The present invention is directed to novel substituted dihydropyrrolopyrazoles of structural Formula I which are inhibitors of the dipeptidyl peptidase-N enzyme and which are useful in the treatment or prevention of diseases in which the dipeptidyl peptidase-IV enzyme is involved, such as diabetes and particularly Type 2 diabetes. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which the dipeptidyl peptidase IV enzyme is involved.Cette invention concerne de nouveaux dihydropyrrolopyrazoles substitués de formule structurale I qui représentent des inhibiteurs de lenzyme dipeptidyl peptidase-N et qui sont utilisés pour traiter ou prévenir des maladies dans lesquelles lenzyme dipeptidyl peptidase-IV est impliquée, telles que le diabète et en particulier le diabète de type 2. Cette invention concerne en outre des compositions pharmaceutiques comprenant lesdits composés ainsi que lutilisation de ces composés et compositions pour prévenir ou traiter ces maladies dans lesquelles lenzyme dipeptidyl peptidase IV est impliquée.