The dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist tirzepatide improves cardiovascular risk biomarkers in patients with type 2 diabetes: A post hoc analysis

In a phase 2 trial of once-weekly tirzepatide (1, 5, 10, or 15 mg), dulaglutide (1.5 mg), or placebo, the dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist tirzepatide dose-dependently reduced HbA1c and body weight in patients with type 2 diabetes. In this post hoc analysis, inflammation, endothelial dysfunction, and cellular stress biomarkers were measured at baseline, 4, 12, and 26 weeks to evaluate the additional effects of tirzepatide on cardiovascular risk factors. At 26 weeks, tirzepatide 10 and 15 mg decreased YKL-40 (also known as chitinase-3 like-protein-1), intercellular adhesion molecule 1 (ICAM-1), leptin, and growth differentiation factor 15 levels versus baseline, and YKL-40 and leptin levels versus placebo and dulaglutide. Tirzepatide 15 mg also decreased ICAM-1 levels versus placebo and dulaglutide, and high-sensitivity C-reactive protein (hsCRP) levels versus baseline and placebo, but not dulaglutide. GlycA, interleukin 6, vascular cell adhesion molecule 1, and N-terminal-pro hormone B-type natriuretic peptide levels were not significantly changed in any group. YKL-40, hsCRP, and ICAM-1 levels rapidly decreased within 4 weeks of treatment with tirzepatide 10 and 15 mg, whereas the decrease in leptin levels was more gradual and did not plateau by 26 weeks. In this hypothesis-generating exploratory analysis, tirzepatide decreased several biomarkers that have been associated with cardiovascular risk.     

The importance of glucose-dependent insulinotropic polypeptide receptor activation for the effects of tirzepatide

Tirzepatide is a unimolecular co-agonist of the glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors recently approved for the treatment of type 2 diabetes by the US Food and Drug Administration and the European Medicine Agency. Tirzepatide treatment results in an unprecedented improvement of glycaemic control and lowering of body weight, but the contribution of the GIP receptor-activating component of tirzepatide to these effects is uncertain. In this review, we present the current knowledge about the physiological roles of the incretin hormones GLP-1 and GIP, their receptors, and previous results of co-targeting the two incretin hormone receptors in humans. We also analyse the molecular pharmacological, preclinical and clinical effects of tirzepatide to discuss the role of GIP receptor activation for the clinical effects of tirzepatide. Based on the available literature on the combination of GLP-1 and GIP receptor activation, tirzepatide does not seem to have a classical co-activating mode of action in humans. Rather, in vitro studies of the human GLP-1 and GIP receptors reveal a biased GLP-1 receptor activation profile and GIP receptor downregulation. Therefore, we propose three hypotheses for the mode of action of tirzepatide, which can be addressed in future, elaborate clinical trials.     

Efficacy and safety of high-dose glucagon-like peptide-1, glucagon-like peptide-1/glucose-dependent insulinotropic peptide,and glucagon-like peptide-1/glucagon receptor agonists in type 2 diabetes

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have become agents of choice for people with type 2 diabetes (T2D) with established cardiovascular disease or in high-risk individuals. With currently available GLP-1 RAs, 51%-79% of subjects achieve an HbA1c target of less than 7.0% and 4%-27% lose 10% of body weight, illustrating the need for more potent agents. Three databases (PubMed, Cochrane, Web of Science) were searched using the MESH terms ‘glucagon-like peptide-1 receptor agonist’, ‘glucagon receptor agonist’, ‘glucose-dependent insulinotropic peptide’, ‘dual or co-agonist’, and ‘tirzepatide’. Quality of papers was scored using PRISMA guidelines. Risk of bias was evaluated using the Cochrane assessment tool. An HbA1c target of less than 7.0% was attained by up to 80% with high-dose GLP-1 RAs and up to 97% with tirzepatide, with even up to 62% of people with T2D reaching an HbA1c of less than 5.7%. A body weight loss of 10% or greater was obtained by up to 50% and up to 69% with high-dose GLP-1 RAs or tirzepatide, respectively. The glucose- and weight-lowering effects of the GLP-1/glucagon RA cotadutide equal those of liraglutide 1.8 mg. Gastrointestinal side effects of high-dose GLP-1 RAs and co-agonists occurred in 30%-70% of patients, mostly arising within the first 2 weeks of the first dose, being mild or moderate in severity, and transient. The development of high-dose GLP-1 RAs and the dual GLP-1/glucose-dependent insulinotropic peptide RA tirzepatide resulted in increasing numbers of people reaching HbA1c and body weight targets, with up to 62% attaining normoglycaemia with 15-mg tirzepatide. Whether this will also translate to better cardiovascular outcomes and affect treatment guidelines remains to be studied.     

