[Blood pressure and heart rate regulation in diabetics]

Cardiac autonomic neuropathy (CAN) is frequent in subclinical stages. Its prognostic value has been demonstrated. Cardiac autonomic neuropathy induces different functional cardiac changes, especially a reduction in left ventricular contractility and changes in ventricular repolarisation. It is also associated with changes in the daily variations in blood pressure. The association of CAN and silent myocardial ischaemia significantly worsens the prognosis. The investigation of CAN in the greatest number of diabetic patients is therefore justified. The study of heart rate variations during deep respiration, active orthostatism or Valsalva manoeuvre, is still the reference. This method is simple, reproducible and may be carried out in the clinical setting in 10 to 15 minutes. The results must be strictly interpreted with rigour with respect to age. Orthostatic hypotension is a late sign of sympathetic nervous system disease. Spectral analysis of blood pressure variations on orthostatism or the study of cutaneous blood flow during activating the sympathetic system tests of greater sensitivity, should be developed. The demonstration of subclinical CAN should lead to the careful use of drugs which may induce orthostatic hypotension and certain antiarrhythmics, to search for disorders of ventricular repolarisation and for silent myocardial ischaemia in diabetics with several risk factors.