Goto–Kakizaki (GK) rat is an experimental model of spontaneous and non‐obese type‐2 diabetes mellitus—T2DM).GK rats exhibit decreased small intestinal area, increased crypt depth, villi height and thickness, and muscular layer thickness, increased content of IL‐1β and NF‐κB p65, decreased density of submucosal neurons, myenteric and submucosal neuronal and ganglionic hypertrophy, and decreased intestinal transit.The development of IR and T2DM in GK rats is associated with small intestine remodeling with marked changes in morphology, enteric nervous system, and transit. Here, NFKB1 is linked to type 2 diabetes mellitus.