Taspoglutide has elicited a long-lasting glycemic control effect with favorable body weight loss. The objective of this study was to develop a quantitative model to delineate the net efficacy of taspoglutide on body weight (WT) loss from the response of placebo in type 2 diabetes patients, and further find pharmacodynamic potency of taspoglutide for half of maximum reduction response of WT. Several PD data about taspoglutide treatments for type 2 diabetes patients were digitalized from the published papers. The model based metaanalysis (MBMA) study for WT loss was performed with Monolix 4.3 software. The MBMA successfully described the effects of placebo and taspoglutide on the pharmacological index of WT loss in clinical trials. The pharmacodynamic potency (41.7 pmol/l) produced 50% of maximum response of WT (-1.85 kg) from the responses of placebo (-1.33 kg). The longitudinal MBMA could be utilized to quantitatively describe the efficacy of taspoglutide on body weight loss and may lead to a clinical guideline for treatment of type 2 diabetes patients in the future.