Study to Assess Pharmacodynamics of RM-131 in Patients With Diabetic Gastroparesis

Key Inclusion Criteria: * Able to provide written informed consent prior to any study procedures. * Diagnosis of Type 1 or 2 diabetic gastroparesis. * Controlled Type 1 or 2 diabetes mellitus (HbA1c \<10.1%). * Stable concomitant medications defined as no changes in regimen for at least 2 weeks prior to Period 1 (daily adjustments of insulin doses are permitted). * Body mass index of 18-40 kg/m². Key Exclusion Criteria: * Unable or unwilling to provide informed consent or to comply with study procedures. * History of gastric surgery such as fundoplication, gastrectomy, gastric pacemaker placement, vagotomy, bariatric procedure. (Note: history of diagnostic endoscopy is not exclusionary). * Acute or chronic illness or history of illness, which in the opinion of the Investigator, could pose a threat or harm to the patient or obscure interpretation of laboratory test results or interpretation of study data such as frequent angina, Class III or IV congestive heart failure, poor renal or hepatic function, etc. * Any clinically significant abnormalities on screening laboratories as determined by the Investigator. * Abnormal 12-lead electrocardiogram (ECG), including evidence of acute myocardial or subendocardial ischemia and clinically significant arrhythmias or conduction abnormalities or blood pressure at screening except minor deviations deemed to be of no clinical significance by the Investigator. * Poor venous access or inability to tolerate venipuncture. * Acute GI illness within 48 hours of Period 1. * Positive pregnancy test. * Participation in a clinical study within the 30 days prior to dosing in the present study. * Any other reason, which in the opinion of the Investigator, would confound proper interpretation of the study.