Sympathetic Hyperactivity and Its Relationship with Obesity in Diabetic Hypertensive Patients: A Study of 122 Cases

Introduction: The circadian rhythm of heart rate reflects the balance of activity in the autonomic nervous system. The relationship between sympathetic activity and the presence of hypertension (HTN) or diabetes has been a subject of significant study for many years.

Methods and Results: We conducted a descriptive retrospective study including 122 diabetic and hypertensive patients who underwent ambulatory blood pressure monitoring over a period of 4 years. The mean age was 60.9 ± 13.3 years, ranging from 19 to 95 years. Women comprised 62.3% of the sample. Among the patients, 31.97% were obese and 44.26% were overweight. The average heart rate was 69.50 ± 8.6 beats per minute. A similar profile to the reverse dipper blood pressure pattern, defining sympathetic hyperactivity, was observed in our series. In bivariate analysis, obesity was present in 43.75% of patients with sympathetic hyperactivity compared to 41.56% in those with normal circadian rhythm (p >= 0.999). This finding was reinforced in multivariate analysis, which showed a significant correlation between body mass index (BMI) and sympathetic hyperactivity (OR=0.582 [0.232; 1.46], p=0.7297).

Discussion: Insulin resistance is associated with obesity, particularly central obesity. Recent studies have shown the involvement of insulin resistance in the development of hypertension (HTN), which explains the high rate of obese individuals in our series, although this may not be directly related to sympathetic hyperactivity. Currently, the role of sympathetic dysfunction in the genesis or exacerbation of cardiovascular and metabolic disorders is well-established. Research has demonstrated the influence of circadian rhythm on gene and protein expression in cardiac cells, affecting cardiac contraction and electrophysiology. These findings underscore the importance of always exploring the autonomic nervous system in the etiological assessment of metabolic syndrome broadly, and specifically in hypertension and diabetes.