Insights from the Liraglutide Clinical Development Program--the Liraglutide Effect and Action in Diabetes (LEAD) studies

Glucagon-like peptide agonists: A prospective review

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as promising therapeutic options for addressing Type-2 diabetes, obesity, and related conditions. Among these, semaglutide, tirzepatide, liraglutide etc., all notable GLP-1RA, have gained attention owing to their favourable pharmacological properties and clinical efficacy.

AIMS

This comprehensive review aims to provide a detailed analysis of both the currently available GLP-1RAs in the market and those undergoing clinical trials. The focus is on examining their mechanism of action, pharmacokinetics, efficacy in glycemic control and weight management, safety profile, and potential applications.

MATERIALS & METHODS

The review employs a systematic approach to gather information on GLP-1RAs. Relevant literature from the currently literature and ongoing clinical trials is thoroughly examined. Detailed scrutiny is applied to understand the mechanism of action, pharmacokinetic properties, and clinical outcomes of these agents.

RESULTS

The review presents a comprehensive overview of the GLP-1RAs, highlighting their distinct mechanisms of action, pharmacokinetic profiles, and clinical effectiveness in glycemic control and weight management. Safety profiles are also discussed, providing a holistic understanding of these therapeutic agents.

DISCUSSION

The findings are discussed in the context of advancements in the field of GLP-1RAs. Potential applications beyond diabetes and obesity are explored, shedding light on the broader implications of these agents in managing related conditions.

CONCLUSION

In conclusion, this review underscores the significance of GLP-1RAs, with a specific focus on semaglutide, in the management of type 2 diabetes, obesity, and beyond. By synthesizing information on their mechanisms, pharmacokinetics, efficacy, and safety, this review provides valuable insights into the potential benefits these agents offer, contributing to the ongoing discourse in the field.

Liraglutide Effect on Weight, Glycated Hemoglobin, and Blood Pressure: A Single-Center Experience in the Eastern Province of Saudi Arabia

Background

Liraglutide has pleiotropic effects beneficial to patients with cardiovascular and renal risks. These effects have been linked to weight and blood pressure reduction in type 2 diabetes (T2D) patients. However, whether this reduction is similar in all patients regardless of their ethnicity, baseline demographic, or clinical characteristics is unknown. This study aimed to identify the efficacy of liraglutide on weight, glycated hemoglobin (HbA1c), and blood pressure in Saudi patients with T2D who attended King Fahad Hospital of the University and received liraglutide as add-on therapy to other antihyperglycemic agents. The study also aimed to describe the pattern of change in these clinical parameters before and after the treatment and assess whether sex differences affect liraglutide's efficacy.

Methods

We conducted a retrospective longitudinal study reviewing medical records of 220 Saudi patients with T2D treated at King Fahad Hospital of the University (KFHU), in Al-Khobar city in the Eastern Province of Saudi Arabia, from December 2016 to November 2021. Patient cases were included if the patient was Saudi, aged 18 or older, and received liraglutide in a dose of at least 0.6 mg/day for at least three months in combination with other antihyperglycemic agents/diabetes medications. We recorded the effect on patient HbA1c, systolic blood pressure (SBP) and diastolic blood pressure (DBP), body mass index (BMI), and body weight at baseline, during, and after treatment. We used the paired t-test and repeated measure analysis of variance to compare the mean study parameters before and after treatment. Furthermore, an independent t-test was used to compare the mean study parameters among men and women.

Results

Treatment with liraglutide from 0.6 mg/day to 3 mg/day for three to 18 months had optimal results across the outcomes measured in our cohort study. There was a significant reduction in weight from baseline to 18 months from a mean weight of 97.9±20 kg to 96.51±18.45 kg with (p<0.001). Mean HbA1c at baseline was 9.34%±1.95%, dropped to 7.67%±1.11% (p<0.001) at 18 months. Moreover, mean SBP also significantly decreased from 126.61±10.4 mmHg to 122.48±7.29 mmHg by the last follow-up (p<0.001). Mean DBP was 76.54±8.37 mmHg at baseline and decreased to 74.29±6.22 mmHg at last follow-up (p<0.001). Men treated with liraglutide had greater reductions in weight than women throughout the study (p<0.05), and while men had greater reductions in SBP and DBP than women early in treatment (p<0.05), by the end of treatment, there were no significant differences in blood pressure between men and women. Likewise, we saw no significant difference between HbA1c reductions in men and women treated with liraglutide.

Conclusion

Liraglutide effectively reduces HbA1c, weight, BMI, SBP, and DBP in T2D patients. These study results reflect real-world liraglutide clinical practices from KFHU and can be beneficial for physicians when considering using liraglutide as add-on therapy in this population.

