Potent incretin-based therapy for obesity: A systematic review and meta-analysis of the efficacy of semaglutide and tirzepatide on body weight and waist circumference, and safety.

Potent incretin-based therapy shows promise for the treatment of obesity along with reduced incidence of cardiovascular events in patients with preexisting cardiovascular disease and obesity. This study assessed the efficacy and safety of the incretin-based obesity treatments, once-weekly subcutaneous semaglutide 2.4 mg and tirzepatide 10 or 15 mg, in people with obesity without diabetes. Of the 744 records identified, seven randomized controlled trials (n = 5140) were included. Five studies (n = 3288) investigated semaglutide and two studies (n = 1852) investigated tirzepatide. The treatment effect, shown as placebo-subtracted difference, on body weight was -15.0% (95% CI, -17.8 to -12.2) with -12.9% (95% CI, -14.7 to -11.1) for semaglutide and -19.2% (95% CI, -22.2 to -16.2) for tirzepatide. The treatment effect on waist circumference was -11.4 cm (95% CI, -13.7 to -9.2) with -9.7 cm (95% CI, -10.8 to -8.5) for semaglutide and -14.6 cm (95% CI, -15.8 to -13.4) for tirzepatide. The adverse events related to semaglutide and tirzepatide were primarily of mild-to-moderate severity and mostly gastrointestinal, which was more frequent during the dose-titration period and leveled off during the treatment period. This emphasizes that once-weekly subcutaneous semaglutide 2.4 mg and tirzepatide 10 or 15 mg induce large reductions in body weight and waist circumference and are generally well-tolerated.

Neprilysin activity is increased in metabolic dysfunction-associated steatotic liver disease and normalizes after bariatric surgery or GLP-1 therapy.

Inhibitors of neprilysin improve glycemia in patients with heart failure and type 2 diabetes (T2D). The effect of weight loss by diet, surgery, or pharmacotherapy on neprilysin activity (NEPa) is unknown. We investigated circulating NEPa and neprilysin protein concentrations in obesity, T2D, metabolic dysfunction-associated steatotic liver disease (MASLD), and following bariatric surgery, or GLP-1-receptor-agonist therapy. NEPa, but not neprilysin protein, was enhanced in obesity, T2D, and MASLD. Notably, MASLD associated with NEPa independently of BMI and HbA1c. NEPa decreased after bariatric surgery with a concurrent increase in OGTT-stimulated GLP-1. Diet-induced weight loss did not affect NEPa, but individuals randomized to 52-week weight maintenance with liraglutide (1.2 mg/day) decreased NEPa, consistent with another study following 6-week liraglutide (3 mg/day). A 90-min GLP-1 infusion did not alter NEPa. Thus, MASLD may drive exaggerated NEPa, and lowered NEPa following bariatric surgery or liraglutide therapy may contribute to the reported improved cardiometabolic effects.

Increased meal-induced neurotensin response predicts successful maintenance of weight loss - Data from a randomized controlled trial.

BACKGROUND: The gut derived anorexigenic hormone neurotensin (NT) is upregulated after bariatric surgery which may contribute to the sustained weight loss. In contrast, diet-induced weight loss is most often followed by weight regain. We therefore investigated whether diet-induced weight loss impacts levels of circulating NT in mice and humans and whether NT levels predicts body weight change after weight loss in humans. METHODS: In vivo mice study: Obese mice were fed ad-libitum or a restricted diet (40-60 % of average food intake) for 9 days to obtain similar weight loss as observed in the human study. At termination, intestinal segments, the hypothalamus and plasma were collected for histological, real time PCR, and radioimmunoassay (RIA) analysis. CLINICAL TRIAL: Plasma samples from 42 participants with obesity, completing an 8-week low-calorie diet in a randomized controlled trial, were analyzed. Plasma NT was measured by RIA at fasting and during a meal test before and after diet-induced weight loss and after one year of intended weight maintenance. RESULTS: In obese mice, food restriction-induced body weight loss of 14 % was associated with a 64 % reduction in fasting plasma NT (p < 0.0001). In the mouse duodenum (p = 0.07) and jejunum (p < 0.05), NT tissue concentration was decreased without tissue atrophy indicative of a physiological downregulation. In the mouse hypothalamus a downregulation of Pomc (p < 0.01) along with upregulation of Npy (p < 0.001) and Agrp (p < 0.0001) expression was found after restricted feeding in support of increased hunger after diet-induced weight loss. Therefore, we investigated the NT response in humans undergoing weight loss maintenance. In humans, similar to the mice, the low-calorie diet induced weight loss of 13 % body weight was associated with 40 % reduction in fasting plasma NT levels (p < 0.001). Meal-induced NT peak responses were greater in humans who lost additional weight during the 1 year maintenance phase compared to participants who regained weight (p < 0.05). CONCLUSION: Diet-induced weight loss decreased fasting plasma NT levels in both humans and mice with obesity, and regulated hunger-associated hypothalamic gene expression in mice. Meal-induced NT responses were greater in humans who lost additional weight during the 1 year maintenance phase compared to participants who regained weight. This indicates that increased peak secretion of NT after weight loss may contribute to successful maintenance of weight loss. CLINICAL TRIAL REGISTRATION NUMBER: NCT02094183.

