Type 1 diabetes mellitus is an autoimmune disease against pancreatic β cells. The autoimmune response begins months or years before the clinical presentation. At the time of hyperglycemic symptoms a small amount of β cell mass still remains. The main therapeutic option to type 1 diabetes mellitus is daily insulin injections which is shown to promote tighter glucose control and to reduce much of diabetic chronic complications. Subgroup analysis of the Diabetes Control and Complication Trial (DCCT) showed another important aspect related to long term complications of diabetes, ie, patients with initially larger residual β cell mass suffered less microvascular complications and less hypoglycemic events than those patients with small amounts of β cells at diagnosis. In face of this, β cell preservation has become another important target in the management of type 1 diabetes and its related complications. In this review, we summarize various immunomodulatory regimens ever used in humans, including stem cell-based strategies, aiming at blocking autoimmunity against pancreatic β cells and at promoting β cell preservation and/or possible β cell regeneration in recent-onset type 1 diabetes.