Insulin is produced and secreted by pancreatic β cells in the pancreas, which plays a key role in maintaining euglycemia. Insufficient secretion or deficient usage of insulin is the main cause of diabetes mellitus (DM). Drug therapy and islets transplantation are classical treatments for DM. Pancreatic β cell replacement therapy could help patients to get rid of drugs and alleviate the problem of lacking in transplantable donors. Pancreatic β-like cells can be acquired by cell reprogramming techniques or directed induction of stem cell differentiation. These cells are proved to be functional both in vitro and in vivo. Some hospitals have already performed clinical trials for pancreatic β cell replacement therapy. Functional pancreatic β-like cells, which obtained from in vitro pathway, could be a reliable source of cell therapy for treating DM. In this review, the approaches of obtaining pancreatic β cells are summarized and the remaining problems are discussed. Some thoughts are provided for further acquisition and application of pancreatic β cells.