Exploratory analysis of eating- and physical activity-related outcomes from a randomized controlled trial for weight loss maintenance with exercise and liraglutide single or combination treatment.

Weight regain after weight loss remains a major challenge in obesity treatment and may involve alteration of eating and sedentary behavior after weight loss. In this randomized, controlled, double-blind trial, adults with obesity were randomized, in a 1:1:1:1 ratio stratified by sex and age group (<40 years and ≥40 years), to one-year weight loss maintenance with exercise, the GLP-1 receptor agonist liraglutide, or the combination, as compared with placebo, after low-calorie diet-induced weight loss. Primary outcome was change in body weight, which has been published. Here, we investigated the effects of weight loss maintenance with exercise, liraglutide, or the combination on weight loss-induced changes in the pre-specified explorative outcomes, eating and sedentary behavior in 130 participants who completed the trial according to the study protocol (exercise (n = 26), liraglutide (n = 36), combination (n = 29), and placebo (n = 39)). One year after weight loss, the placebo group had decreased postprandial appetite suppression score by 14%, and increased sedentary time by 31 min/day and regained weight. Liraglutide prevented the decrease in postprandial appetite suppression score compared with placebo (0% vs. -14%; P = 0.023) and maintained weight loss. Exercise after weight loss did not increase appetite or sedentary behavior compared with placebo, despite increased exercise energy expenditure and maintained weight loss. The combination of exercise and liraglutide increased cognitive restraint score (13% vs. -9%; P = 0.042), reflecting a conscious restriction of food intake, and decreased sedentary time by 41 min/day (-10 vs. 31 min/day; 95%CI, -82.3 to -0.2; P = 0.049) compared with placebo, which may have facilitated the additional weight loss. Targeting both eating and sedentary behavior could be the most effective for preventing weight regain.Trial registration: EudraCT number, 2015-005585-32; clinicaltrials.gov number, NCT04122716.

Fat-Secreted Ceramides Regulate Vascular Redox State and Influence Outcomes in Patients With Cardiovascular Disease.

BACKGROUND: Obesity is associated with increased cardiovascular risk; however, the potential role of dysregulations in the adipose tissue (AT) metabolome is unknown. OBJECTIVES: The aim of this study was to explore the role of dysregulation in the AT metabolome on vascular redox signaling and cardiovascular outcomes. METHODS: A screen was conducted for metabolites differentially secreted by thoracic AT (ThAT) and subcutaneous AT in obese patients with atherosclerosis (n = 48), and these metabolites were then linked with dysregulated vascular redox signaling in 633 patients undergoing coronary bypass surgery. The underlying mechanisms were explored in human aortic endothelial cells, and their clinical value was tested against hard clinical endpoints. RESULTS: Because ThAT volume was associated significantly with arterial oxidative stress, there were significant differences in sphingolipid secretion between ThAT and subcutaneous AT, with C16:0-ceramide and derivatives being the most abundant species released within adipocyte-derived extracellular vesicles. High ThAT sphingolipid secretion was significantly associated with reduced endothelial nitric oxide bioavailability and increased superoxide generated in human vessels. Circulating C16:0-ceramide correlated positively with ThAT ceramides, dysregulated vascular redox signaling, and increased systemic inflammation in 633 patients with atherosclerosis. Exogenous C16:0-ceramide directly increased superoxide via tetrahydrobiopterin-mediated endothelial nitric oxide synthase uncoupling and dysregulated protein phosphatase 2 in human aortic endothelial cells. High plasma C16:0-ceramide and its glycosylated derivative were independently related with increased risk for cardiac mortality (adjusted hazard ratios: 1.394; 95% confidence interval: 1.030 to 1.886; p = 0.031 for C16:0-ceramide and 1.595; 95% confidence interval: 1.042 to 2.442; p = 0.032 for C16:0-glycosylceramide per 1 SD). In a randomized controlled clinical trial, 1-year treatment of obese patients with the glucagon-like peptide-1 analog liraglutide suppressed plasma C16:0-ceramide and C16:0-glycosylceramide changes compared with control subjects. CONCLUSIONS: These results demonstrate for the first time in humans that AT-derived ceramides are modifiable regulators of vascular redox state in obesity, with a direct impact on cardiac mortality in advanced atherosclerosis. (The Interaction Between Appetite Hormones; NCT02094183).