GLP-1 Analogs and DPP-4 Inhibitors in Type 2 Diabetes Therapy: Review of Head-to-Head Clinical Trials

The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are released from enteroendocrine cells in response to the presence of nutrients in the small intestines. These homones facilitate glucose regulation by stimulating insulin secretion in a glucose dependent manner while suppressing glucagon secretion. In patients with type 2 diabetes (T2DM), an impaired insulin response to GLP-1 and GIP contributes to hyperglycemia. Dipeptidyl peptidase-4 (DPP-4) inhibitors block the breakdown of GLP-1 and GIP to increase levels of the active hormones. In clinical trials, DPP-4 inhibitors have a modest impact on glycemic control. They are generally well-tolerated, weight neutral and do not increase the risk of hypoglycemia. GLP-1 receptor agonists (GLP-1 RA) are peptide derivatives of either exendin-4 or human GLP-1 designed to resist the activity of DPP-4 and therefore, have a prolonged half-life. In clinical trials, they have demonstrated superior efficacy to many oral antihyperglycemic drugs, improved weight loss and a low risk of hypoglycemia. However, GI adverse events, particularly nausea, vomiting, and diarrhea are seen. Both DPP-4 inhibitors and GLP-1 RAs have demonstrated safety in robust cardiovascular outcome trials, while several GLP-1 RAs have been shown to significantly reduce the risk of major adverse cardiovascular events in persons with T2DM with pre-existing cardiovascular disease (CVD). Several clinical trials have directly compared the efficacy and safety of DPP-4 inhibitors and GLP-1 RAs. These studies have generally demonstrated that the GLP-1 RA provided superior glycemic control and weight loss relative to the DPP-4 inhibitor. Both treatments were associated with a low and comparable incidence of hypoglycemia, but treatment with GLP-1 RAs were invariably associated with a higher incidence of GI adverse events. A few studies have evaluated switching patients from DPP-4 inhibitors to a GLP-1RA and, as expected, improved glycemic control and weight loss are seen following the switch. According to current clinical guidelines, GLP-1RA and DPP-4 inhibitors are both indicated for the glycemic management of patients with T2DM across the spectrum of disease. GLP-1RA may be preferred over DPP- 4 inhibitors for many patients because of the greater reductions in hemoglobin A1c and weight loss observed in the clinical trials. Among patients with preexisting CVD, GLP-1 receptor agonists with a proven cardiovascular benefit are indicated as add-on to metformin therapy.

Incidence and severity of hypoglycaemia in type 2 diabetes by treatment regimen: A UK multisite 12-month prospective observational study

AIMS

To determine the incidence and severity of self-reported hypoglycaemia in a primary care population with type 2 diabetes. The study also aimed to compare incidence by treatment regimen.

MATERIALS AND METHODS

A prospective observational study in 17 centres throughout the UK was conducted. Recruitment was based on treatment regimen (metformin alone, sulphonylurea-, insulin- or incretin-based therapy). Participants were asked to keep a blood glucose diary and self-report hypoglycaemia episodes [non-severe (self-treated) and severe (requiring external help)] over a 12-month period.

RESULTS

Three hundred and twenty-five participants were enrolled, of whom 274 (84%) returned ≥1 monthly diaries. Overall, 39% reported experiencing hypoglycaemia; 32% recorded ≥1 symptomatic, 36% ≥1 non-severe, and 7% ≥1 severe episodes. By treatment, incidence (events per person/year) for any hypoglycaemia type was 4.39 for insulin, 2.34 for sulphonylurea, 0.76 for metformin, and 0.56 for incretin-based therapy. Compared with metformin, risk of non-severe hypoglycaemia was ~3 times higher for participants on sulphonylureas and > 5 times higher for those on insulin [incidence rate ratio (IRR) 3.02 (1.76-5.18), P < 0.001, and IRR 5.96 (3.48-10.2), P < 0.001, respectively]. For severe episodes, the incidence for sulphonylurea (0.09) was similar to metformin (0.07) and incretin-based therapy (0.07); for insulin the risk remained almost 5 times higher than metformin [incidence 0.32; IRR 4.55 (1.28-16.20), P = 0.019].

CONCLUSIONS

Hypoglycaemia represents a substantial burden for people with type 2 diabetes. Sulphonylureas and insulin are both associated with a risk of reported non-severe hypoglycaemia, but only insulin with severe episodes. This suggests the importance of the continued use of sulphonylureas in appropriate patients with type 2 diabetes.

