Clinical complications in high glucose levels must be seen in the context of a nearly complete blockade of sympathetic and parasympathetic activity. Basically to extreme autonomic restriction, sympathetic and vagal predominance can change rapidly into each other. This retarded vulnerable predisposition may declare the arrhythmic potential. An important progress in the monitoring of patients could be achieved by implementation of a continuous HRV measurement because hereby the actual risk potential can be ascertained timely and reliably.