Meta-analysis of head-to-head clinical trials comparing incretin-based glucose-lowering medications and basal insulin: An update including recently developed glucagon-like peptide-1 (GLP-1) receptor agonists and the glucose-dependent insulinotropic polypeptide/GLP-1 receptor co-agonist tirzepatide

Objective

To assess comparative efficacy, safety and tolerability of injectable incretin-based glucose-lowering medications (IBGLMs) versus basal insulin treatment in patients with type 2 diabetes.

Research Design and Methods

We performed an updated meta-analysis of randomized clinical trials of head-to-head comparisons of IBGLMs (short- and long-acting glucagon-like peptide-1 [GLP-1] receptor agonists [GLP-1RAs] and glucose-dependent insulinotropic polypeptide [GIP]/GLP-1 receptor co-agonist tirzepatide) versus basal insulin using a PubMed database search (April 2022). The primary endpoint was difference in reduction of glycated haemoglobin (HbA_1c) versus baseline between pooled IBGLMs (fixed-effects meta-analysis) and their subgroups (random-effects meta-analysis) versus basal insulin treatment (mean differences). Secondary endpoints were fasting plasma glucose, body weight, HbA_1c target achievement, hypoglycaemia, blood pressure and lipids. Risk of bias assessment was performed using Jadad scores and the Risk of Bias tool 2.0.

Results

In all, 20 studies, representing 47 study arms and 11 843 patients, were eligible. Compared with basal insulin, IGBLMs lowered HbA_1c by 0.48 (0.45-0.52)% more than did basal insulin treatment. This effect was driven by pooled long-acting GLP-1RAs (ΔHbA_1c −0.25 [−0.38; −0.11]%) and the only GIP/GLP-1 receptor co-agonist, tirzepatide (pooled doses; ΔHbA_1c −0.90 [−1.06; −0.75]%), while short-acting GLP-1RAs were equally effective compared with basal insulin (P = 0.90). All IBGLM subgroups achieved significantly lower body weight versus insulin treatment (−4.6 [−4.7; −4.4] kg), in particular tirzepatide (−12.0 [−13.8; −10.1] kg). IBGLMs significantly reduced hypoglycaemia and blood pressure and improved lipid variables. Risk of bias was low. IBGLM treatment was associated with more nausea, vomiting and diarrhoea and study medication discontinuation.

Conclusions

Recently introduced, highly effective IBGLMs were superior to basal insulin treatment, reinforcing the recommendation that IBGLMs should be considered as the first injectable treatment for most patients with type 2 diabetes.     

Achievement of glycaemic targets with weight loss and without hypoglycaemia in type 2 diabetes with the once-weekly glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonist tirzepatide: A post hoc analysis of the SURPASS-1 to -5 studies

Aim

To assess composite endpoints combining glycaemic control (HbA1c < 7.0%, ≤ 6.5% or < 5.7%) with weight loss (≥ 5%, ≥ 10% or ≥ 15%) and without hypoglycaemia with tirzepatide in type 2 diabetes (T2D).

Materials and Methods

Data from the phase 3 SURPASS programme were evaluated post hoc by trial. Participants with T2D were randomized to tirzepatide (5, 10 and 15 mg), placebo (SURPASS-1,5), semaglutide 1 mg (SURPASS-2) or titrated basal insulin (SURPASS-3,4). The proportions of participants achieving the composite endpoints were compared between tirzepatide and the respective comparator groups at week 40/52.

Results

The proportions of participants achieving an HbA1c value of less than 7.0% with 5% or more weight loss and without hypoglycaemia ranged from 43% to 82% with tirzepatide across the SURPASS-1 to -5 trials versus 4%-5% with placebo, 51% with semaglutide 1 mg and 5% with basal insulin (P < .001 vs. all comparators). The proportions of participants achieving an HbA1c value of less than 7.0% with 10% or more, or 15% or more weight loss and without hypoglycaemia were significantly higher with all tirzepatide doses versus comparators across trials (P < .001 or P < .05). Similar results were observed for all other combinations of endpoints with an HbA1c value of 6.5% or less, or less than 5.7%, with more tirzepatide-treated participants achieving these endpoints versus those in the comparator groups, including semaglutide.

Conclusions

Across the SURPASS-1 to -5 clinical trials, more tirzepatide-treated participants with T2D achieved clinically meaningful composite endpoints, which included reaching glycaemic targets with various degrees of weight loss and without hypoglycaemia, than those in the comparator groups.     

