Cardiovascular autonomous dysfunction in diabetics: The influence of disease duration, glycoregulation degree and diabetes type

Abstract

INTRODUCTION Cardiovascular autonomous neuropathy (CAN) in diabetes has not been still defined clinically and aetiopathogenetically. OBJECTIVE The aim of this study was to determine the influence of disease duration, glycoregulation degree and diabetes type on damage of the cardiovascular part of the autonomous nervous system in our group of patients. METHOD This study included diabetics, (100 patients) the same number of patients with diabetes type I and II as well as 20 healthy individuals in the control group. Classic Ewing's cardiovascular tests were used for CAN diagnosis: 1. the cardiovascular response to Valsalva manoeuvre, 2. the cardiovascular response to deep breathing (the so-called E/I ratio), 3. the cardiovascular response to rising (the so-called 30/15 ratio), 4. the test of orthostatic hypotension and 5. the TA response to handgrip. It has been arbitrarily taken that patients, whose score of 'parasympathetic' tests (Valsalva manoeuvre, E/I ratio, 30/15) is equal or bigger than 1.5 (out of possible 3), have damage of the parasympathetic part of the autonomous nervous system while patients, whose score of 'sympathetic tests' (the test of orthostatic hypotension and TA response to hand-grip is equal or bigger than 1 (out of possible 2), have damage of the sympathetic part of the autonomous nervous system. The patients whose total score is equal or bigger than 2 have cardiovascular autonomous neuropathy. The glycoregulation degree is determined by the level of HbA1c. RESULTS There is a statistically significant, positive correlation between the values of the parasympathetic score and disease duration as well as between the total score, that is, CAN and disease duration. The connection between the sympathetic score, that is, damage of the sympathetic part of the autonomous nervous system and disease duration has not been observed. There is a positive correlation between the values of the parasympathetic score and HbA1c. The same pattern exists regarding the ratio of damage of the sympathetic part of the autonomous nervous system and the value of HbA1c, as well as the ratio of CAN, that is, the total score and HbA1c. Almost two- fold, a bigger coefficient of correlation between the sympathetic score and HbA1c in relation to the coefficient of correlation of the parasympathetic score and HbA1c, points to bigger sensitivity of the sympathetic part of the autonomous nervous system to subacute deterioration of glycoregulation. The correlation between the values of autonomous scores and diabetes type has not been noted. CONCLUSION Our results show that besides disease duration, the subacute deterioration of glycoregulation also leads to the appearance of cardiovascular autonomous dysfunction in diabetes. The sympathetic nervous tissue is functionally more sensitive than the parasympathetic one to metabolic disorders in diabetes. The cardiovascular autonomous dysfunction will occur independently of the type of diabetes.

Keywords

• CAN
• diabetes mellitus
• HbA1c