Metformin and second- or third-generation sulphonylurea combination therapy for adults with type 2 diabetes mellitus

BACKGROUND

The number of people with type 2 diabetes mellitus (T2DM) is increasing worldwide. The combination of metformin and sulphonylurea (M+S) is a widely used treatment. Whether M+S shows better or worse effects in comparison with other antidiabetic medications for people with T2DM is still controversial.

OBJECTIVES

To assess the effects of metformin and sulphonylurea (second- or third-generation) combination therapy for adults with type 2 diabetes mellitus.

SEARCH METHODS

We updated the search of a recent systematic review from the Agency for Healthcare Research and Quality (AHRQ). The updated search included CENTRAL, MEDLINE, Embase, ClinicalTrials.gov and WHO ICTRP. The date of the last search was March 2018. We searched manufacturers' websites and reference lists of included trials, systematic reviews, meta-analyses and health technology assessment reports. We asked investigators of the included trials for information about additional trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) randomising participants 18 years old or more with T2DM to M+S compared with metformin plus another glucose-lowering intervention or metformin monotherapy with a treatment duration of 52 weeks or more.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles and records, assessed risk of bias and extracted outcome data independently. We used a random-effects model to perform meta-analysis, and calculated risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the certainty of the evidence using the GRADE instrument.

MAIN RESULTS

We included 32 RCTs randomising 28,746 people. Treatment duration ranged between one to four years. We judged none of these trials as low risk of bias for all 'Risk of bias' domains. Most important events per person were all-cause and cardiovascular mortality, serious adverse events (SAE), non-fatal stroke (NFS), non-fatal myocardial infarction (MI) and microvascular complications. Most important comparisons were as follows:Five trials compared M+S (N = 1194) with metformin plus a glucagon-like peptide 1 analogue (N = 1675): all-cause mortality was 11/1057 (1%) versus 11/1537 (0.7%), risk ratio (RR) 1.15 (95% confidence interval (CI) 0.49 to 2.67); 3 trials; 2594 participants; low-certainty evidence; cardiovascular mortality 1/307 (0.3%) versus 1/302 (0.3%), low-certainty evidence; serious adverse events (SAE) 128/1057 (12.1%) versus 194/1537 (12.6%), RR 0.90 (95% CI 0.73 to 1.11); 3 trials; 2594 participants; very low-certainty evidence; non-fatal myocardial infarction (MI) 2/549 (0.4%) versus 6/1026 (0.6%), RR 0.57 (95% CI 0.12 to 2.82); 2 trials; 1575 participants; very low-certainty evidence.Nine trials compared M+S (N = 5414) with metformin plus a dipeptidyl-peptidase 4 inhibitor (N = 6346): all-cause mortality was 33/5387 (0.6%) versus 26/6307 (0.4%), RR 1.32 (95% CI 0.76 to 2.28); 9 trials; 11,694 participants; low-certainty evidence; cardiovascular mortality 11/2989 (0.4%) versus 9/3885 (0.2%), RR 1.54 (95% CI 0.63 to 3.79); 6 trials; 6874 participants; low-certainty evidence; SAE 735/5387 (13.6%) versus 779/6307 (12.4%), RR 1.07 (95% CI 0.97 to 1.18); 9 trials; 11,694 participants; very low-certainty evidence; NFS 14/2098 (0.7%) versus 8/2995 (0.3%), RR 2.21 (95% CI 0.74 to 6.58); 4 trials; 5093 participants; very low-certainty evidence; non-fatal MI 15/2989 (0.5%) versus 13/3885 (0.3%), RR 1.45 (95% CI 0.69 to 3.07); 6 trials; 6874 participants; very low-certainty evidence; one trial in 64 participants reported no microvascular complications were observed (very low-certainty evidence).Eleven trials compared M+S (N = 3626) with metformin plus a thiazolidinedione (N = 3685): all-cause mortality was 123/3300 (3.7%) versus 114/3354 (3.4%), RR 1.09 (95% CI 0.85 to 1.40); 6 trials; 6654 participants; low-certainty evidence; cardiovascular mortality 37/2946 (1.3%) versus 41/2994 (1.4%), RR 0.78 (95% CI 0.36 to 1.67); 4 trials; 5940 participants; low-certainty evidence; SAE 666/3300 (20.2%) versus 671/3354 (20%), RR 1.01 (95% CI 0.93 to 1.11); 6 trials; 6654 participants; very low-certainty evidence; NFS 20/1540 (1.3%) versus 16/1583 (1%), RR 1.29 (95% CI 0.67 to 2.47); P = 0.45; 2 trials; 3123 participants; very low-certainty evidence; non-fatal MI 25/1841 (1.4%) versus 21/1877 (1.1%), RR 1.21 (95% CI 0.68 to 2.14); P = 0.51; 3 trials; 3718 participants; very low-certainty evidence; three trials (3123 participants) reported no microvascular complications (very low-certainty evidence).Three trials compared M+S (N = 462) with metformin plus a glinide (N = 476): one person died in each intervention group (3 trials; 874 participants; low-certainty evidence); no cardiovascular mortality (2 trials; 446 participants; low-certainty evidence); SAE 34/424 (8%) versus 27/450 (6%), RR 1.68 (95% CI 0.54 to 5.21); P = 0.37; 3 trials; 874 participants; low-certainty evidence; no NFS (1 trial; 233 participants; very low-certainty evidence); non-fatal MI 2/215 (0.9%) participants in the M+S group; 2 trials; 446 participants; low-certainty evidence; no microvascular complications (1 trial; 233 participants; low-certainty evidence).Four trials compared M+S (N = 2109) with metformin plus a sodium-glucose co-transporter 2 inhibitor (N = 3032): all-cause mortality was 13/2107 (0.6%) versus 19/3027 (0.6%), RR 0.96 (95% CI 0.44 to 2.09); 4 trials; 5134 participants; very low-certainty evidence; cardiovascular mortality 4/1327 (0.3%) versus 6/2262 (0.3%), RR 1.22 (95% CI 0.33 to 4.41); 3 trials; 3589 participants; very low-certainty evidence; SAE 315/2107 (15.5%) versus 375/3027 (12.4%), RR 1.02 (95% CI 0.76 to 1.37); 4 trials; 5134 participants; very low-certainty evidence; NFS 3/919 (0.3%) versus 7/1856 (0.4%), RR 0.87 (95% CI 0.22 to 3.34); 2 trials; 2775 participants; very low-certainty evidence; non-fatal MI 7/890 (0.8%) versus 8/1374 (0.6%), RR 1.43 (95% CI 0.49 to 4.18; 2 trials); 2264 participants; very low-certainty evidence; amputation of lower extremity 1/437 (0.2%) versus 1/888 (0.1%); very low-certainty evidence.Trials reported more hypoglycaemic episodes with M+S combination compared to all other metformin-antidiabetic agent combinations. Results for M+S versus metformin monotherapy were inconclusive. There were no RCTs comparing M+S with metformin plus insulin. We identified nine ongoing trials and two trials are awaiting assessment. Together these trials will include approximately 16,631 participants.

