We evaluated whether chronic nausea and vomiting in diabetic patients correlate with abnormal gastric emptying of liquid or solid, or both liquid and solid, radiolabeled meals and recorded the acute effects of metoclopramide. last, we compared several methods of analyzing gastric emptying data obtained using the gamma-camera. Eighteen healthy control subjects and 16 insulin-dependent diabetics with neuropathy were investigated. Ten of the patients suffered from chronic nausea and vomiting; the remaining 6 served as disease controls. Gastric emptying of solid and liquid meals could best be described by the slopes of two linear components and their intercept. Liquid meals generally were handled normally, while solid meals were emptied slowly by both groups of diabetics. A single dose of metoclopramide frequently corrected the delayed onset of the second, more rapidly emptying phase, that is, the major abnormality of solid emptying. The radiologic findings during a barium meal did not distinguish symptomatic from asymptomatic patients. We conclude that abnormal gastric motor function, manifested by delayed emptying of a solid meal or barium suspension, or both, is common in diabetics with neuropathy and that this motor abnormality is not the only cause of chronic vomiting. The beneficial, often short-term symptomatic effects of metoclopramide in these patients appear to be mediated by a combination of normalization of gastric emptying and a central antiemetic action.