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Diabetologia Oct 2023Incretin hormones (glucose-dependent insulinotropic polypeptide [GIP] and glucagon-like peptide-1 [GLP-1]) play a role in the pathophysiology of type 2 diabetes. Along... (Review)
Review
Incretin hormones (glucose-dependent insulinotropic polypeptide [GIP] and glucagon-like peptide-1 [GLP-1]) play a role in the pathophysiology of type 2 diabetes. Along with their derivatives they have shown therapeutic success in type 2 diabetes, with the potential for further improvements in glycaemic, cardiorenal and body weight-related outcomes. In type 2 diabetes, the incretin effect (greater insulin secretory response after oral glucose than with 'isoglycaemic' i.v. glucose, i.e. with an identical glycaemic stimulus) is markedly reduced or absent. This appears to be because of a reduced ability of GIP to stimulate insulin secretion, related either to an overall impairment of beta cell function or to specific defects in the GIP signalling pathway. It is likely that a reduced incretin effect impacts on postprandial glycaemic excursions and, thus, may play a role in the deterioration of glycaemic control. In contrast, the insulinotropic potency of GLP-1 appears to be much less impaired, such that exogenous GLP-1 can stimulate insulin secretion, suppress glucagon secretion and reduce plasma glucose concentrations in the fasting and postprandial states. This has led to the development of incretin-based glucose-lowering medications (selective GLP-1 receptor agonists or, more recently, co-agonists, e.g. that stimulate GIP and GLP-1 receptors). Tirzepatide (a GIP/GLP-1 receptor co-agonist), for example, reduces HbA and body weight in individuals with type 2 diabetes more effectively than selective GLP-1 receptor agonists (e.g. semaglutide). The mechanisms by which GIP receptor agonism may contribute to better glycaemic control and weight loss after long-term exposure to tirzepatide are a matter of active research and may change the pessimistic view that developed after the disappointing lack of insulinotropic activity in people with type 2 diabetes when exposed to GIP in short-term experiments. Future medications that stimulate incretin hormone and other receptors simultaneously may have the potential to further increase the ability to control plasma glucose concentrations and induce weight loss.
Topics: Humans; Incretins; Diabetes Mellitus, Type 2; Blood Glucose; Glucagon-Like Peptide-1 Receptor; Gastric Inhibitory Polypeptide; Glucagon-Like Peptide 1; Glucose; Body Weight; Weight Loss; Insulin
PubMed: 37430117
DOI: 10.1007/s00125-023-05956-x -
JAMA Nov 2023Tirzepatide is a glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist used for the treatment of type 2 diabetes. Efficacy and safety... (Comparative Study)
Comparative Study Randomized Controlled Trial
IMPORTANCE
Tirzepatide is a glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist used for the treatment of type 2 diabetes. Efficacy and safety of adding tirzepatide vs prandial insulin to treatment in patients with inadequate glycemic control with basal insulin have not been described.
OBJECTIVE
To assess the efficacy and safety of tirzepatide vs insulin lispro as an adjunctive therapy to insulin glargine.
DESIGN, SETTING, AND PARTICIPANTS
This open-label, phase 3b clinical trial was conducted at 135 sites in 15 countries (participants enrolled from October 19, 2020, to November 1, 2022) in 1428 adults with type 2 diabetes taking basal insulin.
INTERVENTIONS
Participants were randomized (in a 1:1:1:3 ratio) to receive once-weekly subcutaneous injections of tirzepatide (5 mg [n = 243], 10 mg [n = 238], or 15 mg [n = 236]) or prandial thrice-daily insulin lispro (n = 708).
MAIN OUTCOMES AND MEASURES
Outcomes included noninferiority of tirzepatide (pooled cohort) vs insulin lispro, both in addition to insulin glargine, in HbA1c change from baseline at week 52 (noninferiority margin, 0.3%). Key secondary end points included change in body weight and percentage of participants achieving hemoglobin A1c (HbA1c) target of less than 7.0%.
