Cardiovascular autonomic neuropathy and other complications in type 1 diabetes.

OBJECTIVE AND METHODS: This study deals with cardiovascular autonomic neuropathy (CAN) in type 1 diabetic patients and its association with other complications. We searched for CAN in 684 patients (age, 47 +/- 12 years; diabetes duration, 22 +/- 11 years) by cardiovascular responses to deep breathing and standing. Patients considered as positive had laboratory evaluation: "Ewing" tests (deep breathing, Valsalva, stand test, hand grip); heart rate variability (HRV) [low frequency (LF) and high frequency (HF) power] and spontaneous baroreflex slope (SBS). Logistic regression was used to identify the combination of patient characteristics, including other complications, most associated with CAN severity according to Ewing Score (ES 0-5).

RESULTS: 66.2% presented no significant abnormality (ES 0-0.5), 21.5 % had mild abnormalities (ES 1-2), and 12.3% had confirmed autonomic failure (ES > 2). Decrease in LF, HF and SBS was highly correlated to CAN severity. In the stepwise regression, age, retinopathy, nephropathy, bladder dysfunction, erectile dysfunction, peripheral neuropathy and hypertension remained correlated with CAN, whereas digestive neuropathy, BMI and HbA1c were excluded. Despite a small number of events, we found a significant association between coronary disorders and CAN severity.

CONCLUSIONS: Simple bedside tests can detect CAN. HRV and SBS provide additional elements on CAN severity. Diabetes duration did not discriminate sufficiently patients with CAN. The association with retinopathy is in favor of the role of poor glycemic control in CAN development. This study shows the interest of CAN detection and the need to look for extracardiac autonomic neuropathy and silent myocardial ischemia in patients with confirmed CAN.