IMPORTANCE OF THE FIELD: Type 1 diabetes mellitus (T1D) is a T-cell mediated 
autoimmune disease with selective destruction of beta cells. Immunological 
interventions are directed at arresting the loss of beta-cell function with the 
promise that this will make it easier for patients to control their glucose 
levels.
AREAS COVERED IN THIS REVIEW: This review provides a summary of the preclinical 
and clinical research published between 1992 and 2009 using teplizumab and other 
anti-CD3 antibodies to arrest the loss of beta-cell function in new onset T1D. 
Data from animal and human studies on the probable mechanism of action of 
teplizumab are also reviewed.
WHAT THE READER WILL GAIN: A broad perspective on the use of teplizumab in 
inducing disease specific tolerance.
TAKE HOME MESSAGE: In Phase I/II randomized control trials, in patients with new 
onset T1D, teplizumab slowed the rate of loss of beta-cell function over 2 years 
of follow-up. Treated patients had better glycemic control and lower insulin 
requirements. Adverse events so far are mild and of limited duration. Phase III 
clinical trials are underway to confirm these results and to determine if two 
courses of drug have greater efficacy in arresting loss of beta-cell function.