Postprandial Blood Glucose Control With BioChaperone® Combo and Insulin Lispro (Humalog®) Mix 25 in People With Type 1 Diabetes Mellitus

Inclusion Criteria: * Type 1 diabetes mellitus (as diagnosed clinically) \>= 12 months. * Treated with multiple daily insulin injections or CSII \>= 12 months. * Current total daily insulin treatment \< 1.2 (I)U/kg/day. * Current total daily bolus insulin treatment \< 0.7 (I)U/kg/day. * Usual Insulin bolus dose between 0.8 and 2 (I)U per 10 g CH (both inclusive). Expecting prandial insulin dose range for standardised meal test between 5 and 12 (I)U. * BMI 18.5-28.0 kg/m\^2 (both inclusive). * HbA1c \<= 9.0% by local laboratory analysis * Fasting C-peptide \<= 0.3 nmol/L. Exclusion Criteria: * Known or suspected hypersensitivity to trial products or related products. * Type 2 diabetes mellitus. * Previous participation in this trial. Participation is defined as randomised. * Participation in any Clinical Trial within 3 months prior to this trial. * Clinically significant abnormal haematology, biochemistry, lipids, or urinalysis screening tests, as judged by the Investigator considering the underlying disease. * Presence of clinically significant acute gastrointestinal symptoms (e.g. nausea, vomiting, heartburn or diarrhoea), as judged by the Investigator. * Known slowing of gastric emptying and or gastrointestinal surgery that in the opinion of the investigator might change gastrointestinal motility and food absorption. * Unusual meal habits and special diet requirements or unwillingness to eat the food provided in the trial. * Women of child bearing potential, not willing to use contraceptive methods.