Fixed-ratio combination of basal insulin and glucagon-like peptide-1 receptor agonists in the treatment of Japanese people with type 2 diabetes: An innovative solution to a complex therapeutic challenge

Over 10 million people in Japan have known or suspected type 2 diabetes (T2D), and this number is expected to rise. Although many people require therapy escalation because of the progressive nature of T2D, this appears to be suboptimal in Japanese real-world clinical practice. Insulin therapy tends to be introduced only when glycaemic control is very poor (mean glycated haemoglobin >9%). Although basal insulin therapy is effective in reducing fasting plasma glucose (FPG), postprandial plasma glucose often remains uncontrolled. Basal-bolus insulin regimens are complex and carry the risk of weight gain and hypoglycaemia. Recently, fixed-ratio combinations (FRCs) of BI and glucagon-like peptide-1 receptor agonists (GLP-1RAs) have shown efficacy in reducing both FPG and postprandial plasma glucose with a single injection and without increased risk of hypoglycaemia or weight gain. IDegLira, a titratable FRC of insulin degludec (100 U/mL) and liraglutide, is currently available in Japan and the United States/European Union at a ratio of 1 U (unit):0.036 mg. iGlarLixi (insulin glargine 100 U/mL and lixisenatide at a ratio of 1:1 (20 U/20 μg) has recently been approved in Japan. Phase 3 trials in Japan for IDegLira (DUAL Japan) and iGlarLixi (LixiLan JP) have shown that both FRCs are efficacious. This review provides an overview of IDegLira and iGlarLixi (Japanese formulation) and considers their potential use as new therapeutic options to address the clinical need for early glycaemic control in Japanese people with T2D.     

Preventing all-cause hospitalizations in type 2 diabetes with sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1 receptor agonists: A narrative review and proposed clinical approach

Patients with type 2 diabetes (T2D) are at increased risk for hospital admissions, and acute hospitalizations are associated with a worse prognosis. However, outcomes related to all-cause hospital admissions (ACHAs) were often overlooked in trials that demonstrated the cardiovascular and kidney benefits of sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RAs). This review includes a contemporary literature summary of emerging data regarding the effects of SGLT2 inhibitors and GLP-1RAs on ACHAs. The role of SGLT2 inhibitors in preventing ACHAs was shown in exploratory investigations of several randomized controlled trials (RCTs) and was further supported by real-world evidence (RWE). However, the association between GLP-1RA use and lower ACHA risk was mainly shown through RWE, with minimal available RCT data. We also discuss the advantages and challenges of studying ACHAs. Finally, we propose an easily memorized (“ABCDE” acronym) clinical approach to evaluating T2D status and treatment in admitted patients, as they transition from hospital to community care. This systematic approach may assist clinicians in recognizing possible pitfalls in T2D management, thereby preventing subsequent hospitalizations and improving patient prognoses. While acute admission can sometimes be perceived as a management failure, it should also be viewed as an opportunity to take action to prevent the next hospitalization.     

The evolving story of incretins (GIP and GLP-1) in metabolic and cardiovascular disease: A pathophysiological update

The incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) have their main physiological role in augmenting insulin secretion after their nutrient-induced secretion from the gut. A functioning entero-insular (gut-endocrine pancreas) axis is essential for the maintenance of a normal glucose tolerance. This is exemplified by the incretin effect (greater insulin secretory response to oral as compared to “isoglycaemic” intravenous glucose administration due to the secretion and action of incretin hormones). GIP and GLP-1 have additive effects on insulin secretion. Local production of GIP and/or GLP-1 in islet α-cells (instead of enteroendocrine K and L cells) has been observed, and its significance is still unclear. GLP-1 suppresses, and GIP increases glucagon secretion, both in a glucose-dependent manner. GIP plays a greater physiological role as an incretin. In type 2-diabetic patients, the incretin effect is reduced despite more or less normal secretion of GIP and GLP-1. While insulinotropic effects of GLP-1 are only slightly impaired in type 2 diabetes, GIP has lost much of its acute insulinotropic activity in type 2 diabetes, for largely unknown reasons. Besides their role in glucose homoeostasis, the incretin hormones GIP and GLP-1 have additional biological functions: GLP-1 at pharmacological concentrations reduces appetite, food intake, and—in the long run—body weight, and a similar role is evolving for GIP, at least in animal studies. Human studies, however, do not confirm these findings. GIP, but not GLP-1 increases triglyceride storage in white adipose tissue not only through stimulating insulin secretion, but also by interacting with regional blood vessels and GIP receptors. GIP, and to a lesser degree GLP-1, play a role in bone remodelling. GLP-1, but not GIP slows gastric emptying, which reduces post-meal glycaemic increments. For both GIP and GLP-1, beneficial effects on cardiovascular complications and neurodegenerative central nervous system (CNS) disorders have been observed, pointing to therapeutic potential over and above improving diabetes complications. The recent finding that GIP/GLP-1 receptor co-agonists like tirzepatide have superior efficacy compared to selective GLP-1 receptor agonists with respect to glycaemic control as well as body weight has renewed interest in GIP, which previously was thought to be without any therapeutic potential. One focus of this research is into the long-term interaction of GIP and GLP-1 receptor signalling. A GLP-1 receptor antagonist (exendin [9-39]) and, more recently, a GIP receptor agonist (GIP [3-30] NH₂) and, hopefully, longer-acting GIP receptor agonists for human use will be helpful tools to shed light on the open questions. A detailed knowledge of incretin physiology and pathophysiology will be a prerequisite for designing more effective incretin-based diabetes drugs.     

