Irisin and Its Relation to Insulin Resistance and Puberty in Obese Children: A Longitudinal Analysis

• Published in: The journal of clinical endocrinology and metabolism 2015-05, Vol.100 (5), p.2123-2130
• Main Authors: Reinehr, Thomas, Elfers, Clinton, Lass, Nina, Roth, Christian L
• Format: Article
• Language: English
• Subjects: Adolescent; Blood Glucose - metabolism; Blood pressure; Blood Pressure - physiology; Body Mass Index; Body weight loss; Child; Children; Cholesterol; Fasting; Female; Fibronectins - blood; Follow-Up Studies; Gender; Glucose; Glucose tolerance; Glucose Tolerance Test; High density lipoprotein; Homeostasis; Humans; Insulin - blood; Insulin resistance; Insulin Resistance - physiology; Laboratory testing; Lipid metabolism; Longitudinal Studies; Male; Metabolic syndrome; Nutrition therapy; Obesity; Obesity - blood; Obesity - metabolism; Obesity - therapy; Primary care; Puberty; Puberty - blood; Weight Loss - physiology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2015-1208

Context: Irisin is a recently identified myokine affecting metabolic and glucose homeostasis. However, the role of irisin in obesity and its metabolic consequences are controversial, and data in children are scarce. Objective: To study the relationships between irisin, insulin resistance, and puberty before and after weight loss in obese children with and without impaired glucose tolerance. Design: One-year follow-up study in obese children participating in a lifestyle intervention. Setting: Primary care. Patients: Forty obese children and 20 normal-weight children of similar age, gender, and pubertal stage. Intervention: A 1-year outpatient intervention program based on exercise, behavior, and nutrition therapy. Main Outcomes Measures: Fasting serum irisin, weight status (body mass index [BMI] SD score), and the following parameters of the metabolic syndrome: insulin resistance index (homeostasis model of assessment), blood pressure, and lipids. Results: The irisin levels were the highest in obese children with impaired glucose tolerance, followed by obese children with normal glucose tolerance, and levels were lowest in normal-weight children (P < .001). In a multiple linear regression analysis, baseline irisin was significantly associated with pubertal stage, high-density lipoprotein-cholesterol, and homeostasis model of assessment, but not to age, gender, BMI, or any other parameter of the metabolic syndrome. The irisin concentrations were significantly (P = .010) lower in the prepubertal compared to the pubertal children. In longitudinal analyses, changes of irisin were significantly associated with entry into puberty, change of fasting glucose, and 2-hour glucose in an oral glucose tolerance test, but not with change of BMI or any other parameter. Conclusions: Irisin levels are related to pubertal stage and insulin resistance but not to weight status in childhood.