Could we predict asymptomatic cardiovascular autonomic neuropathy in type 1 diabetic patients attending out-patients clinics?

Background And Aims: Diabetic cardiovascular autonomic neuropathy (CAN) is associated with increased morbidity and mortality. This complication may be asymptomatic for a long time. The aim of this study was to assess the prevalence, severity and predictors of asymptomatic CAN in patients with type 1 diabetes mellitus (DM1).

Patients And Methods: 107 patients with DM1 were enrolled: 52 men and 55 women aged 39.8 +/- 12.4 years (18-72), duration of DM 16.6 +/- 9.5 years (0.5-43), age at DM manifestation 23.5 +/- 12.8 years (1-54) and BMI 25.1 +/- 3.2 (18.9-33.91). CAN was assessed using standard cardiovascular reflex tests (Ewing battery) and the patients were divided into three groups according to the results: Group 0, without CAN; Group I, 1(st) degree CAN; Group II, 2(nd) degree CAN. We assessed the most frequent relationships between CAN and chronic complications, episodes of severe hypoglycemia, time-related parameters (age of patients, duration of diabetes, age at manifestation), glycosylated hemoglobin (HbA(1)c), BMI, cardiovascular diseases and blood pressure, and determined the predictability of CAN on the basis of these relationships.

Results: Only 50 of the 107 patients (46%) showed no CAN. We found 1(st) degree CAN in 38 patients (36%) and 2(nd) degree CAN in 19 (18%). CAN correlated more significantly with the duration of diabetes (p < 0.001) than with age (p < 0.05). The relationship between CAN and HbA(1)c was on the borderline of statistical significance (p = 0.053). We found a positive correlation between CAN and the presence of chronic complications [peripheral neuropathy (p < 0.001), retinopathy (p < 0.001), and some markers of nephropathy: creatinine (p < 0.03), albuminuria (p < 0.01)]. Although blood pressure was within the physiological range (124.2/74.5 +/- 11.5/7.8 mmHg) in all patients, a positive correlation with CAN was confirmed (p < 0.05). No relationship with occurrence of severe hypoglycemia was found.

Conclusions: According to our results, asymptomatic CAN is very frequent in patients with DM1. By using multifactorial logistic regression (step-wise) analysis we demonstrated that if albuminuria, peripheral neuropathy and elevated systolic BP are present simultaneously, there is a high probability that the patient also has CAN (84.9% of initial group correctly predicted, p < 0.001).