Clinical characteristics,treatment patterns,and persistence in individuals with type 2 diabetes initiating a glucagon-like peptide-1 receptor agonist: A retrospective analysis of the Diabetes Prospective Follow-Up Registry

Aims

To describe clinical characteristics, treatment patterns and glucagon-like peptide-1 receptor agonist (GLP-1 RA) persistence in individuals with type 2 diabetes (T2D) initiating their first GLP-1 RA.

Materials and Methods

A real-world analysis of adults with T2D initiating GLP-1 RA therapy between 2007 and June 2020 from the multicentre Diabetes Prospective Follow-Up (DPV) Registry, stratified by antidiabetes therapy at the time of GLP-1 RA initiation: oral antidiabetic drugs (OAD), insulin ± OAD or lifestyle modification (LM). GLP-1 RA treatment persistence in individuals with ≥12 months follow-up was determined by Kaplan-Meier analysis.

Results

Overall, 15 111 individuals with T2D initiating GLP-1 RA therapy (55% men) were identified; median [interquartile range (IQR)] age [58.7 (50.6-66.7) years], diabetes duration [8.5 (3.6-14.7) years], glycated haemoglobin [HbA1c; 8.2 (7.1-9.8)%]. Median (95% confidence interval) GLP-1 RA persistence in eligible individuals (n = 5189) was 11 (10-12) months; OAD 12 (11-14) months (n = 2453); insulin ± OAD 11 (9-12) months (n = 2204); and LM 7 (5-9) months (n = 532). Median treatment persistence tended to increase from 2007-2012 to 2017-2020. Median (IQR) HbA1c decreased from baseline [8.2 (7.1-9.8)%] to discontinuation [7.5 (6.6-8.7)%], with a greater decrease observed in individuals with persistence >12 months versus ≤12 months. Individuals who discontinued GLP-1 RA therapy predominantly switched to insulin (if not already using) or dipeptidyl peptidase-4 inhibitors.

Conclusion

Real-world registry data revealed improved outcomes with longer median GLP-1 RA persistence; ~50% of patients overall achieved HbA1c <7% at 12 months. Persistence was highest with baseline OAD and/or insulin, and tended to increase over the period 2007-2020.     

Cardiovascular effects of sodium-glucose co-transporter-2 inhibitors and glucagon-like peptide-1 receptor agonists: The P value and beyond

Despite growing awareness of the dangers of a dichotomous interpretation of trial results based on the ‘statistical significance’ of a treatment effect, the uptake of new approaches has been slow in diabetes medicine. We showcase a number of ways to interpret the evidence for a treatment effect applied to the cardiovascular outcome trials of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium-glucose co-transporter-2 inhibitors (SGLT-2is): the P value function (or confidence curves), which depicts the treatment effect across the whole spectrum of confidence levels; the counternull value, which is the hazard ratio (i.e. treatment effect size) supported by the same amount of evidence as the null value (i.e. no treatment effect); and the S value, which quantifies the strength of the evidence against the null hypothesis in terms of the number of coin tosses yielding the same side. We show how this approach identifies potential treatment effects, highlights similarities among trials straddling the threshold of statistical significance, and quantifies differences in the strength of the evidence from trials reporting statistically significant results. For example, while REWIND, CANVAS and CREDENCE failed to reach statistical significance at the .05 level for all-cause mortality, their counternull values indicate that reduced death rates by 19%, 24% and 31%, respectively, are supported by the same amount of evidence as that indicating no treatment effect. Moreover, similarities among results emerge in trials of GLP-1RAs (REWIND, EXSCEL and LEADER) lying closely around the threshold of ‘statistical significance’. Lastly, several S values, such as for the primary outcome in HARMONY Outcomes (S value 10.9) and all-cause death in EMPAREG-OUTCOME (S value 15.0), stand out compared with values for other outcomes and other trials, suggesting much larger differences in the evidence between these studies and several others that cluster around the .05 significance threshold. P value functions, counternull values and S values should complement the standard reporting of the treatment effect to help interpret clinical trials and make decisions among competing glucose-lowering medications.