AUTHORS' CONCLUSIONS

There is inconclusive evidence whether M+S combination therapy compared with metformin plus another glucose-lowering intervention results in benefit or harm for most patient-important outcomes (mortality, SAEs, macrovascular and microvascular complications) with the exception of hypoglycaemia (more harm for M+S combination). No RCT reported on health-related quality of life.

Peptide-based multi-agonists: a new paradigm in metabolic pharmacology

Obesity and its comorbidities, such as type 2 diabetes, are pressing worldwide health concerns. Available anti-obesity treatments include weight loss pharmacotherapies and bariatric surgery. Whilst surgical interventions typically result in significant and sustained weight loss, available pharmacotherapies are far less effective, typically decreasing body weight by no more than 5-10%. An emerging class of multi-agonist drugs may eventually bridge this gap. This new class of specially tailored drugs hybridizes the amino acid sequences of key metabolic hormones into one single entity with enhanced potency and sustained action. Successful examples of this strategy include multi-agonist drugs targeting the receptors for glucagon-like peptide-1 (GLP-1), glucagon and the glucose-dependent insulinotropic polypeptide (GIP). Due to the simultaneous activity at several metabolically relevant receptors, these multi-agonists offer improved body weight loss and glucose tolerance relative to their constituent monotherapies. Further advancing this concept, chimeras were generated that covalently link nuclear acting hormones such as oestrogen, thyroid hormone (T₃ ) or dexamethasone to peptide hormones such as GLP-1 or glucagon. The benefit of this strategy is to restrict the nuclear hormone action exclusively to cells expressing the peptide hormone receptor, thereby maximizing combinatorial metabolic efficacy of both drug constituents in the target cells whilst preventing the nuclear hormone cargo from entering and acting on cells devoid of the peptide hormone receptor, in which the nuclear hormone might have unwanted effects. Many of these multi-agonists are in preclinical and clinical development and may represent new and effective tools in the fight against obesity and its comorbidities.

