Effects of therapeutic ultrasound on the endothelial function of patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by endothelial dysfunction that causes micro- and macrovascular complications. Low intensity therapeutic ultrasound (LITUS) may improve endothelial function, but its effects have not been investigated in these patients. The aim of our study was to compare the effects of pulsed (PUT) and continuous (CUT) waveforms of LITUS on the endothelium-dependent vasodilation of T2DM patients. The present randomized crossover trial had a sample of twenty-three patients (7 men) diagnosed with T2DM, 55.6 (±9.1) years old, with a body mass index of 28.6 (±3.3) kg/m2. All patients were randomized and submitted to different waveforms (Placebo, CUT, and PUT) of LITUS and the arterial endothelial function was evaluated. The LITUS of 1 MHz was applied in pulsed (PUT: 20% duty cycle, 0.08 W/cm2 SATA), continuous (CUT: 0.4 W/cm2 SPTA), and Placebo (equipment off) types of waves during 5 min on the brachial artery. Endothelial function was evaluated using the flow-mediated dilation (FMD) technique. PUT (mean difference 2.08%, 95% confidence interval 0.65 to 3.51) and CUT (mean difference 2.32%, 95% confidence interval 0.89 to 3.74) increased the %FMD compared to Placebo. In the effect size analysis, PUT (d=0.65) and CUT (d=0.65) waveforms presented moderate effects in the %FMD compared to Placebo. The vasodilator effect was similar in the different types of waves. Pulsed and continuous waveforms of LITUS of 1 MHz improved the arterial endothelial function in T2DM patients.

Effects of respiratory muscle training on parasympathetic activity in diabetes mellitus

This study verified the effects of respiratory muscle training (RMT) on hemodynamics, heart rate (HR) variability, and muscle morphology in rats with streptozotocin-induced diabetes mellitus (DM). Thirty-six male Wistar rats were randomized into 4 groups and 34 completed the study: i) sham-sedentary (Sham-ST; n=9); ii) sham-RMT (Sham-RMT; n=9); iii) DM-sedentary (DM-ST; n=8); and iv) DM-RMT (DM-RMT; n=8). Hemodynamics were assessed by central cannulation, and R-R intervals were measured by electrocardiogram. In addition, the effects of RMT on the cross-sectional area of the diaphragm, anterior tibial, and soleus muscles were analyzed. The induction of DM by streptozotocin resulted in weight loss, hyperglycemia, reduced blood pressure, and attenuated left ventricular contraction and relaxation (P<0.05). We also observed a decrease in root mean square of successive differences between adjacent RR intervals (RMSSD) index and in the cross-sectional area of the muscles assessed, specifically the diaphragm, soleus, and anterior tibial muscles in diabetic rats (P<0.05). Interestingly, RMT led to an increase in RMSSD in rats with DM (P<0.05). The induction of DM produced profound deleterious changes in the diaphragmatic and peripheral muscles, as well as impairments in cardiovascular hemodynamics and autonomic control. Nevertheless, RMT may beneficially attenuate autonomic changes and improve parasympathetic modulation.