Risk factors for cardiac autonomic neuropathy in type 1 diabetes mellitus

Cardiac autonomic neuropathy (CAN) is associated with increased morbidity and mortality in type 1 diabetes. Apart from glycaemic control, risk factors for CAN have not been extensively studied.

As part of the EURODIAB Prospective Complications Study, CAN—defined as either a loss of heart rate variability or postural hypotension on standing—was assessed at baseline and follow-up (7.3±0.6 years from baseline) in patients with type 1 diabetes.

Follow-up measurements were available for 956 participants without CAN at baseline (age at baseline 31.3±8.9 years, duration of diabetes 13.5±8.3 years). During follow-up, 163 (17%) subjects developed CAN, yielding an incidence of 23.4 per 1,000 person-years. Blood pressure, weight, the presence of cardiovascular disease, albuminuria, distal symmetrical polyneuropathy (DSP) and retinopathy at baseline were associated with the incidence of CAN after adjustment for sex, duration of diabetes and HbA₁c. In a multivariate regression model, baseline factors associated with an increased risk of developing CAN were age [odds ratio (OR)=1.3 per decade, 95% CI 1.1–1.7], HbA₁c (OR=1.2 per percentage point, 95% CI 1.1–1.4), systolic blood pressure (OR=1.1 per 10 mmHg, 95% CI 1.0–1.3), feeling faint on standing (OR=2.0, 95% CI 1.2–3.2), DSP (OR=1.9, 95% CI 1.2–3.0) and retinopathy (OR=1.7, 95% CI 1.1–2.6).

This study confirms the importance of exposure to hyperglycaemia as a risk factor for CAN. A small set of variables, including HbA₁c, hypertension, DSP and retinopathy, predict the risk of CAN. Clinical trials are needed to address the impact of intensive antihypertensive treatment on CAN in type 1 diabetes.