The present invention provides compositions for use in the treatment of long-established type 1 diabetes (T1D) using peptides and analogs of heat shock protein 60 (Hsp60). The invention is exemplified using DiaPep277, a peptide analog of human Hsp60, which is shown to induce increase in plasma C-peptide and regeneration of islet beta cells. The invention further relates to regimens useful for treatment of long established T1D in patients having no demonstrable islet beta cell-function.