Autonomic dysfunction is related to impaired pancreatic β cell function in patients with coronary artery disease

Abstract

Objective - To assess the role of β cell failure in the development of autonomic dysfunction in patients with coronary artery disease. Design - Autonomic function was measured by standard clinical methods and by heart rate variability in 24 type II diabetic and 24 non-diabetic subjects with coronary artery disease. Quantitative estimates of pancreatic β cell function (% β) and insulin resistance were made from basal plasma glucose and insulin concentrations using a computer solved model. Fasting proinsulin levels provided an independent measure of β cell function. Results - The circadian rhythm of sympathovagal balance (ratio of low to high frequency spectral components of heart rate variability) was significantly attenuated in patients with below median (%β ≤ 63.3) compared with above median pancreatic β cell function. Multiple measures of autonomic function showed positive associations with %β (low frequency: r = 0.41, p = 0.004; high frequency: r = 0.27, p = 0.07; lying/standing fall in systolic pressure: r = -0.30, p = 0.04) and negative associations with proinsulin (low frequency: r = -0.35, p = 0.03; high frequency: r = -0.36, p = 0.02; standard deviation of RR intervals: r = -0.43, p = 0.007). Associations tended to be stronger in non-diabetic than diabetic patients. In contrast, there was no association between insulin resistance and either autonomic function or the circadian rhythm of sympathovagal balance, regardless of diabetes status. Conclusions - The data are consistent with the hypothesis that β cell failure plays a pathogenic role in the development of autonomic dysfunction in patients with coronary artery disease.