hypoglycaemia and cardiac arrhythmias in type 1 diabetes

Conditions: Hypoglycemia (Diabetic); Hyperglycaemia (Diabetic); Arrythmia, Cardiac; Type 1 Diabetes; Blood Glucose Fluctuations

Summary: the investigators hypothesise that patients with type 1 diabetes have clinically relevant, but often unrecognised, episodes of arrhythmias linked to episodes of hypoglycaemia and/or clinically significant fluctuations in plasma glucose.

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

Eligibility criteria:
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)