Cardiovascular Reflex Tests in Adolescents with Type 1 Diabetes Mellitus

Background: Diabetic autonomic neuropathy (DAN) is one of the serious, microvascular complications of diabetes mellitus. Clinically the most important form of DAN is cardiovascular autonomic neuropathy (CAN). Determination of the presence of CAN is usually done by a battery of cardiovascular reflex tests. This study was aimed to compare the standard cardiovascular reflex tests between adolescents with diagnosed type 1 diabetes mellitus (T1 DM) and Healthy Controls.
Methods: A total of 64 subjects were recruited for this study. Mean age of case group was 16.15 ± 2.66 years and the mean age of control group was 17.13 ± 1.34 years. Mean duration of diabetes in them was 54.81± 33.57 months. Standard cardiovascular tests such as deep breathing test (DBT), Valsalva ratio (VR), Lying to standing test (LST or 30: 15 ratio) and cold pressor test (CPT) were performed.
Results: We found a significantly reduced LST (30: 15 ratio) in diabetic group. We also found a significantly reduced change in diastolic blood pressure (∆DBP) at 1 minute of CPT in diabetic group. Furthermore, greater the duration of disease lesser was the DBT.
Conclusions: A significantly reduced LST (30: 15 ratio) in diabetic group signifies reduced parasympathetic activity. Significantly a reduced value of ∆ DBP at the end of 1 minute of CPT implies a reduced sympathetic activity in this group of patients. It can be said that in these patients autonomic activity is compromised. Furthermore, the impairment in parasympathetic activity (DBT) is directly related to the duration of diabetes