Glucose-Dependent Insulinotropic Peptide in the High-Normal Range Is Associated With Increased Carotid Intima-Media Thickness.

OBJECTIVE: While existing evidence supports beneficial cardiovascular effects of glucagon-like peptide 1 (GLP-1), emerging studies suggest that glucose-dependent insulinotropic peptide (GIP) and/or signaling via the GIP receptor may have untoward cardiovascular effects. Indeed, recent studies show that fasting physiological GIP levels are associated with total mortality and cardiovascular mortality, and it was suggested that GIP plays a role in pathogenesis of coronary artery disease. We investigated the associations between fasting and postchallenge GIP and GLP-1 concentrations and subclinical atherosclerosis as measured by mean intima-media thickness in the common carotid artery (IMTmeanCCA) and maximal intima-media thickness in the carotid bifurcation (IMTmaxBulb). RESEARCH DESIGN AND METHODS: Participants at reexamination within the Malmö Diet and Cancer-Cardiovascular Cohort study (n = 3,734, mean age 72.5 years, 59.3% women, 10.8% subjects with diabetes, fasting GIP available for 3,342 subjects, fasting GLP-1 available for 3,299 subjects) underwent oral glucose tolerance testing and carotid ultrasound. RESULTS: In linear regression analyses, each 1-SD increment of fasting GIP was associated with increased (per mm) IMTmeanCCA (ß = 0.010, P = 0.010) and IMTmaxBulb (ß = 0.014; P = 0.040) in models adjusted for known risk factors and glucose metabolism. In contrast, each 1-SD increment of fasting GLP-1 was associated with decreased IMTmaxBulb (per mm, ß = -0.016, P = 0.014). These associations remained significant when subjects with diabetes were excluded from analyses. CONCLUSIONS: In a Swedish elderly population, physiologically elevated levels of fasting GIP are associated with increased IMTmeanCCA, while GLP-1 is associated with decreased IMTmaxBulb, further emphasizing diverging cardiovascular effects of these two incretin hormones.

Glucagon acutely regulates hepatic amino acid catabolism and the effect may be disturbed by steatosis.

OBJECTIVE: Glucagon is well known to regulate blood glucose but may be equally important for amino acid metabolism. Plasma levels of amino acids are regulated by glucagon-dependent mechanism(s), while amino acids stimulate glucagon secretion from alpha cells, completing the recently described liver-alpha cell axis. The mechanisms underlying the cycle and the possible impact of hepatic steatosis are unclear. METHODS: We assessed amino acid clearance in vivo in mice treated with a glucagon receptor antagonist (GRA), transgenic mice with 95% reduction in alpha cells, and mice with hepatic steatosis. In addition, we evaluated urea formation in primary hepatocytes from ob/ob mice and humans, and we studied acute metabolic effects of glucagon in perfused rat livers. We also performed RNA sequencing on livers from glucagon receptor knock-out mice and mice with hepatic steatosis. Finally, we measured individual plasma amino acids and glucagon in healthy controls and in two independent cohorts of patients with biopsy-verified non-alcoholic fatty liver disease (NAFLD). RESULTS: Amino acid clearance was reduced in mice treated with GRA and mice lacking endogenous glucagon (loss of alpha cells) concomitantly with reduced production of urea. Glucagon administration markedly changed the secretion of rat liver metabolites and within minutes increased urea formation in mice, in perfused rat liver, and in primary human hepatocytes. Transcriptomic analyses revealed that three genes responsible for amino acid catabolism (Cps1, Slc7a2, and Slc38a2) were downregulated both in mice with hepatic steatosis and in mice with deletion of the glucagon receptor. Cultured ob/ob hepatocytes produced less urea upon stimulation with mixed amino acids, and amino acid clearance was lower in mice with hepatic steatosis. Glucagon-induced ureagenesis was impaired in perfused rat livers with hepatic steatosis. Patients with NAFLD had hyperglucagonemia and increased levels of glucagonotropic amino acids, including alanine in particular. Both glucagon and alanine levels were reduced after diet-induced reduction in Homeostatic Model Assessment for Insulin Resistance (HOMA-IR, a marker of hepatic steatosis). CONCLUSIONS: Glucagon regulates amino acid metabolism both non-transcriptionally and transcriptionally. Hepatic steatosis may impair glucagon-dependent enhancement of amino acid catabolism.

