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Circadian metabolic rhythms in obese children
Insights
Obese children often have high insulin levels and may overeat. This study found that obese children lack normal daily metabolic rhythms, unlike their non-obese peers.
Area of Science:
- Pediatric Endocrinology
- Metabolic Research
- Chronobiology
Background:
- Obesity in children is often associated with hyperinsulinism and hyperphagia.
- Hypothalamic system lesions in animals impact circadian rhythms of insulin secretion and food intake.
- Understanding metabolic rhythms in pediatric obesity is crucial.
Purpose of the Study:
- To investigate circadian metabolic rhythms in obese versus non-obese children.
- To compare glucose, insulin, and related metabolic responses throughout the day in both groups.
Main Methods:
- Two protocols were used: Oral Glucose Tolerance Tests (OGTT) at 9 a.m. and 3 p.m. on consecutive days.
- Determination of circadian variations in plasma glucose and insulin levels.
- Assessment of free fatty acid, growth hormone, and cortisol responses.
Main Results:
- Control children exhibited a significant drop in the insulin/glucose ratio in the afternoon, unlike obese children.
- Obese children maintained a high insulin/glucose ratio throughout the day without significant change.
- Circadian rhythm for blood glucose levels was observed in control children but absent in the obese group.
Conclusions:
- Obese children appear to have impaired metabolic rhythms.
- These findings suggest potential dysregulation within the hypothalamic system in pediatric obesity.
- Further research is warranted to explore the hypothalamic system's role in childhood obesity.
Abstract:
Obese children display constant hyperinsulinism and, frequently, hyperphagia. In animals, lesions of the hypothalamic system affect simultaneously the circadian rhythm of insulin secretion and of food intake. In this study, circadian metabolic rhythm was examined in obese and non-obese children, by two different protocols. (1) Oral glucose tolerance tests (OGTT) were carried out at 9 a.m. and 3 p.m. on 2 consecutive days. (2) Circadian variations of plasma glucose and insulin were determined. After OGTT, in the control children there was a significant drop in the insulin/glucose ratio in the afternoon, whereas in the obese group this ratio remained high, with no significant change during the day. Differences were also observed in free fatty acid, growth hormone, and cortisol responses. The control children showed a circadian rhythm for blood glucose levels which was not present in obesity. These preliminary data suggest impairment of metabolic rhythms in obese children; they should stimulate further studies on the hypothalamic system in obesity.