A group of investigators led by Dr Seung-Hyun Ko of The Catholic University of Korea in Seoul, Korea, have conducted a study to determine whether cardiovascular autonomic dysfunction is associated with glycaemic control in patients with type 2 diabetes. A total of 1,021 patients with type 2 diabetes underwent cardiovascular autonomic nerve function (AFT) testing between 1999 and 2000, with follow-up in 2006 and 2008. Patients were assigned AFT scores (which measure heart rate variability parameters including expiration-to-inspiration [E/I] ratio, response to Valsalva manoeuvre, and standing/posture) of either 0 for normal function or 1 for abnormal function. A total of 783 patients with normal function scores were assessed for total score changes and biannual HbA1c levels over a period of 7.5 years.

The investigators found that 34.5% of patients showed cardiovascular autonomic dysfunction at follow-up (abnormal results for E/I ratio in 21.9%, for Valsalva manoeuvre in 77.8%, and for standing/posture in 58.9%). The group determined that, based on logistic regression analysis, the development of cardiovascular autonomic dysfunction was associated with HBA1c level during the follow-up period (odds ratio 2.984, p = 0.021). The development of cardiovascular autonomic dysfunction was also significantly higher in older patients, and those with longer duration of diabetes, hypertension, diabetic retinopathy, and higher levels of microalbuminuria.

The investigators concluded that the development of cardiovascular autonomic dysfunction is strongly associated with microvascular complications and glycaemic control status.

Diabetes Care. 2008;31:1832-6.