In this study, food distribution in the stomach and gastric antral motor activity in patients with longstanding diabetes have been evaluated. With use of a standard gastric emptying test with an acquisition protocol and a refined Fourier algorithm to analyze the data, antral contractions have been characterized and gastric motility parameters were correlated to gastric retention in 20 diabetic patients with or without gastroparesis and in 10 healthy subjects. The results of this study show that, in longstanding diabetes, gastric emptying retardation is accounted for by a retention of food in the proximal stomach, which is reflected by a prolonged lag phase as well as by a reduction in antral motor activity that is determined by a decrease in the amplitude of the antral contractions. This study demonstrates that scintigraphy can noninvasively characterize abnormalities of food distribution in the stomach and provides information similar to that obtained from manometry.