["The Journal of Physiology, EarlyView. ", "\nAbstract figure legend ICC calcium (Ca2+) waves typically propagated along the greater curvature from the fundus–corpus line toward the antrum. In diabetic mice with delayed gastric emptying (Db‐DGE), the propagation length of ICC Ca2+ activity was significantly decreased compared to non‐diabetic (Non‐Db) and diabetic with normal gastric emptying (Db‐NGE) mice. The decrease in ICC length of propagation correlated to longer gastric emptying times. There was also a decrease in frequency, and the velocity was significantly faster in stomachs of Db‐DGE mice compared to Non‐Db and Db‐NGE mice. Interestingly, ectopic initiation only occurred in Db‐DGE stomachs.\n\n\n\n\n\n\n\n\n\nAbstract\nInterstitial cells of Cajal (ICC) regulate gastrointestinal motility by generating electrical slow waves that orchestrate downstream calcium (Ca2+) waves and coordinate smooth muscle contractions. A reduced ICC number has been reported in diabetic gastroparesis patients and in mouse models of delayed gastric emptying (DGE). However, functional changes in ICC propagating across the gastric regions in intact stomach are not well understood. The aim of this study was to develop an imaging approach to visualize ICC Ca2+ waves in mouse stomach and determine spatiotemporal changes in mice with DGE. Tamoxifen‐treated B6.GCaMP5‐KitCreERT2 female mice were used as non‐diabetic controls (Non‐Db), while mice treated with streptozocin to induce diabetes were categorized as having normal (Db‐NGE) or delayed (Db‐DGE) gastric emptying based on emptying of solids. The ICC Ca2+ network was imaged from excised intact mouse stomachs and subsequently opened along the lesser curvature and pinned flat. ICC Ca2+ waves typically propagated along the greater curvature from the fundus–corpus line toward the antrum. The propagation length of ICC Ca2+ activity was significantly decreased in Db‐DGE compared to Non‐Db and Db‐NGE and correlated to longer GE times. There was also a decrease in frequency, and the velocity was significantly faster in stomachs from Db‐DGE compared to Non‐Db and Db‐NGE. All experimental groups exhibited similar proportions of aberrant Ca2+ propagation patterns (e.g., retrograde waves), but ectopic initiation only occurred in Db‐DGE stomachs. Thus, DGE is possibly driven by dysfunction in Ca2+ activity in the ICC network that propagates rapidly over short distances, resulting in uncoordinated, non‐phasic muscle activity.\n\n\n\n\n\n\n\n\n\nKey points\n\nDysfunction of the interstitial cells of Cajal (ICC) has been implicated in diabetic gastroparesis but the changes in spatiotemporal properties of ICC network activity are not known.\nWe developed an ex vivo Ca2+ imaging approach to visualize ICC network activity across the entire stomach and determined changes in ICC Ca2+ activity in a diabetic mouse model of delayed gastric emptying (GE).\nDecreased frequency and increased velocity of ICC Ca2+ activity was observed in stomachs of diabetic mice with delayed GE.\nEctopic initiation was a key feature associated with delayed GE.\nThe propagation length of ICC Ca2+ activity was inversely correlated to GE times and significantly reduced in stomach preparations from diabetic mice with delayed GE.\n\n\n"]