Exercise training improves vascular function in adolescents with type 2 diabetes.

The impact of exercise training on vascular health in adolescents with type 2 diabetes has not been previously studied. We hypothesized that exercise training would improve micro- and macrovascular health in adolescents with type 2 diabetes. Thirteen adolescents (13-21 years, 10F) with type 2 diabetes were recruited from Princess Margaret Hospital. Participants were randomized to receive either an exercise program along with standard clinical care (n = 8) or standard care alone (n = 5). Those in the intervention group received 12 weeks of gym-based, personalized, and supervised exercise training. Those in the control group were instructed to maintain usual activity levels. Assessments were conducted at baseline and following week 12. The exercise group was also studied 12 weeks following the conclusion of their program. Assessments consisted of conduit artery endothelial function (flow-mediated dilation, FMD) and microvascular function (cutaneous laser Doppler). Secondary outcomes included body composition (dual-energy X-ray absorptiometry, DXA), glycemic control (whole body insulin sensitivity, M) assessed using the euglycemic-hyperinsulinemic clamp protocol, cardiorespiratory fitness (V˙O2peak), and muscular strength (1RM). Exercise training increased FMD (P < 0.05), microvascular function (P < 0.05), total lean mass (P < 0.05), and muscle strength (P < 0.001). There were no changes in cardiorespiratory fitness, body weight, BMI, or M. In the control group, body weight (P < 0.01), BMI (P < 0.01), and total fat mass (P < 0.05) increased. At week 24, improvements in vascular function were reversed. This study indicates that exercise training can improve both conduit and microvascular endothelial function and health, independent of changes in insulin sensitivity in adolescents with type 2 diabetes.

Endothelial function and carotid intima-medial thickness in adolescents with type 2 diabetes mellitus.

OBJECTIVE: We assessed the effect of type 2 diabetes mellitus and obesity on flow-mediated dilation (FMD) and endothelial-dependent vasodilation and carotid intima-medial thickness (cIMT) in young people. STUDY DESIGN: Adolescents were recruited in 3 groups: subjects with type 2 diabetes mellitus (n = 15), subjects who were obese and non-insulin resistant (n = 13), and lean control subjects (n = 13). Body mass index was similar in subjects with obesity and subjects with type 2 diabetes mellitus, but higher compared with that of lean control subjects (both P < .001). Brachial artery FMD and cIMT were assessed by using Duplex ultrasound scanning imaging. RESULTS: There were no significant differences in brachial or common carotid arterial diameters in the groups. cIMT was significantly greater in the group with type 2 diabetes mellitus (0.54 ± 0.01mm) compared with both the lean control (0.46 ± 0.02 mm, P < .001) and obese control (0.46 ± 0.02 mm, P < .01) groups. FMD was significantly decreased in the group with type 2 diabetes mellitus (7.98% ± 0.54%) compared with the lean group (10.40% ± 1.00%, P < .05). CONCLUSIONS: Measures of vascular health were impaired in adolescents with type 2 diabetes mellitus compared with lean and obese adolescents who were not insulin resistant. Measures of arterial function and structure may provide pre-clinical measures of cardiovascular disease in young people at elevated risk.