Search

Pancreatic [beta] cell dysfunction is a key feature of type 2 diabetes, and novel regulators of insulin secretion are desirable. Here, we report that succinate receptor 1 (SUCNR1) is expressed in [beta] cells and is upregulated in hyperglycemic states in mice and humans. We found that succinate acted as a hormone-like metabolite and stimulated insulin secretion via a SUCNR1-Gq-PKC-dependent mechanism in human [beta] cells. Mice with [beta] cell-specific Sucnrl deficiency exhibited impaired glucose tolerance and insulin secretion on a high-fat diet, indicating that SUCNR1 is essential for preserving insulin secretion in diet-induced insulin resistance. Patients with impaired glucose tolerance showed an enhanced nutrition-related succinate response, which correlates with the potentiation of insulin secretion during intravenous glucose administration. These data demonstrate that the succinate/SUCNR1 axis is activated by high glucose and identify a GPCR- mediated amplifying pathway for insulin secretion relevant to the hyperinsulinemia of prediabetic states., Introduction Insulin secretion by pancreatic [beta] cells is crucial for blood glucose homeostasis and is tightly controlled by a complex network of hormones, nutrients, and neurotransmitters. Impaired [beta] cell function [...]

Aim: To evaluate the cross‐sectional association between severe periodontitis and diabetes mellitus (DM), in a representative sample of Spanish population. Materials and Methods: The di@bet.es epidemiological study is a population‐based cohort study aimed to determine the prevalence and incidence of DM in the adult population of Spain. The at‐risk sample at the final examination (2016–2017) included 1751 subjects who completed an oral health questionnaire. This questionnaire, together with demographic and risk factors, had been previously validated to build an algorithm to predict severe periodontitis in the Spanish population. Logistic regression models were used to evaluate the association between severe periodontitis and DM with adjustment for confounding factors. Results: In total, 144 subjects developed DM, which yielded 8.2% cumulative incidence. Severe periodontitis was detected in 59.0%, 54.7% or 68.8% of the subjects depending on three different selected criteria at the 2016–2017 exam. All criteria used to define severe periodontitis were associated with DM in unadjusted analysis, but the magnitude of the association decreased after adjusting for significant confounders. The criteria '≥50% of teeth with clinical attachment loss ≥5 mm' presented an odds ratio of 4.9 (95% confidence interval: 2.2–10.7; p ≤.001) for DM. Conclusions: Severe periodontitis is associated with DM in the Spanish population. [ABSTRACT FROM AUTHOR]

ObjectiveWe have previously shown that overexpression of the Na-Ca exchanger (NCX1), a protein responsible for Ca(2+) extrusion from cells, increases β-cell programmed cell death (apoptosis) and reduces β-cell proliferation. To further characterize the role of NCX1 in β-cells under in vivo conditions, we developed and characterized mice deficient for NCX1.Research design and methodsBiologic and morphologic methods (Ca(2+) imaging, Ca(2+) uptake, glucose metabolism, insulin release, and point counting morphometry) were used to assess β-cell function in vitro. Blood glucose and insulin levels were measured to assess glucose metabolism and insulin sensitivity in vivo. Islets were transplanted under the kidney capsule to assess their performance to revert diabetes in alloxan-diabetic mice.ResultsHeterozygous inactivation of Ncx1 in mice induced an increase in glucose-induced insulin release, with a major enhancement of its first and second phase. This was paralleled by an increase in β-cell proliferation and mass. The mutation also increased β-cell insulin content, proinsulin immunostaining, glucose-induced Ca(2+) uptake, and β-cell resistance to hypoxia. In addition, Ncx1(+/-) islets showed a two- to four-times higher rate of diabetes cure than Ncx1(+/+) islets when transplanted into diabetic animals.ConclusionsDownregulation of the Na/Ca exchanger leads to an increase in β-cell function, proliferation, mass, and resistance to physiologic stress, namely to various changes in β-cell function that are opposite to the major abnormalities seen in type 2 diabetes. This provides a unique model for the prevention and treatment of β-cell dysfunction in type 2 diabetes and after islet transplantation.

Tissue-specific transcriptional regulation is central to human disease. To identify regulatory DNA active in human pancreatic islets, we profiled chromatin by formaldehyde-assisted isolation of regulatory elements coupled with high-throughput sequencing (FAIRE-seq). We identified approximately 80,000 open chromatin sites. Comparison of FAIRE-seq data from islets to that from five non-islet cell lines revealed approximately 3,300 physically linked clusters of islet-selective open chromatin sites, which typically encompassed single genes that have islet-specific expression. We mapped sequence variants to open chromatin sites and found that rs7903146, a TCF7L2 intronic variant strongly associated with type 2 diabetes, is located in islet-selective open chromatin. We found that human islet samples heterozygous for rs7903146 showed allelic imbalance in islet FAIRE signals and that the variant alters enhancer activity, indicating that genetic variation at this locus acts in cis with local chromatin and regulatory changes. These findings illuminate the tissue-specific organization of cis-regulatory elements and show that FAIRE-seq can guide the identification of regulatory variants underlying disease susceptibility.

Aim: To assess how long participants with type 2 diabetes spent with HbA1c less than 7.0% and how likely they were to maintain this target with oral semaglutide 7 mg versus sitagliptin 100 mg or oral semaglutide 14 mg versus empagliflozin 25 mg, sitagliptin 100 mg or subcutaneous liraglutide 1.8 mg. Materials and Methods: Analyses used on‐treatment data without rescue medication for all randomized participants (semaglutide [approved maintenance doses], n = 1880; comparators [not including placebo], n = 1412). Duration of time with HbA1c less than 7.0% was calculated using an HbA1c time curve. A binary endpoint of achieving HbA1c less than 7.0% at weeks 26 (week 24 for PIONEER 7) and 52 of each trial (and week 78 for PIONEER 3) was analysed. Results: Mean duration of time with HbA1c less than 7.0% was greater with oral semaglutide 7 mg versus sitagliptin in PIONEER 3 (27 vs. 22 weeks) and with oral semaglutide 14 mg versus empagliflozin and sitagliptin (27‐34 vs. 19 vs. 22 weeks, respectively), and similar versus subcutaneous liraglutide. A greater proportion of participants achieved and maintained HbA1c less than 7.0% for more than 75% of the trial with oral semaglutide 14 mg versus oral comparators. The odds of achieving HbA1c less than 7.0% at weeks 24/26 and 52/78 were significantly greater with oral semaglutide 14 mg versus oral comparators or subcutaneous liraglutide, and with oral semaglutide 7 mg versus sitagliptin. Conclusions: Oral semaglutide 7 and 14 mg resulted in greater time spent with HbA1c less than 7.0%, and a greater likelihood of achieving and maintaining HbA1c less than 7.0% versus oral comparators. [ABSTRACT FROM AUTHOR]