In previous studies, we tested the feasibility of a bi-hormonal closed loop system. This system for automated control of blood glucose in patients with type 1 diabetes was tested in the clinical research center as well as at the home of the patients. Glucose control with automated closed loop control was comparable to patient-managed open loop control.

The closed loop system has been further developed and miniaturized (from backpack to smartphone size) in order to interfere as little as possible with daily patient life. The aim of this trial is to assess the efficacy of the new prototype at the home of the patient. It is hypothesized that the closed loop system provides better glucose control than standard open loop therapy.

Inclusion Criteria:

• Diagnosed with diabetes mellitus type 1
• Treated with insulin pump therapy for a minimum of 6 months
• Age between 18 and 75 years
• Willing and able to sign informed consent

Exclusion Criteria:

• Impaired awareness of hypoglycemia (score ≥ 4) according to Gold and/or Clarke questionnaire
• BMI > 35 kg/m2
• HbA1c > 97 mmol/mol (=11.0 %)
• Use of heparin, coumarin derivatives or oral corticosteroids
• Skin condition prohibiting needle insertion
• Pregnancy and/or breastfeeding
• Living alone during the closed loop period (the patient may ask someone to stay over temporarily)
• Any condition that the local investigator feels would have interfere with trial participation or the evaluation of the results