One-third of patients with diabetes had cardiovascular autonomic dysfunction

An association was reported among glycemic control, microvascular complications and cardiovascular autonomic dysfunction during a 7.5-year follow-up study in patients with type 2 diabetes.

These findings suggested monitoring of cardiovascular autonomic dysfunction and potential cardiovascular complications in both symptomatic and asymptomatic patients, according to researchers in Seoul, Korea.

In the study patients with type 2 diabetes (n=1,021) underwent cardiovascular autonomic nerve function testing from 1999 to 2000 with follow-up testing in 2006 and 2008. Autonomic nerve function testing scores were determined from test results — patients received a score of 0 for a normal test and a score of 1 for an abnormal test.

Follow-up revealed that 270 patients (34.5%) had abnormal autonomic nerve function testing scores. Among patients with newly diagnosed diabetes (n=133), 43 (32.3%) had abnormal autonomic nerve function test scores. Older patients and patients with a longer duration of diabetes, hypertension, retinopathy and higher levels of microalbuminuria were more likely to develop cardiovascular autonomic dysfunction, according to the researchers.

Cardiovascular autonomic dysfunction was strongly associated with mean HbA1c level during follow-up (>9% vs. ≤7%; OR=2.984; 95% CI, 1.177-7.561).

“Prolonged exposure to uncontrolled hyperglycemic conditions could predict future cardiovascular autonomic dysfunction, independent of the duration of diabetes among patients at baseline,” the researchers wrote. – by Katie Kalvaitis

Diabetes Care. 2008;31:1832-1836.

The finding that risk for autonomic dysfunction develops as a result of poor glycemic control and is independent of other cardiovascular risk factors is an important observation. The almost threefold greater risk for autonomic dysfunction present in those with an HbA1c >9% clearly indicates that high glucose concentration causes nerve injury. These findings argue for aggressive glycemic control to reduce morbidity. If autonomic dysfunction can be delayed or prevented, other cardiovascular risk factors, such as hypertension, will be easier to manage as well.

– George Bakris, MD

Endocrine Today Editorial Board member