Glargine is a long lasting bioengineered insulin analogue commonly used in the medical treatment of insulindependent diabetes mellitus. After subcutaneous injection, glargine undergoes enzymatic process generating two metabolites, M1 and M2. Quantitative evidences of their presence and concentration after doping multiple concentrations are important for clinical study. Such information can also help to understand the pharmacokinetics, pharmacodynamics, and toxicology during the insulin drug development. We developed and validated a high throughput analytical method coupled with solid-phase extraction (SPE) and LC-MS/MS for the quantitation of intact insulin in plasma samples for use in pre-clinical and clinical studies. The multiple-reaction-monitoring (MRM) experiments performed on a triple-quadruple mass spectrometry instrument were used for quantitation. A 3.5 min UHPLC method was developed to achieve high throughput. An eight-point standard calibration curve with concentration from 0.2 ng/mL to 20 ng/mL was constructed corresponding to the normal non-fasting insulin levels in plasma. The acceptance criteria for values of accuracy, precision, and linearity of the quantitation curve were developed in accordance to the bioanalytical method validation guidance published by Food and Drug Administration (FDA) and European Medicines Agency (EMA). This validated MRM method was applied for toxicity study of insulin analogues in dog. The toxicokinetic results were reported. Moreover, we compared the MRM results to the MS quantitation results acquired on a hybrid quadruple-quadruple time-of-flight (QqTOF) and showed the high resolution instrument can be an option for peptide and biotherapeutic protein quantitation.