Aims: To examine the association between cardiac autonomic neuropathy and hypertension and the role of this association in diabetic complications.
Methods: We included 310 patients, 138 with Type 1 and 172 with Type 2 diabetes, 62 of them with hypertension. Cardiac autonomic neuropathy was assessed by analysing heart rate variations during three standard tests (deep breathing, lying to standing and Valsalva) and looking for postural hypotension.
Results: Cardiac autonomic neuropathy was present in 123 patients and 39 also had hypertension. The prevalence of a cardiac autonomic neuropathy/hypertension association was higher in Type 2 patients (P < 0.002). The prevalence of hypertension increased with the severity of cardiac autonomic neuropathy. In multiple logistic regression analysis, cardiac autonomic neuropathy was an independent risk factor for hypertension [odds ratio 2.86 (1.54-5.32); P < 0.001]. Only confirmed or severe cardiac autonomic neuropathy (two or more abnormal function tests, respectively) were independent risk factors for hypertension (P < 0.005 and < 0.0001). Cardiac autonomic neuropathy was found in most of the patients with macrovascular complications, retinopathy or nephropathy, but a large majority of the patients with these complications exhibited the cardiac autonomic neuropathy/hypertension profile. This profile was more prevalent among the patients with coronary or peripheral artery disease or antecedent stroke than among those free of these complications (P < 0.001). In logistic regression analyses, the cardiac autonomic neuropathy/hypertension profile associated significantly with macro- and microvascular complications.
Conclusions: These data are strongly in favour of the role of cardiac autonomic neuropathy in hypertension in diabetic patients. The association of the cardiac autonomic neuropathy/hypertension profile with vascular complications is consistent with a deleterious effect on vascular hemodynamics and structure, additional to the effects of hypertension.