Role of fasting duration and weekday in incretin and glucose regulation.

Fasting duration has been associated with lower fasting blood glucose levels, but higher 2-h post-load levels, and research has indicated an adverse effect of 'weekend behavior' on human metabolism. We investigated associations of fasting duration and weekday of examination with glucose, insulin, glucagon and incretin responses to an oral glucose tolerance test (OGTT). This cross-sectional study is based on data from the ADDITION-PRO study, where 2082 individuals attended a health examination including an OGTT. Linear regression analysis was applied to study the associations of overnight fasting duration and day of the week with glucose, insulin, glucagon, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) responses to an OGTT. We found that a 1 h longer fasting duration was associated with 1.7% (95% CI: 0.8,2.5) higher 2-h glucose levels, as well as a 3.0% (95% CI: 1.3,4.7) higher GIP and 2.3% (95% CI: 0.3,4.4) higher GLP-1 response. Fasting insulin levels were 20.6% (95% CI: 11.2,30.7) higher on Mondays compared to the other weekdays, with similar fasting glucose levels (1.7%, 95% CI: 0.0,3.4). In this study, longer overnight fasting duration was associated with a worsening of glucose tolerance and increased incretin response to oral glucose. We found higher fasting insulin levels on Mondays compared to the other days of the week, potentially indicating a worsened glucose regulation after the weekend.

Glucose-dependent insulinotropic peptide and risk of cardiovascular events and mortality: a prospective study.

AIMS/HYPOTHESIS: Evidence that glucose-dependent insulinotropic peptide (GIP) and/or the GIP receptor (GIPR) are involved in cardiovascular biology is emerging. We hypothesised that GIP has untoward effects on cardiovascular biology, in contrast to glucagon-like peptide 1 (GLP-1), and therefore investigated the effects of GIP and GLP-1 concentrations on cardiovascular disease (CVD) and mortality risk. METHODS: GIP concentrations were successfully measured during OGTTs in two independent populations (Malmö Diet Cancer-Cardiovascular Cohort [MDC-CC] and Prevalence, Prediction and Prevention of Diabetes in Botnia [PPP-Botnia]) in a total of 8044 subjects. GLP-1 (n = 3625) was measured in MDC-CC. The incidence of CVD and mortality was assessed via national/regional registers or questionnaires. Further, a two-sample Mendelian randomisation (2SMR) analysis between the GIP pathway and outcomes (coronary artery disease [CAD] and myocardial infarction) was carried out using a GIP-associated genetic variant, rs1800437, as instrumental variable. An additional reverse 2SMR was performed with CAD as exposure variable and GIP as outcome variable, with the instrumental variables constructed from 114 known genetic risk variants for CAD. RESULTS: In meta-analyses, higher fasting levels of GIP were associated with risk of higher total mortality (HR[95% CI] = 1.22 [1.11, 1.35]; p = 4.5 × 10-5) and death from CVD (HR[95% CI] 1.30 [1.11, 1.52]; p = 0.001). In accordance, 2SMR analysis revealed that increasing GIP concentrations were associated with CAD and myocardial infarction, and an additional reverse 2SMR revealed no significant effect of CAD on GIP levels, thus confirming a possible effect solely of GIP on CAD. CONCLUSIONS/INTERPRETATION: In two prospective, community-based studies, elevated levels of GIP were associated with greater risk of all-cause and cardiovascular mortality within 5-9 years of follow-up, whereas GLP-1 levels were not associated with excess risk. Further studies are warranted to determine the cardiovascular effects of GIP per se.