RESULTS
Among 1428 randomized participants (824 [57.7%] women; mean [SD] age, 58.8 [9.7] years; mean [SD] HbA1c, 8.8% [1.0%]), 1304 (91.3%) completed the trial. At week 52, estimated mean change from baseline in HbA1c with tirzepatide (pooled cohort) was -2.1% vs -1.1% with insulin lispro, resulting in mean HbA1c levels of 6.7% vs 7.7% (estimated treatment difference, -0.98% [95% CI, -1.17% to -0.79%]; P < .001); results met noninferiority criteria and statistical superiority was achieved. Estimated mean change from baseline in body weight was -9.0 kg with tirzepatide and 3.2 kg with insulin lispro (estimated treatment difference, -12.2 kg [95% CI, -13.4 to -10.9]). The percentage of participants reaching HbA1c less than 7.0% was 68% (483 of 716) with tirzepatide and 36% (256 of 708) with insulin lispro (odds ratio, 4.2 [95% CI, 3.2-5.5]). The most common adverse events with tirzepatide were mild to moderate gastrointestinal symptoms (nausea: 14%-26%; diarrhea: 11%-15%; vomiting: 5%-13%). Hypoglycemia event rates (blood glucose level <54 mg/dL or severe hypoglycemia) were 0.4 events per patient-year with tirzepatide (pooled) and 4.4 events per patient-year with insulin lispro.
CONCLUSIONS AND RELEVANCE
In people with inadequately controlled type 2 diabetes treated with basal insulin, weekly tirzepatide compared with prandial insulin as an additional treatment with insulin glargine demonstrated reductions in HbA1c and body weight with less hypoglycemia.
TRIAL REGISTRATION
ClinicalTrials.gov Identifier: NCT04537923.
Topics: Female; Humans; Male; Middle Aged; Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; Glycated Hemoglobin; Hypoglycemia; Hypoglycemic Agents; Insulin; Insulin Glargine; Insulin Lispro; Treatment Outcome; Internationality; Aged
PubMed: 37786396
DOI: 10.1001/jama.2023.20294 -
Peptides Jul 2023Within recent decades glucagon receptor (GcgR) agonism has drawn attention as a therapeutic tool for the treatment of type 2 diabetes and obesity. In both mice and... (Review)
Review
Within recent decades glucagon receptor (GcgR) agonism has drawn attention as a therapeutic tool for the treatment of type 2 diabetes and obesity. In both mice and humans, glucagon administration enhances energy expenditure and suppresses food intake suggesting a promising metabolic utility. Therefore synthetic optimization of glucagon-based pharmacology to further resolve the physiological and cellular underpinnings mediating these effects has advanced. Chemical modifications to the glucagon sequence have allowed for greater peptide solubility, stability, circulating half-life, and understanding of the structure-function potential behind partial and "super"-agonists. The knowledge gained from such modifications has provided a basis for the development of long-acting glucagon analogues, chimeric unimolecular dual- and tri-agonists, and novel strategies for nuclear hormone targeting into glucagon receptor-expressing tissues. In this review, we summarize the developments leading toward the current advanced state of glucagon-based pharmacology, while highlighting the associated biological and therapeutic effects in the context of diabetes and obesity.
Topics: Animals; Humans; Mice; Diabetes Mellitus, Type 2; Glucagon; Glucagon-Like Peptide 1; Obesity; Receptors, Glucagon
PubMed: 36997003
DOI: 10.1016/j.peptides.2023.171003 -
Diabetologia Oct 2023Glucagon-like peptide-1 (GLP-1) receptor agonists are established pharmaceutical therapies for the treatment of type 2 diabetes and obesity. They mimic the action of... (Review)
Review
Glucagon-like peptide-1 (GLP-1) receptor agonists are established pharmaceutical therapies for the treatment of type 2 diabetes and obesity. They mimic the action of GLP-1 to reduce glucose levels through stimulation of insulin secretion and inhibition of glucagon secretion. They also reduce body weight by inducing satiety through central actions. The GLP-1 receptor agonists used clinically are based on exendin-4 and native GLP-1 and are available as formulations for daily or weekly s.c. or oral administration. GLP-1 receptor agonism is also achieved by inhibitors of dipeptidyl peptidase-4 (DPP-4), which prevent the inactivation of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), thereby prolonging their raised levels after meal ingestion. Other developments in GLP-1 receptor agonism include the formation of small orally available agonists and compounds with the potential to pharmaceutically stimulate GLP-1 secretion from the gut. In addition, GLP-1/glucagon and GLP-1/GIP dual receptor agonists and GLP-1/GIP/glucagon triple receptor agonists have shown the potential to reduce blood glucose levels and body weight through their effects on islets and peripheral tissues, improving beta cell function and stimulating energy expenditure. This review summarises developments in gut hormone-based therapies and presents the future outlook for their use in type 2 diabetes and obesity.
