Insulin sensitivity among obese children and adolescents, according to degree of weight loss.

OBJECTIVE: Insulin sensitivity is impaired among some obese children, reflecting an atherogenic risk factor profile for the affected subjects. This study was performed to examine the amount of weight reduction required to improve insulin sensitivity.

METHODS: We studied changes in insulin sensitivity indices (ISIs) for glucose metabolism (homeostasis model assessment and quantitative insulin sensitivity check index) and fat metabolism (free fatty acids) during a 1-year period among obese children who attended an obesity intervention program. The children were divided into 4 groups according to their changes in body mass index (BMI) SD score (SDS), as follows: group I, decrease in SDS-BMI of > or =0.5; group II, decrease in SDS-BMI of > or =0.25 to <0.5; group III, decrease in SDS-BMI of <0.25; group IV, increase in SDS-BMI.

RESULTS: Fifty-seven obese children (age range: 6-14 years; median age: 10 years; 46% boys) were included in the study. The 4 groups did not differ with respect to age, gender, degree of overweight (SDS-BMI), or ISI values at baseline. An increase in SDS-BMI (group IV, n = 12) was followed by a significant decrease in ISI values. The ISIs improved for group I (n = 9), whereas there were no significant changes in these parameters for group II (n = 21) and group III (n = 15).

CONCLUSIONS: During a 1-year period, an increase in weight among obese children was associated with a decrease in insulin sensitivity. Weight loss was followed by significant improvement in insulin sensitivity for glucose and fat metabolism but only if the SDS-BMI decreased by > or =0.5 during the 1-year period.