The efficacy and safety of liraglutide added to metformin in patients with diabetes: a meta-analysis of randomized controlled trials

Liraglutide, a glucagon-like peptide (GLP-1) receptor agonist, has showed favorable effects in the glycaemic control and weight reduction in patients with type 2 diabetes mellitus (T2DM). The meta-analysis was to compare the efficacy and safety of liraglutide added to metformin with other treatments in patients with T2DM. A systematic literature search on PubMed, Embase, Web of Science and the Cochrane library databases were performed. Eligible studies were randomized controlled trials (RCTs) of patients with T2DM who received the combination treatment of liraglutide and metformin. Pooled estimates were performed using a fixed-effects model or random-effects model. A total of nine RCTs met the inclusion criteria. Compared with control (placebo, sitagliptin, glimepiride, dulaglutide, insulin glargine, and NPH), liraglutide in combination with metformin resulted in significant reductions in HbA1c, bodyweight, FPG, and PPG, and similar reductions in SBP, and DBP. Moreover, liraglutide combined with metformin did not increase the risk of hypoglycemia, but induced a higher incidence of gastrointestinal disorders. In conclusion, this meta-analysis confirmed the use of liraglutide as add-on to metformin appeared to be effective and safe for patients with T2DM. However, considering the potential limitations in this study, more large-scale, well-conducted RCTs are needed to identify our findings.

GLP-1 and Amylin in the Treatment of Obesity

For decades, extensive research has aimed to clarify the role of pancreas and gut-derived peptide hormones in the regulation of glucose homeostasis and feeding behavior. Among these are the beta-cell hormone amylin and the intestinal L cell hormone glucagon-like peptide-1 (GLP-1). They exhibit distinct and yet several similar physiological actions including suppression of food intake, postprandial glucagon secretion, and gastric emptying-altogether lowering plasma glucose and body weight. These actions have been clinically exploited by the development of amylin and GLP-1 hormone analogs now used for treatment of diabetes and obesity. This review will outline the physiology and pharmacological potential of amylin and GLP-1, respectively, and focus on innovative peptide drug development leading to drugs acting on two or more distinct receptors, such as an amylin and GLP-1 peptide hybrid, potentially producing a more effective treatment strategy to combat the rapidly increasing global obesity.

Investigation of Morphological and Functional Changes in the Small Intestine With Pancreatic Disease

OBJECTIVES

The aim of this study was to investigate the relationship between pancreas and small intestine evaluating the endoscopic and histopathologic findings of the proximal small intestine in pancreatic diseases.

METHODS

Fifty patients (18 patients with chronic pancreatitis, 17 patients with pancreatic cancer, 15 control subjects) underwent enteroscopy using a prototype enteroscope. The villous height of the jejunum on bioptic specimens was measured, and the mean values of the villi were compared among the 3 groups. Exocrine function was calculated by the pancreatic function diagnostic test, and the correlation between the recovery rate of p-aminobenzoic acid and the villous height was assessed. Finally, the distribution of the K cells secreting glucose-dependent insulinotropic polypeptide and the L cells secreting glucagon-like peptide 1 in the duodenum and jejunum was investigated using immunohistochemistry for glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1.

RESULTS

The mean villous height in chronic pancreatitis (328 ± 67 μm) was significantly lower than that in pancreatic cancer (413 ± 57 μm) and control subjects (461 ± 97 μm) (P = 0.004 and P < 0.0001, respectively). A positive correlation was found between the recovery rate of p-aminobenzoic acid and the villous height (r = 0.52, P = 0.0001). The presence of K and L cells was verified in the duodenum and the jejunum.

CONCLUSIONS

Close relationship between pancreas and small intestine was demonstrated.

An Overview of Current Regulatory Requirements for Approval of Biosimilar Insulins

Insulin analog patent expiry is likely to mean that, increasingly, copies of original biopharmaceutical products will be submitted for authorization. Experience with biosimilars in other therapeutic areas suggests that careful regulation and caution are needed. Published guidelines of regulatory authorities around the world on approval of biosimilars and, where available, insulin biosimilars were reviewed. Information was sourced through Internet searching and cross-referencing guidelines. As of August 2014, general biosimilar and insulin-specific guidelines are available in 34 countries and two countries/regulatory domains, respectively. Many guidelines are clearly related to, or partly derived from, the general and insulin-specific European Medicines Agency (EMA) guidelines. Areas covered by these guidelines are fairly consistent, covering preclinical, pharmacokinetic (PK), and pharmacodynamic (PD) studies in humans and clinical areas; however, there are differences in emphasis. The EMA insulin-specific guidelines include detailed criteria on PK/PD studies, as do most other general biosimilar guidelines and, to a lesser extent, clinical studies. The U.S. Food and Drug Administration has general biosimilar guidelines, emphasizing consideration of the whole package of in vitro, biological, and human studies, rather than concentrating on any one aspect. In countries such as Mexico, guidelines are broad, leaving wide discretion to the regulatory authority. In conclusion, from a global perspective, this area of drug regulation is heterogeneous and evolving, and the authors call for an initiative aimed at harmonizing the requirements for biosimilar insulins.

