Limits of clinical tests to screen autonomic function in diabetes type 1

Objectives: A precocious detection of cardiac autonomic dysfunction is of m ajor clinical interest that could lead to a more intensive supervision of d iabetic patients. However, classical clinical exploration of cardiac autono mic function is not easy to undertake in a reproducible way. Thus, respecti ve interests of autonomic nervous parameters provided by both clinical test s and computerized analysis of resting blood pressure were checked in type 1 diabetic patients without orthostatic hypotension and microalbuminuria. Material and methods: Thirteen diabetic subjects matched for age and gander to thirteen healthy subjects volunteered to participate to the study. From clinical tests (standing up, deep breathing, Valsalva maneuver, handgrip t est), autonomic function was scored according to Ewing's methodology. Analy sis of resting beat to beat blood pressure provided autonomic indices of th e cardiac function (spectral analysis or Z analysis). Results: 5 of the 13 diabetic patients exhibited a pathological score (more than one pathological response) suggesting the presence of cardiovascular autonomic dysfunction. The most discriminative test was the deep breathing test. However, spectral indices of BP recordings and baroreflex sensitivity (BRS) of these 5 subjects were similar to those of healthy subjects and of remaining diabetic subjects. Conclusion: Alteration in Ewing's score given by clinical tests may not ref lect an alteration of cardiac autonomic function in asymptomatic type I dia betic patients, because spectral indices of sympathetic and parasympathetic (including BRS) function were within normal range. Our results strongly su ggest to confront results provided by both methodologies before concluding to an autonomic cardiac impairment in asymptomatic diabetic patients.