Delayed Heart Rate Recovery and Exaggerated Blood Pressure Response during Exercise Testing in Nigerian Normotensive Diabetics

Aim: The aim of this study was to identify the clinical profile of normotensive Type 2 diabetes mellitus (T2DM) with exercise related exaggerated systolic blood pressure (ESBP) and delayed heart rate recovery (HRR); and explore if there is relationship between ESBP and delayed HRR in them.

Materials and Methods: A total of 67 normotensive T2DM subjects underwent symptom limited maximal treadmill exercise using Bruce protocol. ESBP was defined as a peak exercise systolic blood pressure (BP) ≥210 mmHg in men and ≥190 mmHg in women. HRR was defined as the difference in HR from peak exercise to 1 min in recovery; delayed HRR was defined as ≤12 beats/min. Parameters of 36 subjects with ESBP were then compared with those of 31 subjects without ESBP.

Results: There were 36 (53.7%) of the subjects with ESBP. Subjects with ESBP response had higher BMI, 2-hours post-prandial plasma glucose, resting SBP and DBP. Of those with ESBP, 41.7% were males and 58.3% were females (X2=8.75, P=0.003). HRR was lower in subjects with ESBP compared with those without (23.00 ± 12.18 vs 38.55±22.69 beats/minute; P =0.001). The presence of abnormal HRR was 30.6% in subjects with ESBP response compared with 9.7% in subjects without (X2= 4.39, P = 0.036).

Conclusion: ESBP response to exercise is present in more than half of normotensive diabetics and about a third of those patients with ESBP have delayed HRR. Imbalance in the autonomic nervous system, probably heightened sympathetic nervous system, may be responsible for these pathologies.