Patients with type 1 diabetes are recommended to perform at least 150 minutes of accumulated physical activity each week, however fear of hypoglycaemia is a well-known barrier to exercise in these patients. Previous experimental studies have almost exclusively focused on investigating cardiovascular effects of hypoglycaemia under resting conditions, however other underlying circumstances prior to or during a hypoglycaemic event, (e.g. exercise) are rarely discussed in the literature but might, nevertheless, be of significant clinical importance.

In this study, the investigators aim to investigate the QT interval dynamics and prothrombotic factors during exercise-related hypoglycaemia in comparison with hypoglycaemia under resting conditions, in patients with type 1 diabetes.

Fifteen patients with type 1 diabetes will be recruited for a crossover study including two test days, a combined euglycaemic- hypoglycaemic clamp combined with an exercise session and an euglycaemic- hypoglycaemic clamp during bed rest, respectively. Furthermore, the participants will be schedueled for a 24-hours followup visit after each test day for the purpose of investigating prolonged prothrombotic effects of hypoglycaemia. Patients will be randomised 1:1 to start with the combined exercise-clamp or the resting-clamp. The two test days will be separated by at least 4 weeks to minimise carry-over effects. A group of fifteen healthy individuals with normal glucose tolerance matched for age, gender and body mass index, will be recruited for a single blood test aiming to compare baseline coagulation status with patients with type 1 diabetes.

Inclusion Criteria:

• Informed and written consent
• Type 1 diabetes diagnosed according to the criteria of the World Health Organization (WHO)
• Age ≥ 18 years
• Insulin treatment for ≥1 year

Exclusion Criteria:

• Arrhythmia diagnosed prior to the screening visit.
• Ischaemic heart disease or myocardial infarction diagnosed prior to the screening visit.
• Implantable cardioverter defibrillator (ICD) or pacemaker at the time of inclusion
• Heart failure (left ventricular ejection fraction <45%) diagnosed prior to the screening visit.
• Structural heart disease (Wolf-Parkinson-White syndrome, congenital heart disease, severe valve disease)
• ECG with left or right bundle branch block diagnosed prior to the screening visit.
• Thyroid dysfunction (except for well-regulated levothyroxine-substituted myxoedema)
• Anaemia (male: haemoglobin <8.0; female: haemoglobin <7.0 mmol/l)
• Treatment with anticoagulant or antiplatelet treatment.
• Bleeding disorder diagnosed prior to the screening visit.

Withdrawal criteria

- The participants may withdraw at will at any time