Sympathetic Transduction in Type 2 Diabetes Mellitus

Approximately 60% of patients with type 2 diabetes mellitus (T2D) develop hypertension. Recent work also indicates greater blood pressure (BP) excursions throughout the day in T2D. Collectively, these findings suggest altered BP control in T2D. Although muscle sympathetic nerve activity (MSNA) recordings in T2D have provided equivocal results, quantification of MSNA alone does not account for ensuing vasoconstriction and BP responses elicited by MSNA. Thus, we tested the hypothesis that patients with T2D exhibit enhanced sympathetic transduction to BP. MSNA (microneurography) and beat-to-beat BP (Finometer) were measured at rest in 21 T2D and 13 age-matched and body mass index–matched control subjects and, signal-averaging was performed to quantify the mean arterial pressure and total vascular conductance responses to spontaneous bursts of MSNA. The peak mean arterial pressure and total vascular conductance responses to spontaneous MSNA were similar between T2D and control (both P >0.05). However, further analysis, separating T2D into those taking statins (n=13, T2D +statin) and not taking statins (n=8, T2D −statin), indicated that T2D −statin patients (4.2±0.6 mm Hg) exhibited greater peak mean arterial pressure responses compared with both T2D +statin patients (2.5±0.3 mm Hg, P =0.01) and control (control: 2.8±0.3 mm Hg, P =0.02). Likewise, nadir total vascular conductance responses to spontaneous MSNA bursts were greater in T2D −statin patients (T2D −statin: −3.3±0.6 mL/(min·mm Hg), T2D +statin: −1.6±0.3 mL/(min·mm Hg), P =0.03; control −2.2±0.3 mL/(min·mm Hg), P =0.08). Notably, T2D +statin patients exhibited similar peak mean arterial pressure and total vascular conductance responses to MSNA compared with control. Collectively, these findings demonstrate, for the first time, that patients with T2D exhibit augmented sympathetic transduction and this effect seems to be offset by statin therapy.