<b><i>Introduction:</i></b> Dysphagia is a common symptom that occurs in patients with diabetes mellitus (DM). There have been few prospective observational studies on esophageal motility disorders in DM using high-resolution manometry (HRM). This study aimed to clarify the characteristics of esophageal motility disorders using HRM in patients with dysphagia and compare them between DM and non-DM patients. <b><i>Methods:</i></b> Patients with dysphagia were prospectively recruited between October 2018 and July 2019. Patients (<i>n</i> = 89) underwent esophagogastroduodenoscopy and HRM and completed the Gastrointestinal Symptom Rating Scale (GSRS) questionnaire. Manometry parameters and motility disorder classifications were compared between DM and non-DM patients. We also investigated the differences in clinical backgrounds and questionnaire scores among DM patients with normal and abnormal manometry results. <b><i>Results:</i></b> A higher prevalence of esophageal motility disorder was observed in DM patients (60%, 21/35) compared to non-DM patients (29.6%, 16/54) (<i>p</i> = 0.001). The prevalence of minor disorders such as ineffective esophageal motor disorder and fragmented peristalsis was significantly higher (45 vs. 11%), and the distal contractile integral, integrated relaxation pressure, and contractile front velocity values were lower in the DM group. Among DM patients, those with abnormal esophageal motility had a significantly higher prevalence of neuropathy, retinopathy, and nephropathy, as well as higher reflux or constipation scores on the GSRS, than those with normal results. <b><i>Conclusions:</i></b> Among patients with dysphagia, the frequency of minor esophageal motility disorders was higher in DM patients than in non-DM patients. Abnormal esophageal motility related to poor esophageal clearance was associated with higher prevalence of diabetic complications.