Glycaemic control, low levels of high-density lipoprotein, and high cardiovascular risk are associated with cardiovascular autonomic neuropathy.

Background: Cardiovascular autonomic neuropathy (CAN) is a life-threatening complication associated with diabetes but may also be present without diabetes. A glycaemic threshold for autonomic impairment is not yet established. The purpose of this study was to compare CAN status in people with and without diabetes and to investigate which factors contributed the most to the presence and severity of CAN.

Methods: We included 240 participants from three different cohorts: non-diabetic people (n = 40), people with overweight or obesity with or without prediabetes (n = 100), and people with type 2 diabetes (n = 100). All participants underwent cardiovascular autonomic reflex tests using the Vagus™ device, and clinical variables, including age, sex, body mass index, blood pressure, HbA1c, blood lipid profile, and cardiovascular risk score, were recorded.

Results: In total, 14% without and 42% with diabetes had CAN. HbA1c had the most significant influence on CAN scores, with a cutpoint of 45.5 mmol/l corresponding to established prediabetes (sensitivity: 0.66; specificity: 0.71). In people with HbA1c levels below the cutpoint, those with CAN had lower levels of high-density lipoprotein (HDL) (1.1 vs. 1.4 mmol/mol, p = 0.003) and higher cardiovascular risk scores (p < 0.001) compared to people without CAN. No differences in any of the investigated clinical factors were seen between people with HbA1c levels above the cutpoint with or without CAN.

Conclusions: In individuals with HbA1c levels below 45.5 mmol/l, both HDL levels and cardiovascular risk score were associated with CAN status. Therefore, it may be beneficial to screen for CAN in individuals susceptible to prediabetes, who also exhibit low HDL levels and a high cardiovascular risk.