GLP-1 receptor agonists: effects on cardiovascular risk reduction

Comorbid obesity, dyslipidemia, and hypertension place patients with type 2 diabetes (T2DM) at greatly increased risk of cardiovascular (CV) disease-related morbidity and mortality. An urgent need exists for effective treatment for patients with T2DM that encompasses glycemic control, weight loss, and reduction in CV risk factors. The glucagon-like peptide-1 receptor agonists (GLP-1 RAs) liraglutide and exenatide are incretin-based antidiabetes agents. This review examines CV-associated effects of liraglutide and exenatide in animal models and clinical trials with patients with T2DM. Studies support the effectiveness of GLP-1 RAs in reducing hyperglycemia. Further, GLP-1 RAs represent a significant advance in T2DM treatment because they uniquely affect a broad array of CV risk factors through significant weight and systolic blood pressure reduction, improved lipid levels, and possibly, as shown in in vitro studies and animal models, through direct effects on cardiac myocytes and endothelium.

Low dose liraglutide in Indian patients with type 2 diabetes in the real world setting

Liraglutide, a human glucagon-like peptide-1 receptor agonist, decreases glycosylated hemoglobin and causes weight loss. However, the cost of therapy and gastrointestinal side- effects such as nausea and diarrhea are important impediments to adherence and long-term compliance. We assessed the efficacy, safety and tolerability of low dose (0.6 mg) liraglutide in obese uncontrolled longstanding type 2 diabetes in Indian patients. Low dose liraglutide improved glycemic control and decreased weight. However, there was a significant drop out because of gastrointestinal intolerance and financial constraints.

Choice of early treatment regimen and impact on β-cell preservation in type 2 diabetes

The progressive deterioration of glycaemic control in individuals with type 2 diabetes mellitus (T2DM) results from insulin resistance combined with the ongoing loss of β-cell function. Although it had been suggested that most β-cell dysfunction occurs after the development of T2DM, studies have documented a substantial early loss of β-cell function, particularly during the prediabetic state. In patients diagnosed with T2DM, β-cell function continues to decline despite treatment with commonly prescribed antihyperglycaemic medications, and ultimately exogenous insulin administration is required to maintain optimal glycaemic control. Thus, interventions to address the early decline in β-cell function could potentially alter the course of T2DM, preventing or delaying its onset and decreasing the incidence of complications. Original research and review articles on this topic were identified in a PubMed search from January 2000 through August 2012. Data from prospective studies and clinical trials suggest that lifestyle modifications and certain antihyperglycaemic medications, including thiazolidinediones (TZDs), glucagon-like peptide-1 (GLP-1) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors and insulin, may preserve or enhance β-cell function. The implication of current data is that early initiation of lifestyle modifications and antihyperglycaemic agents that preserve β-cell function might reverse or delay progression to T2DM in those with prediabetes. Moreover, improved β-cell function may confer more durable glucose control and perhaps reduce/delay the incidence of diabetic complications. Long-term studies are needed to validate this hypothesis.

Glucagon-like peptide-1 analogues: An overview

Abnormalities of the incretin axis have been implicated in the pathogenesis of type 2 diabetes mellitus. Glucagon-like peptide-1 (GLP-1) and gastroinhibitory intestinal peptide constitutes >90% of all the incretin function. Augmentation of GLP-1 results in improvement of beta cell health in a glucose-dependant manner (post-prandial hyperglycemia) and suppression of glucagon (fasting hyperglycemia), amongst other beneficial pleiotropic effects. Native GLP-1 has a very short plasma half-life and novel methods have been developed to augment its half life, such that its anti-hyperglycemic effects can be exploited. They can be broadly classified as exendin-based therapies (exenatide, exenatide once weekly), DPP-4-resistant analogues (lixisenatide, albiglutide), and analogues of human GLP-1 (liraglutide, taspoglutide). Currently, commercially available analogues are exenatide, exenatide once weekly, and liraglutide. This review aims to provide an overview of most GLP-1 analogues.

