Cardiovascular autonomic function tests in healthy and diabetic subjects

ABSTRACT

Diabetic autonomic neuropathy [DAN] is common chronic complications of diabetes mellitus [DM] that occur in nearly half of diabetic patients. DAN in patients with diabetes is an irreversible complication, but early detection is important because the condition can't be reversed. The present study was undertaken primarily to investigate cardiovascular autonomic functions in normal healthy individuals and patients with diabetes mellitus [type 1 and type 2 diabetes mellitus; T1DM and T2DM], and to determine the relationship between diabetes and extent of autonomic function impairment. Autonomic functions using five standard tests were examined in 40 diabetic patients and 40 age and sex matched controls. The extent of autonomic dysfunction was determined in the patients. All the patients and the controls were subjected to measurement of heart rate [HR] and P-R interval were monitored from lead II of the ECG and BP was measured by electrosphygmomanometry. Significant [p <0.001] increase in resting heart rate in T2DM [112 +/- 10 bpm] than T1DM [65 +/- 12 bpm] associated with significant decrease in HR variation daring deep breathing T2DM [8 +/- 3 bpm] compared to T1DM [18 +/- 5 bpm], significant decrease in HR response to standing in T2DM [0.7 +/- 0.2 bpm] compared to T1DM [1.06 +/- 0.2 bpm], significant decrease in postural changes in SBP in T2DM [-15 +/- 3 mmHg] compared to T1DM [-3 +/- 8 bpm] and significant decrease in DBP response to hand grip inT2DM [6 +/- l mmHg] compared to T1DM [20 +/- 7 mmHg] within 2-5 years of both types of DM. Moreover, no significant difference between T1DM and T2DM in cardiovascular autonomic function tests after 5 years of DM. Autonomic dysfunction was significantly more frequent in type 2 diabetes mellitus [T1DM] compared with type 1 diabetes mellitus [T2DM]. This study showed that autonomic neuropathy is common in diabetic patients, and that it increases in severity with increase in extent of T2DM, and starts after 5 years in T1DM suggesting that diabetes mellitus contributes to these neurological derangements