[The glucagon-like peptide-1 receptor-agonist semaglutide].

Semaglutide is a glucagon-like peptide-1 receptor-agonist (GLP-1 RA), which is injected subcutaneously once a week for treatment of Type 2 diabetes. In this review, the present results of semaglutide treatment are presented. Semaglutide has been evaluated in more than 8,000 patients across the spectrum of Type 2 diabetes. Trials with semaglutide have demonstrated superiority with sustained improved glycaemic control and weight loss compared to oral antidiabetic agents, other GLP-1 RAs and basalinsulin. In addition, semaglutide significantly decreased the occurrence of cardiovascular events compared with standard pharmacological diabetic treatment combined with placebo.

Benefit-Risk Assessment of Obesity Drugs: Focus on Glucagon-like Peptide-1 Receptor Agonists.

The prevalence of obesity and related comorbidities is increasing worldwide. Furthermore, clinically meaningful body weight losses has proven difficult to achieve and especially to maintain through sustained lifestyle change in the form of diet and exercise. Pharmacotherapy against obesity is a non-invasive treatment as an adjunct to lifestyle changes, but approved anti-obesity drugs are currently few. This article reviews the major anti-obesity drugs and the benefit-risk profiles of the long-acting glucagon-like peptide-1 receptor agonists (GLP-1 RAs) liraglutide and semaglutide (a modified version of liraglutide with longer half-life and tripled receptor affinity). Generally, GLP-1 RAs are well tolerated and induce significant weight loss and lowering of comorbidities. Studies with liraglutide 3.0 mg/day have shown an average placebo-subtracted weight loss of 5.5 kg (range 4.6-5.9) in 1- to 3-year duration trials. One trial using semaglutide 0.4 mg once daily reported an average weight loss of 11.6% (~ 13.1 kg) after 1 year. Furthermore, semaglutide induced a ~ 6 percentage point larger placebo-subtracted body weight loss in a head-to-head comparison with liraglutide (11.6 vs. 5.5% weight loss, respectively). The safety profiles for both drugs were similar, with transient gastrointestinal disorders being the most commonly reported adverse events. The longest running trial and the most recent trials have not raised any new safety concerns. Long-term trials and post-marketing surveillance is warranted to fully assess both long-term efficacy and safety. Future combinational therapies of mimicked gut hormones involved in regulation of energy homeostasis and/or additional lifestyle change in the form of exercise might further improve efficacy.

Plasma Proteome Profiling Reveals Dynamics of Inflammatory and Lipid Homeostasis Markers after Roux-En-Y Gastric Bypass Surgery.

Obesity-related diseases affect half of the global population, and bariatric surgery is one of the few interventions with long-lasting weight loss and cardio-metabolic effects. Here, we investigated the effect of Roux-en-Y gastric bypass surgery on the plasma proteome, hypothesizing that specific proteins or protein patterns may serve as key mediators and markers of the metabolic response. We performed mass spectrometry (MS)-based proteomics on two longitudinal studies encompassing 47 morbidly obese patients, generating quantitative information on more than 1,700 proteins. A global correlation matrix incorporating about 200,000 relationships revealed functional connections between proteins and assigned them to physiological processes. The main classes of significantly altered proteins were markers of systemic inflammation and those involved in lipid metabolism. Our data highlight robust correlative and anti-correlative behaviors of circulating proteins to each other and to clinical parameters. A group of inflammation-related proteins showed distinct inverse relationships to proteins consistently associated with insulin sensitivity.

Common variants in the hERG (KCNH2) voltage-gated potassium channel are associated with altered fasting and glucose-stimulated plasma incretin and glucagon responses.

