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

Abstract

To assess the role of beta cell failure in the development of autonomic dysfunction in patients with coronary artery disease. 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 beta cell function (%beta) 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 beta cell function. 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 (%beta </= 63. 3) compared with above median pancreatic beta cell function. Multiple measures of autonomic function showed positive associations with %beta (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. The data are consistent with the hypothesis that beta cell failure plays a pathogenic role in the development of autonomic dysfunction in patients with coronary artery disease.