The majority of schoolchildren with asthma do not participate in regular physical activity due to a risk of exercise-induced asthma. The aim of the study was to determine the glycemic characteristic of Taiwanese children with persistent asthma. The current study found that children with asthma (age 10.4 ± 0.4 years) exhibited lower whole-body insulin sensitivity and poorer physical fitness compared to children without asthma (age 10.9 ± 0.6 years). Postprandial glucose and insulin, BMI, and waist circumference of the children with asthma were greater than those of the healthy children. Four patients with asthma regularly participating in a permissible amount of physical activity exhibited lower postprandial glucose and insulin levels compared to those of the rest of the children with asthma who were totally lacking physical activity. A permissible amount of physical activity appears to be beneficial for children with asthma in the prevention of the early onset of insulin resistance.