Gravity of diabetes and parasympathetic influences on heart rate variability during supine rest, forced breathing and mental

Purpose: The objective of the present study is to evaluate how gravity of diabetes influences parasympathetic control of heart rate variability and to compare different methods and conditions of evaluation. Methods: Subjects were 50 males, 20-50 years of age, where 38 had IDDM and 12 were without diabetes. Gravity of diabetes was based on it's duration, as well as levels of microalbuminuria and HbAl. Parasympathetic influences were indexed by: a) spectral power of the high frequency band (HF) at rest, b) forced breathing with 6 breaths/min used to calculate minimum and maximum heart rate (FBHRV), and c) cognitive challenge based on responding to an orbit crossing a screen of a computer, with 5 s intervals, giving transient heart rate deceleration (HRD). Results: Gravity of diabetes, including microalbuminuria, HbAl and duration of diabetes, was positively associated with FBHRV (p 0. 001). Duration of diabetes alone was negatively associated with HF (p = 0. 04). Duration of diabetes and microlabuminuria were positively related to HRD (p = 0. 002). There was a non-significant correlation between HF and FBHRV (r = -0. 1), FBHRV and HRD (r = 0. 4) and between HF and HRD (r = -0. 4). Conclusions: It is concluded that despite of the attenuation of parasympathetic influences at rest, it is possible to see exaggerated responses during activated states, like during forced breathing and cognitive challenge. The results are discussed in light of possible relation to fatal arrhytmias and sudden cardiac death among diabetics.