The gene MTNR1B encodes a receptor for melatonin. Melatonin receptors are expressed in human β-cells, which implies that genetic variants might affect glucose tolerance. Meta-analysis confirmed that the rs10830963 shows the most robust association. The aim of the study was to assess the rs10830963 in Czech GDM patients and controls and to study relations between the SNP and biochemical as well as anthropometric characteristics. Our cohort consisted of 880 women; 458 were diagnosed with GDM, and 422 were normoglycemic controls without history of GDM. Despite similar BMI, the GDM group showed higher WHR, waist circumference, abdominal circumference, and total body fat content. The risk allele G was more frequent in the GDM group (38.3 versus 29.4% in controls, OR 1.49 CI95% [1.22; 1.82]; P OR = 0.0001). In spite of higher frequency, the G allele in the GDM group was not associated with any markers of glucose metabolism. In contrast, controls showed significant association of the allele G with FPG and with postchallenge glycemia during the oGTT. Frequency analysis indicates that rs10830963 is involved in gestational diabetes in Czech women. However, the association of the SNP with glucose metabolism, which is obvious in controls, is covert in women who have experienced GDM.

Context Gestational diabetes mellitus (GDM) is accompanied by subclinical inflammation; however, little is known about local inflammation in adipose tissue and placenta. Objective To analyse systemic and local subclinical inflammation and adipose tissue lymphocyte content and phenotype in pregnant females with and without GDM. Design Observational study. Settings Academic hospital. Patients Twenty-one pregnant females with GDM (GDM group), 16 pregnant women without GDM (non-GDM group) and 15 non-pregnant control females (N group). Interventions Serum samples taken at 28-32 (V1) and 36-38 (V2) gestational week and 6-12 months after delivery (V3) in GDM and non-GDM group and before elective gynaecological surgery in N group. Subcutaneous (SAT) and visceral adipose tissue (VAT) obtained during Caesarean delivery or surgery. Main Outcome Measures Serum levels and adipose tissue expression of proinflammatory cytokines, adipose tissue lymphocyte content and phenotype (for a subset of GDM and non-GDM subjects). Results Accented proinflammatory state in GDM was documented by increased circulating TNF-α levels. In both groups of pregnant females total lymphocytes were higher in VAT compared to SAT. In GDM subjects B and NKT cells were higher in SAT compared to VAT and Th cells were increased relative to SAT of non-GDM group, while no intercompartmental adipose tissue differences were seen in non-GDM females. Conclusions Pregnant females had higher total lymphocyte count in VAT relative to SAT regardless of GDM. In addition to increased systemic subclinical inflammation, GDM was associated with significant differences in lymphocyte composition between subcutaneous and visceral adipose tissue depots.

We measured plasma concentrations, adipose tissue and placental mRNA expression of hepatokines fetuin A, fetuin B and fibroblast growth factor 21 (FGF21) in 12 healthy pregnant women (P group), 12 pregnant women with gestational diabetes (GDM) and 10 healthy non-pregnant women (N group) to explore their potential role in the etiopathogenesis of GDM. GDM and P group had comparable BMI, C-reactive protein (CRP) and glycated hemoglobin levels while IL-10 and TNF-α levels were higher in GDM group. Fetuin A and fetuin B levels were higher in pregnancy as compared to N group and decreased after delivery with no apparent influence of GDM. In contrast, the pattern of changes of circulating FGF21 levels differed between GDM and P group. Fetuin A concentrations positively correlated with CRP, TNF-α mRNA expression in adipose tissue and IL-6 mRNA expression in placenta. Fetuin B positively correlated with CRP. FGF21 levels correlated positively with IFN-γ mRNA in adipose tissue and inversely with IL-8 mRNA in the placenta. Taken together, fetuin A and fetuin B levels were increased during pregnancy regardless of the presence of GDM. In contrast, FGF21 patterns differed between healthy pregnant women and GDM patients suggesting a possible role of this hepatokine in the etiopathogenesis of GDM.

BackgroundThe MTNR1B gene encodes a receptor for melatonin, a hormone regulating biorhythms. Disruptions in biorhythms contribute to the development of type 2 diabetes mellitus (T2DM). Genetic studies suggest that variability in the MTNR1B gene affects T2DM development. Our aim was to compare the distribution of the genetic variant rs10830963 between persons differing in glucose tolerance in a sample of the Czech population (N=1206). We also evaluated possible associations of the polymorphism with insulin sensitivity, beta cell function, with the shape of glucose, insulin and C-peptide trajectories measured 7 times during a 3-hour oral glucose tolerance test (OGTT) and with glucagon response. In a subgroup of 268 volunteers we also evaluated sleep patterns and biorhythm.Results13 persons were diagnosed with T2DM, 119 had impaired fasting blood glucose (IFG) and/or impaired glucose tolerance (IGT). 1074 participants showed normal results and formed a control group. A higher frequency of minor allele G was found in the IFG/IGT group in comparison with controls. The GG constellation was present in 23% of diabetics, in 17% of IFG/IGT probands and in 11% of controls. Compared to CC and CG genotypes, GG homozygotes showed higher stimulated glycemia levels during the OGTT. Homozygous as well as heterozygous carriers of the G allele showed lower very early phase of insulin and C-peptide secretion with unchanged insulin sensitivity. These differences remained significant after excluding diabetics and the IFG/IGT group from the analysis. No associations of the genotype with the shape of OGTT-based trajectories, with glucagon or with chronobiological patterns were observed. However, the shape of the trajectories differed significantly between men and women.ConclusionIn a representative sample of the Czech population, the G allele of the rs10830963 polymorphism is associated with impaired early phase of beta cell function, and this is evident even in healthy individuals.