasis. Early responses to surgery include a reduction in basal glucose and insulin levels (and consequently HOMA-IR) and a reduction in basal endogenous glucose production, as indicated in both human and rodent studies. Although unexplored in humans, rodents also demonstrate an early postoperative improvement in hepatic insulin sensitivity. Peak insulin levels in response to a meal are greater after surgery but then rapidly return to baseline. Last, and only after significant weight loss, peripheral insulin sensitivity and thus glucose uptake are increased. Red arrows, end points that are reduced; green arrows, end points that are increased.