The aim of this Phase I/IIa study is to identify a safe and tolerable dosage regimen of intravenously administered otelixizumab. In addition, the C-peptide decline in new onset type 1 diabetes mellitus (NOT1DM) patients and possible immunological mechanisms will be investigated with a view to identifying trends and early immunological biomarkers which could predict response in halting/slowing Beta-cell destruction in this patient population.