We measured gastric emptying and gastric myoelectrical activity with solid-phase gastric-emptying tests and cutaneously recorded electrogastrograms (EGGs), respectively, in six insulin-dependent diabetic patients with nausea and vomiting who did not respond to standard treatments. Baseline solid phase gastric emptying was markedly delayed (78 +/- 8% retained at 120 min) and EGG recordings revealed gastric dysrhythmias; tachygastria (4-9 cpm signals) in one patient, 1- to 2-cpm waves in two patients, and flatline patterns in three patients. No patient had a normal 3-cpm EGG pattern. After 6 months of domperidone treatment, mean upper gastrointestinal symptoms scores decreased from 17.8 to 3.7 (p less than 0.01), and normal 3-cpm EGG frequencies were recorded from each of the six patients. The mean percentage of meal retained at 120 min decreased but did not improve significantly. Thus, establishment of normal 3-cpm gastric myoelectric activity and resolution of dysrhythmias, not normalization of emptying rates, was associated with improvement in upper gastrointestinal symptoms in these diabetic patients.