For obese people with diabetes, doctors have increasingly been offering gastric bypass surgery as a way to lose weight and control blood glucose levels. Short-term results are often impressive, but questions have remained about the long-term benefits of such operations. Now, a large, international study has some answers.
Soon after gastric bypass surgery, about 50 percent of folks not only lost weight but they also showed well-controlled blood glucose, cholesterol, and blood pressure. The good news is that five years later about half of those who originally showed those broad benefits of surgery maintained that healthy profile. The not-so-good news is that the other half, while they generally continued to sustain weight loss and better glucose control, began to show signs of increasing risk for cardiovascular complications.
Caption: Insulin-containing pancreatic beta cells (green) derived from human stem cells. The red cells are producing another metabolic hormone, glucagon, that regulates blood glucose levels. Blue indicates cell nuclei. Credit: The Salk Institute for Biological Studies, La Jolla, CA
In people with type 1 diabetes, the immune system kills off insulin-producing beta cells of the pancreas needed to control the amount of glucose in their bloodstream. As a result, they must monitor their blood glucose often and take replacement doses of insulin to keep it under control. Transplantation of donated pancreatic islets—tissue that contains beta cells—holds some promise as a therapy or even a cure for type 1 diabetes. However, such donor islets are in notoriously short supply . Recent advances in stem cell research have raised hopes of one day generating an essentially unlimited supply of replacement beta cells perfectly matched to the patient to avoid transplant rejection.
A couple of years ago, researchers took a major step toward this goal by coaxing induced pluripotent stem cells (iPSCs), which are made from mature human cells, to differentiate into cells that closely resembled beta cells. But a few things were troublesome. The process was long and difficult, and the iPSC-derived cells were not quite as good at sensing glucose and secreting insulin as cells in a healthy person. They also looked and, in some ways, acted like beta cells, but were unable to mature fully in the lab. Now, an NIH-funded team has succeeded in finding an additional switch that enables iPSC-derived beta cells to mature and produce insulin in a dish—a significant step toward moving this work closer to the clinical applications that many diabetics have wanted.