Cardiovascular autonomic neuropathy in insulin‐dependent diabetes mellitus: prevalence and estimated risk of coronary heart disease in the general population

Abstract. May O, Arildsen H, Damsgaard EM, Mickley H (Odense University Hospital, Odense, and Horsens Hospital, Horsens, Denmark). Cardiovascular autonomic neuropathy in insulin‐dependent diabetes mellitus: prevalence and estimated risk of coronary heart disease in the general population. J Intern Med 2000; 248: 483–491. Objectives. The aim of the study was to estimate the prevalence of cardiovascular autonomic neuropathy (CAN) in Type 1 diabetes mellitus in the general population and to assess the relationship between CAN and risk of future coronary heart disease (CHD). Methods. The Type 1 diabetes mellitus population in the municipality of Horsens, Denmark, was delineated by the prescription method and a random sample of 120 diabetics aged 40–75 years was recruited. Type 1 diabetes mellitus was registered if fasting C‐peptide was below 0.30 nmol L −1 . The E/I ratio was calculated as the mean of the longest R–R interval in expiration divided by the shortest in inspiration during deep breathing at 6 breaths min −1 and taken to express the degree of CAN. A maximal symptom‐limited exercise test was carried out and the VA Prognostic Score, indicating risk of cardiovascular death or non‐fatal myocardial infarction, was computed. Additionally, the 10‐year risk of CHD was calculated using the Framingham model. Results. A total of 84 people responded, of whom 71 had Type 1 diabetes mellitus. The E/I ratio was measured in 69 people. The prevalence of CAN expressed as an E/I ratio below the normal 5th percentile was 38%. The E/I ratio was significantly reduced in old age, long duration of diabetes, female gender, high fasting blood glucose, triglyceride, systolic blood pressure and urinary albumin excretion. A high risk of future CHD calculated using the Framingham model was associated with a low E/I ratio ( r = − 0.39, P = 0.001). Exercise capacity, rise in systolic blood pressure and heart rate were positively correlated with the E/I ratio. A high VA Prognostic Score was correlated with a low E/I ratio ( r = − 0.58, P < 0.0005). The risks estimated by the two models were significantly correlated ( r = 0.60, P < 0.0005). Conclusion. The prevalence of CAN in the 40–75‐year‐old Type 1 diabetes mellitus population is estimated to be 38%. CAN is associated with exercise test parameters and a coronary risk factor profile indicating a high risk of future CHD.