It has previously been shown that insulin is secreted in discrete secretory bursts by sampling directly from the portal vein in the dog and humans. Deficient pulsatile insulin secretion is the basis for impaired insulin secretion in type 2 diabetes. However, while novel genetically modified disease models of diabetes are being developed in rodents, no validated method for quantifying pulsatile insulin secretion has been established for rodents. To address this we 1) developed a novel rat model with chronically implanted portal vein catheters, 2) established the parameters to permit deconvolution of portal vein insulin concentrations profiles to measure insulin secretion and resolve its pulsatile components, 3) measured total and pulsatile insulin secretion in comparison to that in the dog, the species in which this sampling and deconvolution approach was validated for quantifying pulsatile insulin secretion. In rats, portal vein catheter patency and function was maintained for periods up to 2-3 weeks with no post-operative complications such as catheter tract infection. Rat portal vein insulin concentration profiles in the fasting state revealed distinct insulin oscillations with a periodicity of ~5 minutes and an amplitude of up to 600 pmol/l which was remarkably similar to that in the dogs and in humans. Deconvolution analysis of portal vein insulin concentrations reveled that the majority of insulin (~70%) in the rat is secreted in distinct insulin pulses occurring at ~5 minute intervals. This model therefore permits direct accurate measurments of pulsatile insulin secretion in a relatively inexpensive animal and with increased introduction of genetically modified rat models, will be an important tool in elucidating underlying mechanisms of impaired pulsatile insulin secretion in diabetes.