GCG and type 2 diabetes mellitus: Additionally, pancreatic neuronal activity is also impaired in T2D.163 The pancreas is richly innervated by the sympathetic and parasympathetic nervous system.164 The cephalic phase of insulin secretion is lost in T2D and glucagon secretion is not suppressed during the fed state.163 This implies that if the nervous system does suppress glucagon secretion in an insulin-independent manner during the fed state in healthy individuals then this is absent in T2D.