Topics: Humans; Glucagon; Diabetes Mellitus, Type 2; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptide 1; Body Weight; Obesity; Glucose
PubMed: 37209227
DOI: 10.1007/s00125-023-05929-0 -
The Journal of Physiological Sciences :... Feb 2024Many hormones act on the hypothalamus to control hunger and satiety through various pathways closely associated with several factors. When food is present in the gastro... (Review)
Review
Many hormones act on the hypothalamus to control hunger and satiety through various pathways closely associated with several factors. When food is present in the gastro intestinal (GI) tract, enteroendocrine cells (EECs) emit satiety signals such as cholecystokinin (CCK), glucagon like peptide-1 (GLP-1) and peptide YY (PYY), which can then communicate with the vagus nerve to control food intake. More specifically, satiety has been shown to be particularly affected by the GLP-1 hormone and its receptor agonists that have lately been acknowledged as a promising way to reduce weight. In addition, there is increasing evidence that normal flora is also involved in the peripheral, central, and reward system that impact satiety. Moreover, neurologic pathways control satiety through neurotransmitters. In this review, we discuss the different roles of each of the GLP-1 hormone and its agonist, gut microbiomes, as well as neurotransmitters and their interconnected relation in the regulation of body's satiety homeostasis.
Topics: Cholecystokinin; Glucagon-Like Peptide 1; Peptide YY; Brain; Neurotransmitter Agents
PubMed: 38368346
DOI: 10.1186/s12576-024-00904-9 -
Hypertension (Dallas, Tex. : 1979) May 2024The renin-angiotensin system is the most important peptide hormone system in the regulation of cardiovascular homeostasis. Its classical arm consists of the enzymes,... (Review)
Review
The renin-angiotensin system is the most important peptide hormone system in the regulation of cardiovascular homeostasis. Its classical arm consists of the enzymes, renin, and angiotensin-converting enzyme, generating angiotensin II from angiotensinogen, which activates its AT receptor, thereby increasing blood pressure, retaining salt and water, and inducing cardiovascular hypertrophy and fibrosis. However, angiotensin II can also activate a second receptor, the AT receptor. Moreover, the removal of the C-terminal phenylalanine from angiotensin II by ACE2 (angiotensin-converting enzyme 2) yields angiotensin-(1-7), and this peptide interacts with its receptor Mas. When the aminoterminal Asp of angiotensin-(1-7) is decarboxylated, alamandine is generated, which activates the Mas-related G-protein-coupled receptor D, MrgD (Mas-related G-protein-coupled receptor type D). Since Mas, MrgD, and the AT receptor have opposing effects to the classical AT receptor, they and the enzymes and peptides activating them are called the alternative or protective arm of the renin-angiotensin system. This review will cover the historical aspects and the current standing of this recent addition to the biology of the renin-angiotensin system.
Topics: Angiotensin I; Angiotensin II; Peptide Fragments; Peptides; Peptidyl-Dipeptidase A; Receptors, G-Protein-Coupled; Renin; Renin-Angiotensin System; Humans
PubMed: 38362781
DOI: 10.1161/HYPERTENSIONAHA.123.21364 -
Cell Oct 2023Pollen-pistil interactions establish interspecific/intergeneric pre-zygotic hybridization barriers in plants. The rejection of undesired pollen at the stigma is crucial...
Pollen-pistil interactions establish interspecific/intergeneric pre-zygotic hybridization barriers in plants. The rejection of undesired pollen at the stigma is crucial to avoid outcrossing but can be overcome with the support of mentor pollen. The mechanisms underlying this hybridization barrier are largely unknown. Here, in Arabidopsis, we demonstrate that receptor-like kinases FERONIA/CURVY1/ANJEA/HERCULES RECEPTOR KINASE 1 and cell wall proteins LRX3/4/5 interact on papilla cell surfaces with autocrine stigmatic RALF1/22/23/33 peptide ligands (sRALFs) to establish a lock that blocks the penetration of undesired pollen tubes. Compatible pollen-derived RALF10/11/12/13/25/26/30 peptides (pRALFs) act as a key, outcompeting sRALFs and enabling pollen tube penetration. By treating Arabidopsis stigmas with synthetic pRALFs, we unlock the barrier, facilitating pollen tube penetration from distantly related Brassicaceae species and resulting in interspecific/intergeneric hybrid embryo formation. Therefore, we uncover a "lock-and-key" system governing the hybridization breadth of interspecific/intergeneric crosses in Brassicaceae. Manipulating this system holds promise for facilitating broad hybridization in crops.
Topics: Arabidopsis; Arabidopsis Proteins; Brassicaceae; Peptide Hormones; Peptides; Pollen; Pollen Tube; Reproductive Isolation
PubMed: 37806310
DOI: 10.1016/j.cell.2023.09.003 -
Frontiers in Endocrinology 2023
Topics: Humans; Adipokines; Leptin; Obesity; Neoplasms
PubMed: 38107522
DOI: 10.3389/fendo.2023.1340171