Deletion of the MC4R in the dorsal motor nucleus of the vagus nerve (DMV), part of the dorsal vagal complex (DVC (Fig. 2))—consisting of preganglionic, parasympathetic nerve cells controlling vagal outflow—results in hyperinsulinemia and modest insulin resistance in a weight-independent manner and without changes in glucose tolerance or blood glucose levels9. Here, MC4R is linked to hyperinsulinism.