Diabetes Impacts Adolescents’ Central and Peripheral Vascular Function During Exercise, Study Shows

   According to research reported on at ENDO 2011: the 93rd Annual Meeting & Expo of the Endocrine Society in Boston, type 2 diabetes (T2D) negatively affects both central and peripheral vascular function during exercise in adolescents, independent of obesity.

   Australian and American researchers sought to determine exercise capacity (VO2peak) in a group of adolescents with T2D compared with an obese, non-T2D group and a non-obese control group, assessing cardiac function with the use of cardiac MRI at rest and during sub-maximal exercise. A further goal was to assess femoral artery flow (FAF) at rest and immediately post-exercise as a marker of peripheral vascular function.

   Thirteen subjects with T2D, 27 overweight or obese subjects, and 19 non-diabetic, non-obese controls, aged 12 to 20 years, were recruited. All performed an incremental exercise test on a cycle ergometer. Body composition was determined using dual-energy x-ray absorptiometry (DEXA). Cardiac and femoral flow MRI images were taken at rest and during or immediately after sub-maximal exercise using a cycle ergometer designed for use in the MRI.

   The maximum heart rate (HR) achieved was higher in the control group than in the two other groups (P<0.01) despite comparable maximum workloads. There was no difference in cardiac output (CO) indexed for fat free mass (FFM) between groups at rest. However, during exercise CO/FFM was lower in the T2D compared to the obese and control groups (P<0.01, P<0.001 respectively). The researchers found that SV increased by 11.1% in the control group, 5.98% in the obese group, and 0.76% in the T2D group during exercise. End-diastolic volume (EDV)/FFM was significantly lower in the T2D both at rest and during exercise. During exercise, EDV decreased by 2.1% in the control group, 0.9% in the obese group, and 6.1 % in the T2D group. End-systolic volume (ESV)/FFM was lower in the T2D group at rest and during exercise compared to controls (P<0.01). The average FAF/minute and the net forward volume both indexed for FFM were significantly lower in the T2D group post exercise compared to the other two groups (P<0.05).

   The researchers concluded that the reduction in both central and peripheral vascular function during exercise in adolescents related to T2D appears to be secondary to impaired filling and possible diastolic dysfunction; peripheral blood flow to exercising muscles may also be impaired.