To describe oesophageal function in people with diabetes and poor glycaemic control using oesophageal high-resolution manometry and to compare the result between control subjects and patients with gastro-oesophageal reflux disease. The results of oesophageal high-resolution manometry and a gastric emptying test were reviewed in 20 patients with diabetes. The high-resolution manometry protocol consisted of 5-ml swallows of water and multiple swallows of water. Oesophageal motility disorders were classified according to the Chicago classification system. The occurence of multiphasic contractions and intragastric and intrabolus pressures were measured. High-resolution manometry results were compared between 10 control subjects and 20 patients with gastro-oesophageal reflux disease. Data were expressed as medians and compared using Mann-Whitney and chi-squared tests. Oesophageal motility disorders were similarly distributed between the groups. Multiphasic contractions occurred more frequently in patients with diabetes than in those with gastro-oesophageal reflux disease (60 vs 20% per patient; P<0.01) and were not observed in control subjects. Gastric emptying was delayed in six patients with diabetes and did not correlate with symptoms or oesophageal motility disorders. Intrabolus pressure was higher in patients with diabetes and gastroparesis than in those without (17 vs 10 mmHg; P=0.02) and correlated with intragastric pressure (r=0.46, P<0.01). During multiple swallows of water, oesophageal contractile activity was incompletely inhibited in 83% of patients with diabetes and gastroparesis vs 9% without (P<0.01). Oesophageal function and gastric emptying were not influenced by fasting glycaemia. Patients with gastroparesis might present with impaired inhibition of contractile activity during multiple swallows of water. Increased intrabolus pressure is suggestive of delayed oesophageal clearance as a consequence of gastroparesis.