Variation in the Plasma Membrane Monoamine Transporter (PMAT) (Encoded by ) and Organic Cation Transporter 1 (OCT1) (Encoded by ) and Gastrointestinal Intolerance to Metformin in Type 2 Diabetes: An IMI DIRECT Study.

Objective: Gastrointestinal adverse effects occur in 20-30% of patients with metformin-treated type 2 diabetes, leading to premature discontinuation in 5-10% of the cases. Gastrointestinal intolerance may reflect localized high concentrations of metformin in the gut. We hypothesized that reduced transport of metformin via the plasma membrane monoamine transporter (PMAT) and organic cation transporter 1 (OCT1) could increase the risk of severe gastrointestinal adverse effects.

Integrative network analysis highlights biological processes underlying GLP-1 stimulated insulin secretion: A DIRECT study.

Glucagon-like peptide 1 (GLP-1) stimulated insulin secretion has a considerable heritable component as estimated from twin studies, yet few genetic variants influencing this phenotype have been identified. We performed the first genome-wide association study (GWAS) of GLP-1 stimulated insulin secretion in non-diabetic individuals from the Netherlands Twin register (n = 126). This GWAS was enhanced using a tissue-specific protein-protein interaction network approach.

HbA is associated with altered expression in blood of cell cycle- and immune response-related genes.

Aims/hypothesis: Individuals with type 2 diabetes are heterogeneous in their glycaemic control as tracked by blood HbA levels. Here, we investigated the extent to which gene expression levels in blood reflect current and future HbA levels.

Methods: HbA levels at baseline and 1 and 2 year follow-up were compared with gene expression levels in 391 individuals with type 2 diabetes from the Hoorn Diabetes Care System Cohort (15,564 genes, RNA sequencing).

Metabolite ratios as potential biomarkers for type 2 diabetes: a DIRECT study.

Aims/hypothesis: Circulating metabolites have been shown to reflect metabolic changes during the development of type 2 diabetes. In this study we examined the association of metabolite levels and pairwise metabolite ratios with insulin responses after glucose, glucagon-like peptide-1 (GLP-1) and arginine stimulation. We then investigated if the identified metabolite ratios were associated with measures of OGTT-derived beta cell function and with prevalent and incident type 2 diabetes.

The Hoorn Diabetes Care System (DCS) cohort. A prospective cohort of persons with type 2 diabetes treated in primary care in the Netherlands.

Purpose: People with type 2 diabetes (T2D) have a doubled morbidity and mortality risk compared with persons with normal glucose tolerance. Despite treatment, clinical targets for cardiovascular risk factors are not achieved. The Hoorn Diabetes Care System cohort (DCS) is a prospective cohort representing a comprehensive dataset on the natural course of T2D, with repeated clinical measures and outcomes.

Variation in the glucose transporter gene SLC2A2 is associated with glycemic response to metformin.

Metformin is the first-line antidiabetic drug with over 100 million users worldwide, yet its mechanism of action remains unclear. Here the Metformin Genetics (MetGen) Consortium reports a three-stage genome-wide association study (GWAS), consisting of 13,123 participants of different ancestries. The C allele of rs8192675 in the intron of SLC2A2, which encodes the facilitated glucose transporter GLUT2, was associated with a 0.

The CTRB1/2 locus affects diabetes susceptibility and treatment via the incretin pathway.

The incretin hormone glucagon-like peptide 1 (GLP-1) promotes glucose homeostasis and enhances β-cell function. GLP-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors, which inhibit the physiological inactivation of endogenous GLP-1, are used for the treatment of type 2 diabetes. Using the Metabochip, we identified three novel genetic loci with large effects (30-40%) on GLP-1-stimulated insulin secretion during hyperglycemic clamps in nondiabetic Caucasian individuals (TMEM114; CHST3 and CTRB1/2; n = 232; all P ≤ 8.

Mineralocorticoid receptor gene variants as determinants of HPA axis regulation and behavior.

We tested if common mineralocorticoid receptor (MR) gene variants contribute to the variability in neuroendocrine control and behavioral reactivity as observed in humans. For that purpose we screened for genetic variability and tested functionality of the identified human MR gene variants in vitro. Four haplotypes were tested for transactivational capacity in vitro and showed profound significant differences when stimulated with cortisol.

Human mineralocorticoid receptor (MR) gene haplotypes modulate MR expression and transactivation: implication for the stress response.

Stress causes activation of the hypothalamic-pituitary-adrenal (HPA) axis, resulting in secretion of corticosteroids which facilitate behavioural adaptation. These effects exerted by corticosteroids are mediated by two brain corticosteroid receptor types, the mineralocorticoid receptor (MR), with a high affinity already occupied under basal conditions and the glucocorticoid receptor (GR), with a low affinity only activated during stress. Here, we studied MR gene haplotypes constituted by the two single nucleotide polymorphisms MR-2G/C (rs2070951) and MRI180V (rs5522).

The functional c.-2G>C variant of the mineralocorticoid receptor modulates blood pressure, renin, and aldosterone levels.

The mineralocorticoid receptor (MR) is essential in the regulation of volemia and blood pressure. Rare mutations in the MR gene cause type 1 pseudohypoaldosteronism and hypertension. In this study we characterized the common MR polymorphism c.

Functional mineralocorticoid receptor (MR) gene variation influences the cortisol awakening response after dexamethasone.

Stress causes activation of the hypothalamic-pituitary-adrenal (HPA) axis and results in the secretion of corticosteroids, which facilitate behavioral adaptation and promote the termination of the stress response. These actions exerted by cortisol are mediated by two brain corticosteroid receptor types: the high affinity mineralocorticoid (MR) and the low affinity glucocorticoid receptor (GR). Dexamethasone is a potent GR agonist with affinity to MR.

Corticosteroid receptor-gene variants: modulators of the stress-response and implications for mental health.

The stress-response, including autonomic and hypothalamic-pituitary-adrenal (HPA) axis reactivity, is essential for maintaining homeostasis during a challenge. Brain mineralocorticoid receptors and glucocorticoid receptors operate in balance to coordinate the stress-response. Genetic variants in both the human mineralocorticoid and glucocorticoid receptor-genes have been functionally characterized.