Exenatide once weekly improved glycaemic control, cardiometabolic risk factors and a composite index of an HbA1c < 7%, without weight gain or hypoglycaemia, over 52 weeks

AIMS

Type 2 diabetes mellitus (T2DM) is often associated with cardiovascular (CV) risk factors such as obesity, hypertension and dyslipidemia. The objective of this analysis was to evaluate potential effects of exenatide once weekly (ExQW), a GLP-1 receptor agonist, on glycaemic control and CV risk factors.

METHODS

This analysis included 675 Intent-to-Treat patients with T2DM [baseline (mean ± SD) HbA1c, 8.1 ± 1.2%; fasting blood glucose (FBG), 166 ± 48 mg/dl; weight, 94.3 ± 19.4 kg; systolic/diastolic blood pressure (SBP/DBP), 129 ± 15/78 ± 9 mm Hg; total cholesterol, 178.5 ± 41.9 mg/dl; low-density lipoprotein (LDL), 100.1 ± 35.0 mg/dl; high-density lipoprotein (HDL), 44.5 ± 11.6 mg/dl; triglycerides, 155.6 ± 3.3 mg/dl; alanine aminotransferase (ALT), 32.1 ± 19.5 U/l] treated with diet and exercise alone or in combination with metformin, sulfonylurea, and/or thiazolidinedione who received 52 weeks of ExQW in four clinical trials.

RESULTS

At 52 weeks, ExQW significantly improved HbA1c [mean (SE) change from baseline, -1.3 (0.05)%], FBG [-36.3 (2.02) mg/dl], body weight [-2.6 (0.19) kg], SBP/DBP [-3.6 (0.56) mm Hg/-1.2 (0.34) mm Hg], total cholesterol, -4.4 (1.33) mg/dl; LDL, -2.6 (1.08) mg/dl; HDL, 1.1 (0.31) mg/dl; triglycerides, -7 (1.6)%], and ALT [-4.3 (0.71) IU/l] concentrations, with greater improvements in patients with elevated analyte levels at baseline. Improvements were observed across a range of background antihyperglycaemia therapies. Of patients completing 52 weeks, 19% achieved the composite American Diabetes Association goal (HbA1c < 7.0%, BP < 130/80 mm Hg, LDL < 100 mg/dl), compared to 1% at baseline. Nearly half (48%) achieved HbA1c < 7.0% without weight gain or major/minor hypoglycaemia. Nausea was the most frequent adverse event and was predominantly mild. Hypoglycaemia was infrequent, and more common with a sulfonylurea.

CONCLUSIONS

With 52 weeks of ExQW, patients experienced sustained improvements in glycaemic control and CV risk factors, with an increased likelihood of achieving both a clinically relevant composite outcome (HbA1c < 7% without weight gain or increased risk of hypoglycaemia) and a composite of key therapeutic goals (HbA1c < 7%, BP < 130/80 mm Hg, LDL < 100 mg/dl).

New incretin hormonal therapies in humans relevant to diabetic cats

Incretins (gastric inhibitory polypeptide and glucagon-like peptide 1 [GLP-1]) are hormones released from the gastrointestinal tract during food intake that potentiate insulin secretion. Native GLP-1 is quickly degraded by the enzyme dipeptidylpeptidase-4 (DPP-4), which has led to the development of GLP-1 agonists with resistance to degradation and to inhibitors of DPP-4 activity as therapeutic agents in humans with type 2 diabetes. In healthy cats, GLP-1 agonists and DPP-4 inhibitors have produced a substantial increase in insulin secretion. Although results of clinical studies are not yet available, incretin-based therapy promises to become an important new research area in feline diabetes.

Thyroid safety in patients treated with liraglutide

During the last years, various novel anti-diabetic drugs have considerably enriched the therapeutic armamentarium for subjects with Type 2 diabetes. In the meantime, much interest has recently been focused on the potential cardiovascular and oncological adverse effects of these new therapies. As to glucagon-like peptide 1 (GLP-1) analogs, medullary thyroid tumors were reported to be more common in rodent toxicology studies with liraglutide, although the relevance of this finding in humans has been questioned. Analyses of sequential changes in calcitonin levels in several thousands of subjects did not reveal a relationship between liraglutide therapy and plasma calcitonin. Furthermore, no medullary thyroid cancer has been detected in humans taking liraglutide. Nevertheless, the long-term consequences of sustained GLP-1 receptor activation in the human thyroid remain unknown and deserve further investigation.

Current treatments and strategies for type 2 diabetes: can we do better with GLP-1 receptor agonists?