BACKGROUND: Patients with long QT syndrome due to rare loss-of-function mutations in the human ether-á-go-go-related gene (hERG) have prolonged QT interval, risk of arrhythmias, increased secretion of insulin and incretins and impaired glucagon response to hypoglycemia. This is caused by a dysfunctional Kv11.1 voltage-gated potassium channel. Based on these findings in patients with rare variants in hERG, we hypothesized that common variants in hERG may also lead to alterations in glucose homeostasis. Subsequently, we aimed to evaluate the effect of two common gain-of-function variants in hERG (rs36210421 and rs1805123) on QT interval and plasma levels of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), insulin and glucagon during an oral glucose tolerance test (OGTT). We used two population-based cohorts for evaluation of the effect of common variants in hERG on QT-interval and circulation levels of incretins, insulin and glucagon. The Danish population-based Inter99 cohort (n = 5895) was used to assess the effect of common variants on QT-interval. The Danish ADDITION-PRO cohort was used (n = 1329) to study genetic associations with levels of GLP-1, GIP, insulin and glucagon during an OGTT. RESULTS: Carriers of either the minor A-allele of rs36210421 or the minor G-allele of rs1805123 had ~ 2 ms shorter QT interval per risk allele (p = 0.025 and p = 1.9 × 10- 7). Additionally, both variants were associated with alterations in pancreatic and gut hormone release among carriers. The minor A- allele of rs36210421 was associated with increased GLP-1 and decreased GIP response to oral glucose stimulation, whereas the minor G-allele of rs1805123 is associated with decreased fasting plasma insulin and glucagon release. A genetic risk score combining the two gene variants revealed reductions in glucose-stimulated GIP, as well as suppressed glucagon response to increased glucose levels during an OGTT. CONCLUSIONS: Two common missense polymorphisms of the Kv11.1 voltage-gated hERG potassium channel are associated with alterations in circulating levels of GIP and glucagon, suggesting that hERG potassium channels play a role in fasting and glucose-stimulated release of GIP and glucagon. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT00289237 ). Trial retrospectively registered at February 9, 2006. Studies were approved by the Ethical Committee of the Central Denmark Region (journal no. 20080229) and by the Copenhagen County Ethical Committee (KA 98155).

Glucose ingestion causes cardiac repolarization disturbances in type 1 long QT syndrome patients and healthy subjects.

BACKGROUND: Both hypoglycemia and severe hyperglycemia constitute known risk factors for cardiac repolarization changes potentially leading to malignant arrhythmias. Patients with loss of function mutations in KCNQ1 are characterized by long QT syndrome (LQTS) and may be at increased risk for glucose-induced repolarization disturbances. OBJECTIVE: The purpose of this study was to test the hypothesis that KCNQ1 LQTS patients are at particular risk for cardiac repolarization changes during the relative hyperglycemia that occurs after an oral glucose load. METHODS: Fourteen KCNQ1 LQTS patients and 28 control participants matched for gender, body mass index, and age underwent a 3-hour oral 75-g glucose tolerance test with ECGs obtained at 7 time points. Fridericia corrected QT interval (QTcF), Bazett corrected QT interval (QTcB), and the Morphology Combination Score (MCS) were calculated. RESULTS: QTc and MCS increased in both groups. MCS remained elevated until 150 minutes after glucose ingestion, and the maximal change from baseline was larger among KCNQ1 LQTS patients compared with control subjects (0.28 ± 0.27 vs 0.15 ± 0.13; P <.05). CONCLUSION: Relative hyperglycemia induced by ingestion of 75-g glucose caused cardiac repolarization disturbances that were more severe in KCNQ1 LQTS patients compared with control subjects.

Patients With Long-QT Syndrome Caused by Impaired hERG-Encoded Kv11.1 Potassium Channel Have Exaggerated Endocrine Pancreatic and Incretin Function Associated With Reactive Hypoglycemia.

