A Trial to Assess the Efficacy and Safety of M1 Pram P037 Prandial Insulin in Subjects With Type 1 Diabetes (T1DM)

Inclusion Criteria: * Signed and dated informed consent obtained before any trial-related activities. Trial-related activities are any procedures that would not have been done during normal management of the subject. * Subjects with type 1 diabetes mellitus. * Body Mass Index (BMI) between 25.0 and 35.0 kg/m\^2, both inclusive. * HbA1c between 7.0 % and 9.5 %, both inclusive. * Diabetes duration of at least 12 months. * Using a multiple dosing insulin therapy (MDI) with a basal insulin and a rapid-acting insulin at at least two meals per day. * Using any CGM or Flash Glucose Monitoring (FGM) for at least 1 month or willing to use CGM during the trial. Exclusion Criteria: * Known or suspected hypersensitivity to IMPs or any of the excipients or to any component of the IMP formulation. * Type 2 diabetes mellitus. * Receipt of any medicinal product in clinical development within 3 months or at least 5 half-lives of the related substances and their metabolites (whichever is longer) before randomisation in this trial. * History of multiple and/or severe allergies to drugs or foods or a history of severe anaphylactic reaction. * Any history or presence of cancer except basal cell skin cancer or squamous cell skin cancer as judged by the Investigator. * Clinically significant abnormal screening laboratory tests, as judged by the Investigator. * Systolic blood pressure \< 90 mmHg or \>139 mmHg and/or diastolic blood pressure \< 50 mmHg or \> 89 mmHg. One repeat test (on a different day, if necessary) will be acceptable in case of suspected white-coat hypertension. * Clinically significant abnormal standard 12-lead electrocardiogram (ECG) after 5 minutes resting in supine position at screening, as judged by the Investigator. * Proliferative retinopathy or maculopathy as judged by the Investigator based on a recent (\<1.5 years) ophthalmologic examination. * Severe neuropathy, in particular autonomic neuropathy, as judged by the Investigator. * More than one episode of severe hypoglycaemia with seizure, coma or requiring assistance of another person during the past 6 months. * Hypoglycaemic unawareness as judged by the Investigator. * Hospitalisation for diabetic ketoacidosis during the previous 6 months. * Presence of clinically significant gastrointestinal symptoms (e.g., nausea, vomiting, heartburn or diarrhea), as judged by the Investigator. * Confirmed diagnosis of gastroparesis or requiring the use of drugs that alter gastrointestinal motility. * Unusual meal habits and special diet requirements that could constitute a risk for the subject when participating in the trial or interfere with the interpretation of data. * Use of oral antidiabetic drugs (OADs) and/or GLP-1 receptor agonists within 4 weeks prior to screening. * Use of systemic glucocorticoid therapy (excluding topical, intraocular, intranasal, intra-articular, or inhaled preparations) within 2 months prior to screening. * Use or planned use of drugs that promote weight loss (e.g. liraglutide, semaglutide, orlistat, lorcaserin, phentermine) within 2 months prior to screening. * If female, pregnancy or breast-feeding. * Women of childbearing potential who are not using a highly effective contraceptive method. * The Investigator considers a subject as unsuitable for inclusion in the study for any other reason.