INS and diabetes mellitus: Among the studies conducted in mice, the fasting and post-prandial plasma glucose level, the C-peptide level, the rate of change in body weight, the serum insulin level, the total number of islets and the ratio of β and α cells per islet were the outcomes used by most animal studies selected in this systematic review to assess the potential of hMSCs administration for the treatment of type 1 diabetes mellitus.