Abstract
Aim/hypothesis
This study was designed to determine whether type 2 diabetic adolescents have reduced aerobic capacity and to investigate the role of cardiac output and arteriovenous oxygen difference (a−vO
2
) in their exercise response.
Methods
Female adolescents (age 12–18 years) with type 2 diabetes mellitus (
n
= 8) and type 1 diabetes mellitus (
n
= 12) and obese (
n
= 10) and non-obese (
n
= 10) non-diabetic controls were recruited for this study. Baseline data included maximal aerobic capacity (cycle ergometer) and body composition. Cardiac output and a−vO
2
were determined at rest and during submaximal exercise.
Results
Diabetic groups had lower aerobic capacity than non-diabetic groups (
p
< 0.05). Adolescents with type 2 diabetes had lower aerobic capacity than the type 1 diabetic group. Maximal heart rate was lower in the type 2 diabetic group (
p
< 0.05). Exercise stroke volume was 30–40% lower at 100 and 120 beats per min in the diabetic than in the non-diabetic groups (
p
< 0.05). The a−vO
2
value was not different in any condition.
Conclusions and interpretation
Type 2 diabetic adolescents have reduced aerobic capacity and reduced heart rate response to maximal exercise. Furthermore, type 2 and type 1 diabetic adolescent girls have a blunted exercise stroke volume response compared with non-diabetic controls. Central rather than peripheral mechanisms contribute to the reduced aerobic capacity in diabetic adolescents. Although of short duration, type 2 diabetes in adolescence is already affecting cardiovascular function in adolescents.