Hypoglycaemia-induced cardiac arrhythmia as the background of recurring syncope in an old patient with diabetes and cardiovascular autonomic neuropathy - a case report

Hypoglycaemia increases the risk of falls, unconsciousness, seizures and dementia in the elderly population. Besides, deepening hypoglycaemia precipitates QT -prolongation, premature cardiac beats and conduction abnormalities. The old diabetic patient (female, age: 84 ys; HbA1c 7.0%; BMI: 26.8 kg/m2) was admitted to hospital due to recurring episodes of collapse. During the last event of losing consciousness, severe hypoglycaemia was detected (glucose: 1.7 mmol/l). On clinical admission, the electrocardiogram (ECG) recording showed QT -interval prolongation and Mobitz type II 2nd degree AV block being in accordance with findings of a Holter test performed in the preceding weeks. The decade -long used sulfonylurea (SU) was omitted and the DPP4-inhibitor sitagliptin was added on to metformin as glucose -lowering medication. Neither cardiac conduction abnormalities nor arrhythmias returned during the patient's hypoglycaemia -free hospital observation and Holter monitoring. Long-lasting severe hypoglycaemia as a side -effect of SU treatment could account for the cardiac arrhythmia. As for differential diagnosis, carotid ultrasound revealed significant stenosis of the left carotid artery (80-85%) and echocardiographic imaging was negative. Diabetic sensorimotor polyneuropathy and mild -to -moderate cardiovascular autonomic neuropathy was established. However, the role of orthostatic hypotension could be excluded.