Baroreflex sensitivity assessment in patients with type 2 diabetes during orthostatic challenge

Background: Type 2 diabetes (DM) is characterized by hyperglycemia, insulin resistance and variable degree of insulin secretory deficiency. Individuals with DM may develop autonomic dysfunction that can be evaluated by baroreflex sensitivity (BRS). Objective: to evaluate baroreflex sensitivity (BRS) in patients with DM compared to control group. Methods: We enrolled 34 patients with DM without cardiovascular neuropathy and 34 healthy subjects (CG). The two groups were age matched. Electrocardiogram and noninvasive finger arterial pressure signals were recorded and sampled at 1 KHz. Each experimental session consisted of 15 minutes at rest (REST) followed by 15 minutes of standing (STAND). Consecutive 256 R-R intervals and systolic arterial pressure peaks were extracted through an automatic software. Time domain assessment of BRS was based on baroreflex sequence that relies on the search for sequences with length of four beats characterized by the contemporaneous increase or decrease of RR and SAP. The slope of the regression line was calculated, averaged over all BRS and was taken as a measure of BRS. Two-way Repeated Measures ANOVA test (One Factor Repetition) was performed. Statistical significance was defined as p < 0.05. Results: BRS decreased during STAND (5.98 ± 4.87, 3.99 ± 2.81; CG vs. DM) compared to REST (12.32 ± 9.23, 7.02 ± 5.52; CG vs. DM) in both groups. Furthermore, the DM patients showed a significant lower values of BRS in both experimental sessions compared to CG ones. Conclusions: Although the DM group reacted to postural change the BRS was reset to lower values indicating an impairment of baroreflex control. Financial Support: CAPES/CSF/PVE no. 23038.007721/2013-41; FAPESP n^os. 2010/52070-4 and 2013/07953-3.