BACKGROUND: Loss-of-function mutations in hERG (encoding the Kv11.1 voltage-gated potassium channel) cause long-QT syndrome type 2 (LQT2) because of prolonged cardiac repolarization. However, Kv11.1 is also present in pancreatic α and ß cells and intestinal L and K cells, secreting glucagon, insulin, and the incretins glucagon-like peptide-1 (GLP-1) and GIP (glucose-dependent insulinotropic polypeptide), respectively. These hormones are crucial for glucose regulation, and long-QT syndrome may cause disturbed glucose regulation. We measured secretion of these hormones and cardiac repolarization in response to glucose ingestion in LQT2 patients with functional mutations in hERG and matched healthy participants, testing the hypothesis that LQT2 patients have increased incretin and ß-cell function and decreased α-cell function, and thus lower glucose levels. METHODS: Eleven patients with LQT2 and 22 sex-, age-, and body mass index-matched control participants underwent a 6-hour 75-g oral glucose tolerance test with ECG recording and blood sampling for measurements of glucose, insulin, C-peptide, glucagon, GLP-1, and GIP. RESULTS: In comparison with matched control participants, LQT2 patients had 56% to 78% increased serum insulin, serum C-peptide, plasma GLP-1, and plasma GIP responses (P=0.03-0.001) and decreased plasma glucose levels after glucose ingestion (P=0.02) with more symptoms of hypoglycemia (P=0.04). Sixty-three percent of LQT2 patients developed hypoglycemic plasma glucose levels (<70 mg/dL) versus 36% control participants (P=0.16), and 18% patients developed serious hypoglycemia (<50 mg/dL) versus none of the controls. LQT2 patients had defective glucagon responses to low glucose, P=0.008. ß-Cell function (Insulin Secretion Sensitivity Index-2) was 2-fold higher in LQT2 patients than in controls (4398 [95% confidence interval, 2259-8562] versus 2156 [1961-3201], P=0.03). Pharmacological Kv11.1 blockade (dofetilide) in rats had similar effect, and small interfering RNA inhibition of hERG in ß and L cells increased insulin and GLP-1 secretion up to 50%. Glucose ingestion caused cardiac repolarization disturbances with increased QTc intervals in both patients and controls, but with a 122% greater increase in QTcF interval in LQT2 patients (P=0.004). CONCLUSIONS: Besides a prolonged cardiac repolarization phase, LQT2 patients display increased GLP-1, GIP, and insulin secretion and defective glucagon secretion, causing decreased plasma glucose and thus increased risk of hypoglycemia. Furthermore, glucose ingestion increased QT interval and aggravated the cardiac repolarization disturbances in LQT2 patients. CLINICAL TRIAL REGISTRATION: URL: http://clinicaltrials.gov. Unique identifier: NCT02775513.

Searching for the physiological role of glucose-dependent insulinotropic polypeptide.

Glucose-dependent insulinotropic polypeptide (GIP) was established as a gut hormone more than 40 years ago, and there is good experimental support for its role as an incretin hormone although deletion of the GIP receptor or the GIP cells or GIP receptor mutations have only minor effects on glucose metabolism. Unlike the related hormone, GLP-1, GIP stimulates the secretion of glucagon, which in healthy individuals may help to stabilize glucose levels, but in people with type 2 diabetes may contribute to glucose intolerance. A role in lipid metabolism is supported by numerous indirect observations and by resistance to diet-induced obesity after deletion of the GIP receptor. However, a clear effect on lipid clearance could not be identified in humans, raising doubt about its importance. The GIP receptor is widely expressed in the body and also appears to be expressed on bone cells, and experimental studies in rodent point to effects on bone metabolism. Recent studies revealed pronounced inhibitory effects of GIP on bone resorption markers in humans and suggest that GIP may be (one of the) gastrointestinal regulators of bone turn-over. In support of this, a loss-of-function GIP receptor mutation in humans is associated with a marked increase in fracture risk. The lack of a reliable GIP receptor antagonist contributes to the uncertainty regarding the physiological role of GIP.

Successful weight loss maintenance includes long-term increased meal responses of GLP-1 and PYY3-36.

OBJECTIVE: The hormones glucagon-like peptide 1 (GLP-1), peptide YY3-36 (PYY3-36), ghrelin, glucose-dependent insulinotropic polypeptide (GIP) and glucagon have all been implicated in the pathogenesis of obesity. However, it is unknown whether they exhibit adaptive changes with respect to postprandial secretion to a sustained weight loss. DESIGN: The study was designed as a longitudinal prospective intervention study with data obtained at baseline, after 8 weeks of weight loss and 1 year after weight loss. METHODS: Twenty healthy obese individuals obtained a 13% weight loss by adhering to an 8-week very low-calorie diet (800kcal/day). After weight loss, participants entered a 52-week weight maintenance protocol. Plasma levels of GLP-1, PYY3-36, ghrelin, GIP and glucagon during a 600-kcal meal were measured before weight loss, after weight loss and after 1 year of weight maintenance. Area under the curve (AUC) was calculated as total AUC (tAUC) and incremental AUC (iAUC). RESULTS: Weight loss was successfully maintained for 52 weeks. iAUC for GLP-1 increased by 44% after weight loss (P<0.04) and increased to 72% at week 52 (P=0.0001). iAUC for PYY3-36 increased by 74% after weight loss (P<0.0001) and by 36% at week 52 (P=0.02). tAUC for ghrelin increased by 23% after weight loss (P<0.0001), but at week 52, the increase was reduced to 16% compared with before weight loss (P=0.005). iAUC for GIP increased by 36% after weight loss (P=0.001), but returned to before weight loss levels at week 52. Glucagon levels were unaffected by weight loss. CONCLUSIONS: Meal responses of GLP-1 and PYY3-36 remained increased 1 year after weight maintenance, whereas ghrelin and GIP reverted toward before-weight loss values. Thus, an increase in appetite inhibitory mechanisms and a partly decrease in appetite-stimulating mechanisms appear to contribute to successful long-term weight loss maintenance.

