GCG and type 2 diabetes mellitus: One example is the prediction of postprandial glucose and insulin plasma levels under the effect of glucagon-like peptide-1 (GLP-1) and incretins activating glucagon-like peptide-1 receptors (GLP-1R) for normal and type 2 diabetic subjects by integrating four heterogeneous models: a structural model of GLP-1R activation, a signaling network model of insulin secretion pathway in pancreatic β-cells, a linear model of a pancreatic cell population and a mathematical ODE model of system postprandial response.