B-28 Free Communication/Poster - Cardiovascular I Wednesday, June 1, 2016, 1: 00 PM - 6: 00 PM Room: Exhibit Hall A/B
Cardiac autonomic dysfunction reduces cardiac reserve in neuropathic patients with diabetes. People with uncomplicated diabetes also have reduced cardiac reserve, but the influence of cardiac autonomic (dys) function has not been identified in these people.
PURPOSE: To determine whether people with uncomplicated type 2 diabetes have reduced chronotropic and inotropic responses to β-adrenergic stimulation.
METHODS: 8 people with uncomplicated type 2 diabetes (T2D) and 7 matched controls (CON) performed a V[Combining Dot Above]O2max test (with ECG) and DEXA scan. On a second visit, heart rate (HR), left ventricular end-diastolic (EDV), end-systolic (ESV), stroke volume (SV) and cardiac output (Q[Combining Dot Above]) were measured with echocardiography during supine rest, parasympathetic blockade (atropine), and during incremental β-adrenergic stimulation (dobutamine). All volumes were indexed to fat free mass (FFM). Data were analysed with linear mixed models and students t-tests.
RESULTS: V[Combining Dot Above]O2max and heart rate (HR) reserve were lower in T2D (P < 0.05) as expected. At rest, HR was higher (P < 0.01) and stroke volume (SVFFM) was smaller (P < 0.05) in T2D but cardiac output (Q[Combining Dot Above]FFM) and ejection fraction (EF) were not different between the groups. After parasympathetic blockade, HR (112 ± 8 vs. 105 ± 8 beats.min−1; P = 0.08) and the increase in HR (ΔHR) were not different (39 ± 8 vs. 45 ± 9; P = 0.22) between the groups. HR was greater in T2D during dobutamine infusion (P < 0.05), but ΔHR (interaction) was not different between groups.T2D achieved 85% maximal HR at a lower dobutamine dose than CON (11 ± 4 vs. 20 ± 10 μkg−1 min−1; P < 0.05). EDVFFM was lower (P < 0.05) during β-adrenergic stimulation in T2D but ESVFFM was not different between groups. Ejection fraction increased (P < 0.05) equally in both groups during β-adrenergic stimulation and SVFFM decreased in T2D but increased in CON (P < 0.05). Q[Combining Dot Above]FFM increased in CON but did not change in T2D during β-adrenergic stimulation (P < 0.05).
CONCLUSIONS: HR is increased and SVFFM is reduced in T2D at rest and during β-adrenergic stimulation. EF and ESVFFM were not different during β-adrenergic stimulation, but EDVFFM and SVFFM were smaller in T2D. These data indicate that reduced β-adrenergic responsiveness does not contribute to reduced cardiac reserve in uncomplicated type 2 diabetes during submaximal stress.