Aims: The G‐allele of the single nucleotide polymorphism (SNP) rs10830963 in MTNR1B (melatonin receptor 1B gene) is associated with type 2 diabetes mellitus and glucose levels in adults. The aim of this study was to analyze whether there is an allele‐dosage effect on glucose metabolism in overweight children and to explore if changes in glucose metabolism in a lifestyle intervention do also depend on genotype.
Methods: We genotyped rs10830963 in 1118 overweight children and adolescents [mean age 10.7 yr, mean body mass index (BMI) 27.8 kg/m2]; 340 of these individuals completed a 1‐yr lifestyle intervention (mean age 10.7 yr, mean BMI 27.9 kg/m2). The degree of overweight [BMI‐SDS (standard deviation score)], fasting insulin, glucose, homeostasis model assessment for insulin resistance (HOMA‐IR), and quantitative insulin sensitivity check index (QUICKI) were measured before and after intervention.
Results: We showed a significant relationship between rs10830963 and basal glucose levels [β:1.101, 95% confidence interval (CI) 0.316–1.886 mg/dL per risk allele; p = 0.006] by linear regression adjusted for age, age2, and sex. There was no effect of the allele on insulin or indices of insulin resistance or sensitivity. After the 1‐yr lifestyle intervention, we observed a significant reduction of BMI‐SDS as well as an improvement of HOMA‐IR and QUICKI, but no evidence for an association between rs10830963 genotype and changes of glucose levels.
Conclusions: The G‐allele of rs10830693 in the MTNR1B gene was significantly related to glucose levels, while an impact of this genetic variant on the changes in glucose metabolism in children participating in a lifestyle intervention was not observable.