Glucose-Dependent Insulinotropic Polypeptide Is Associated With Lower Low-Density Lipoprotein But Unhealthy Fat Distribution, Independent of Insulin: The ADDITION-PRO Study.

CONTEXT: Glucose-dependent insulinotropic polypeptide (GIP) may increase lipid clearance by stimulating lipid uptake. However, given that GIP promotes release of insulin by the pancreas and insulin is anti-lipolytic, the effect may be indirect. OBJECTIVE: In this study we examined the association between GIP and lipid metabolism in individuals with low to high risk of type 2 diabetes and assessed whether the associations were modified by or mediated through insulin. DESIGN, SETTING, AND PARTICIPANTS: Analyses were based on the Danish cross-sectional ADDITION-PRO study (n = 1405). Lipid metabolism was measured by fasting plasma lipids and obesity including abdominal fat distribution assessed by ultrasonography. GIP and insulin were measured during an oral glucose tolerance test (0, 30 and 120 min). Linear regression analysis was used to study the associations between GIP, plasma lipids, and obesity measures. RESULTS: A doubling in fasting GIP levels was associated with lower low-density lipoprotein in both men (mean [95% CI] -0.10 mmol/l [-0.18--0.03]) and women (-0.14 mmol/l [-0.23--0.04]) and with higher high-density lipoprotein in women (0.06 mmol/l [-0.02-0.10]). In men, a doubling in stimulated GIP was associated with 0.13 cm less 0.01-0.25 sc fat but with more visceral abdominal fat (0.45 cm [0.12-0.78]) and higher waist-hip ratio (0.011 [0.004-0.019]). CONCLUSIONS: Contrary to what was previously thought, GIP may be associated with improved low-density lipoprotein clearance but with an unhealthy fat distribution independent of insulin. The effect of GIP on obesity measures was substantially different between men and women. The potential effect of GIP on visceral and sc adipose tissue physiology warrants further examination.

Therapies for inter-relating diabetes and obesity - GLP-1 and obesity.

INTRODUCTION: The dramatic rise in the prevalence of obesity and type 2 diabetes mellitus (T2DM) is associated with increased mortality, morbidity as well as public health care expenses worldwide. The need for effective and long-lasting pharmaceutical treatment is obvious. The record of anti-obesity drugs has been poor so far and the only efficient treatment today is bariatric surgery. Research has indicated that appetite inhibiting hormones from the gut may have a therapeutic potential in obesity. The gut incretin hormone, glucagon-like peptide-1 (GLP-1), appears to be involved in both peripheral and central pathways mediating satiety. Clinical trials have shown that two GLP-1 receptor agonists exenatide and liraglutide have a weight-lowering potential in non-diabetic obese individuals. Furthermore, they may also hold a potential in preventing diabetes as compared to other weight loss agents. AREAS COVERED: The purpose of this review is to cover the background for the GLP-1-based therapies and their potential in obesity and pre-diabetes. Up-to-date literature on incretin-based therapies will be summarized with a special mention of their weight-lowering properties. The literature updated to August 2014 from PubMed was identified using the combinations: GLP-1, GLP-1 receptor agonists, incretins, obesity and pre-diabetes. EXPERT OPINION: The incretin impairment, which seems to exist in both obesity and diabetes, may link these two pathologies and underlines the potential of GLP-1-based therapies in the prevention and treatment of these diseases.