Diabetes improvement following Roux-en-Y gastric bypass: understanding dynamic changes in insulin secretion and action.

Abstract

Roux-en-Y gastric bypass (RYGB) surgery leads to substantial and sustained weight loss and improved cardiometabolic parameters in obese people (1). Approximately 80% of patients with type 2 diabetes (T2D) experience complete remission, defined as normoglycemia without medication, and another 15% have improvement, albeit remaining on medication (2). These rates are superior to those seen with conventional medical management (3–5). Several lines of evidence suggest such glycemic improvements are beyond those anticipated by weight loss alone. For many, remission of diabetes occurs within days, before significant weight loss (6,7). Moreover, diabetes remission does not occur with similar degrees of caloric reduction following other surgical procedures, nor with liposuction or surgical resection of omental fat (8). These observations suggest potential mechanisms beyond weight loss by which RYGB leads to diabetes improvements, but the relative contribution of insulin sensitivity, β-cell function, and other potentially novel mechanisms to improved metabolism following RYGB remain incompletely understood. In this issue, Bojsen-Moller et al. (9) report comprehensive longitudinal assessments of insulin secretion and action at 1 week, 3 months, and 1 year following RYGB in two cohorts of 10 obese patients with and without T2D (Fig. 1). At 1 week, the earliest time point comprehensively assessed to date, fasting glucose has already declined in patients with T2D. Such early improvements are likely mediated by the improvements observed in fasting hepatic …