Gastric emptying of technetium labeled liquid and solid meals were studied in a group of long-standing, insulin-requiring male diabetics to evaluate the relationship of gastroparesis to symptoms, diabetic control, and diabetic complications. Control subjects and three groups of diabetics were studied: A) no neuropathy; B) peripheral neuropathy; and C) peripheral and autonomic neuropathy. Nine diabetics had gastrointestinal symptoms. Gastric t1/2 liquid emptying was similar in all groups and in controls, but liquid gastric emptying in the first 15 min was significantly more rapid in the diabetics than controls. Solid emptying was prolonged in group C patients. There was a significant correlation between t1/2 solid emptying and the severity of neuropathy. The eight patients with slow solid emptying had more neuropathy and gastrointestinal symptoms than the remaining 22 patients. The type and duration of diabetes, diabetic control, and frequency of retinopathy are independent of gastroparesis. These data indicate that delayed emptying of solids is common (27%) in patients with clinically detectable neuropathy and may often be asymptomatic. Visceral autonomic neuropathy seems the most important underlying factor in diabetic gastroparesis.