The role of the beta cell in type 2 diabetes: new findings from the last 5 years.

Recent advances in genome-wide approaches, the availability of isolated human islets for research and the evaluation of novel incretin mimetics in large clinical trials have brought about remarkable progress in our understanding of the role of the pancreatic beta cell in type 2 diabetes. Here, we review key developments in type 2 diabetes initiation, progression and remission, focusing mostly on human studies published in the last 5 years. Progress in multi-omics technologies has enabled researchers to identify links between type 2 diabetes risk variants and gene regulatory networks in islet endocrine cells that control beta cell development, function and stress resilience. These studies support the notion that early abnormalities in insulin secretion, rather than a reduction in beta cell mass, play a fundamental and primary role in early type 2 diabetes pathogenesis. Contributing to these intrinsic beta cell defects are various pathogenic signals from other (endocrine and non-endocrine) islet cells, the exocrine pancreas, the gut and insulin-sensitive tissues. It has also become apparent that beta cells comprise a heterogeneous population that responds differently to stress situations and that sex-related differences in beta cell responses should not be underestimated. Finally, human clinical trials have clearly demonstrated that diabetes remission can be achieved using glucose-lowering therapies and particularly strategies focused on weight loss, including bariatric surgery and, more recently, the use of highly efficient new drugs targeting the incretin system. While progress in the last 5 years has been significant, much remains to be uncovered to bring these advances to the clinic and thereby alleviate the dramatic consequences of type 2 diabetes complications for the hundreds of millions of people who live with this disease.