We measured simultaneously gastric emptying of digestible and indigestible solids in 10 normal subjects and in 14 insulin-requiring diabetic patients. Our results demonstrate that in both diabetics and in controls the gastric emptying of digestible and indigestible solids occurs during the same phase of gastric motor activity, i.e. during the post-prandial period. However, gastric emptying of both digestible and indigestible solids is delayed in diabetic patients compared to controls.