• Prevalence of cardiac arrhythmias [ Time Frame: Within 12 months ]
  Prevalence of clinically relevant arrhythmias
• Cardiac arrhythmias during LGV, HGV. [ Time Frame: Within 12 months ]
  Clinical relevant arrhythmias during low glucose variability (LGV), defined as variations in plasma glucose below or equal to 5 mmol/l within two hours preceding an arrhythmic event, compared to high glucose variability (HGV), defined as variations in plasma glucose above 5 mmol/l within two hours preceding an arrhythmic event.
• The relationship between cardiovascular disease at baseline and clinically relevant arrhythmias in relation to hypoglycaemia and HGV [ Time Frame: Within 12 months ]
  The relationship between cardiovascular disease (heart failure and ischaemic heart disease) at baseline and clinically relevant arrhythmias in relation to hypoglycaemia and HGV
• The relationship between pharmacological treatment at baseline and clinically relevant arrhythmias in relation to hypoglycaemia and HGV [ Time Frame: Within 12 months ]
  The relationship between pharmacological treatment at baseline and clinically relevant arrhythmias in relation to hypoglycaemia and HGV
• The relationship between diabetes complication status at baseline and clinically relevant arrhythmias in relation to hypoglycaemia and HGV [ Time Frame: Within 12 months ]
  The relationship between diabetes complication status (neuropathy, nephropathy, retinopathy) at baseline and clinically relevant arrhythmias in relation to hypoglycaemia and HGV
• Hypoglycaemia and cardiac arrhythmia [ Time Frame: Within 12 months ]
  The correlation between prevalence and total duration of hypoglycaemia and risk of clinically relevant arrhythmias
• Plasma glucose variation and cardiac arrhythmias [ Time Frame: Within 12 months ]
  The correlation between plasma glucose variation (variation in plasma glucose (Δ mmol/l) within two hours of the event) and risk of clinically relevant arrhythmias
• CV, SD, ADRR, LBGI, HBGI, CONGA-1 and cardiac arrhythmias [ Time Frame: Within 12 months ]
  The correlation between measures of glycaemic variability (coefficient of variation (CV), standard deviation (SD), average daily risk range (ADRR), low blood glucose index (LBGI), high blood glucose index (HBGI) and continuous overlapping net glycaemic action (CONGA-1)) and risk of clinically relevant arrhythmias
• Mean amplitude of glycaemic excursions (MAGE) and cardiac arrhythmia. [ Time Frame: Within 12 months ]
  Difference in mean amplitude of glycaemic excursions (MAGE) two hours preceding an arrhythmic event versus MAGE during non-event

30 patients with type 1 diabetes will be recruited for a one-year observational study employing CGM (Continuous glucose monitor) and ILR (Implantable loop recorder). Patients will be scheduled for a three-week run-in period to ensure that the implanted ILR provides reliable data. Patient visits are planned for 0, 3, 6, 9, and 12 months and will include clinical examination, blood and urine samples, echocardiography (only first and last visit) and implant/explant of CGM. After 12 months, the participants will continue with an extended observation period of 2 years employing ILR and clinical examination.

Device: Loop recorder (Reveal LINQ, Medtronic, Minneapolis, MN, USA) Implantation of a loop-recorder

Device: Continuous glucose monitoring (Eversense XL, Senseonics, USA) Monitoring with a continuous glucose monitor

• Hypoglycemia (Diabetic)
• Hyperglycaemia (Diabetic)
• Arrythmia, Cardiac
• Type 1 Diabetes
• Blood Glucose Fluctuations

Inclusion Criteria:

• Informed and written consent
• Type 1 diabetes diagnosed according to the criteria of the World Health Organization (WHO)
• Age 18-80 years

• Fulfilling at least one of the below criteria*:

  1. Recurrent hypoglycaemia (defined as >1 episode/week with a plasma glucose measurement ≤3.9 mmol/l within the last 4 weeks)
  2. An episode of severe hypoglycaemia within the last year (according to the ADA definition, an event requiring assistance of another person to actively administer carbohydrates and/or glucagon, or take other corrective actions)
  3. Hypoglycaemic symptom unawareness (history of impaired autonomic response during hypoglycaemia)

(*The aim is that all patients will fulfil criteria a or b. If the targeted sample size cannot be recruited, patients fulfilling criteria c will be included)

• Insulin treatment

• One or more clinical relevant complications to diabetes defined as**:

  1. Nephropathy (creatinine >130 μmol/l and/or microalbuminuria)
  2. Macrovascular disease defined as coronary disease (stable angina pectoris. previous unstable angina pectoris or myocardial infarction), cerebrovascular disease (previous stroke or transitional cerebral ischaemia), and peripheral vascular disease (previous intermittent claudication or prior acute ischemia)
  3. Peripheral neuropathy with vibration perception threshold of >25 volt determined by biothesiometry
  4. Moderate to severe retinopathy
• Well-functioning ILR during run-in period (acceptable readings judged by an arrhythmologist)
• Participation in the extended study

(**The aim is that all patients will fulfil criteria a or b. If the targeted sample size cannot be recruited, patients fulfilling criteria c or d will be included)

Exclusion Criteria:

• Arrhythmia diagnosed prior to the screening visit
• ICD or pacemaker at the time of inclusion
• Severe heart failure (left ventricular ejection fraction <25%)
• Structural heart disease (Wolf-Parkinson-White syndrome, congenital heart disease, severe valve disease)
• Thyroid dysfunction (except for well-regulated eltroxine substituted myxoedema)

• University of Copenhagen
• University Hospital, Gentofte, Copenhagen
• Hillerod Hospital, Denmark