Can reversal of RYGB also reverse hypoglycemia?

An increasing number of patients affected by excess weight have turned to bariatric surgery for not only weight loss but also for improved metabolic health. This perspective is supported by recent data from controlled clinical trials highlighting the efficacy of bariatric surgery to resolve or improve obesity-related comorbidities including type 2 diabetes, hypertension, and dyslipidemia. However, long-term nutritional and metabolic complications require meticulous attention. One of the most challenging complications is post-bariatric hypoglycemia (PBH), a syndrome typically detected >1 year after surgery. In PBH, fasting glucose levels are normal, but shortly after eating, plasma glucose levels rapidly “spike”, with subsequent rapid declines in glucose, sometimes to hypoglycemic levels, within 1e3 h. The underlying pathophysiology of this condition is complex, and includes rapid gastric emptying, excessive postprandial secretion of incretin hormones such as GLP-1, increased insulin secretion, and reductions in counter regulatory hormone responses [1]. Remarkably, these and other changes in systemic metabolism ultimately result from surgically-induced alterations in gut anatomy and nutrient flow (Figure 1). Since current treatment approaches for PBH are not uniformly successful, Davis and colleagues now present results of a prospective case series of 6 patients in whom surgery was performed to reverse RYGB anatomy in order to treat severe PBH [2]. As a first step to determine whether reversal of anatomy would normalize meal-related hormonal and glycemic responses, a gastrostomy (G)-tube was placed in the excluded stomach, and a liquid mixed meal was administered via the G-tube. With this approach, nutrients would exit the remnant stomach via the pylorus and traverse the biliopancreatic limb, mixing with biliary and pancreatic secretions, yielding relative normalization of nutrient flow. Indeed, a prior report demonstrated that chronic G-tube feeding could be a successful treatment for PBH [3]. In the current study, participants having improvements in glucose profiles and no hypoglycemia with the test meal (delivered via the G-tube) were offered surgery, with 4 patients undergoing conversion to sleeve gastrectomy and 2 patients undergoing reversal to near-normal anatomy. Patients were followed for a mean of 20 15 months after revisional surgery. All reported improvement in severity of symptomatic hypoglycemia, with reduction in episodes from 19 to 2 per week. Moreover, post-meal glucose, insulin, and GLP-1 excursions were significantly diminished with both G-tube feeding and after reversal surgery. Not surprisingly, modest weight regain was observed, averaging 5 BMI units, but weight remained substantially