Abstract Diet, lifestyle modification, and pharmacotherapy with metformin are appropriate initial treatments for many patients with type 2 diabetes (T2DM). However, most individuals do not maintain glycemic control with metformin alone. Addition of other oral antidiabetes drugs (OADs), including sulfonylurea, meglitinide, or thiazolidinedione, is often the next step. Newer options, including incretin-based glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors, offer important benefits as monotherapies or in combination with OADs, with low risk for hypoglycemia. Reductions in glycated hemoglobin (A1C) have been reported among patients treated with GLP-1 RAs (exenatide, -0.8 to -1.1%; liraglutide, -0.8 to -1.6%), as has weight loss (exenatide, -1.6 to -3.1 kg; liraglutide, -1.6 to -3.2 kg). GLP-1 RAs also stimulate β-cell responses and have positive effects on cardiovascular risk factors often present in patients with T2DM. The most common adverse events associated with GLP-1 RAs are nausea, which diminishes over time, and hypoglycemia (when used in combination with a sulfonylurea). A large number of trials demonstrated benefits of GLP-1 RAs, suggesting they could provide suitable treatment options for patients with T2DM.

Glucagon-like peptide-1 analogues for Type 2 diabetes mellitus: current and emerging agents

Novel therapeutic options for type 2 diabetes mellitus based on the action of the incretin hormone glucagon-like peptide (GLP)-1 were introduced in 2005. As injectable GLP-1 receptor agonists acting on the GLP-1 receptor, exenatide and liraglutide are available in many countries. In type 2 diabetes treatment, incretin-based therapies are attractive and more commonly used because of their mechanism of action and safety profile. Stimulation of insulin secretion and inhibition of glucagon secretion by these agents occur in a glucose-dependent manner. Therefore, incretin-based therapies have no intrinsic risk for hypoglycaemia. Furthermore, GLP-1 receptor agonists allow weight loss and lower systolic blood pressure. This review gives a brief overview of the mechanism of action and summarizes the clinical data available on exenatide and liraglutide as established substances. It further highlights the clinical study data of exenatide once weekly as the first long-acting GLP-1 receptor agonist and covers other new long acting GLP-1 receptor agonists currently in clinical development. The placement of GLP-1 receptor agonists in the treatment algorithm of type 2 diabetes is discussed.

GLP-1 agonists and dipeptidyl-peptidase IV inhibitors

Novel therapeutic options for type 2 diabetes based on the action of the incretin hormone glucagon-like peptide-1 (GLP-1) were introduced in 2005. Incretin-based therapies consist of two classes: (1) the injectable GLP-1 receptor agonists solely acting on the GLP-1 receptor and (2) dipeptidyl-peptidase inhibitors (DPP-4 inhibitors) as oral medications raising endogenous GLP-1 and other hormone levels by inhibiting the degrading enzyme DPP-4. In type 2 diabetes therapy, incretin-based therapies are attractive and more commonly used due to their action and safety profile. Stimulation of insulin secretion and inhibition of glucagon secretion by the above-mentioned agents occur in a glucose-dependent manner. Therefore, incretin-based therapies have no intrinsic risk for hypoglycemias. GLP-1 receptor agonists allow weight loss; DPP-4 inhibitors are weight neutral. This review gives an overview on the mechanism of action and the substances and clinical data available.

Emergence of promising therapies in diabetes mellitus

Diabetes mellitus (DM) results from defects in insulin secretion (type 1) or insulin resistance (type 2). Insulin is used to manage type 1 DM, and oral hypoglycemic agents are used to manage type 2 DM. These therapies are inconsistent in maintaining glycemic control and cause some severe adverse effects such as undue weight gain and hypoglycemia. New and appropriate therapies are needed to overcome these problems. Drugs that are in the pipeline include oral insulins for type 1 DM and incretin mimetics, incretin enhancers, gastric inhibitory peptides, amylin analogues, peroxisome proliferator-activated receptor-α/γ ligands, sodium-dependent glucose transporter inhibitors, and fructose 1,6-bisphosphatase inhibitors for type 2 DM. This article describes the mechanisms of action and relative advantages and disadvantages of the promising therapies.

The evolving place of incretin-based therapies in type 2 diabetes

Treatment options for type 2 diabetes based on the action of the incretin hormone glucagon-like peptide-1 (GLP-1) were first introduced in 2005. These comprise the injectable GLP-1 receptor agonists solely acting on the GLP-1 receptor on the one hand and orally active dipeptidyl-peptidase inhibitors (DPP-4 inhibitors) raising endogenous GLP-1 and other hormone levels by inhibiting the degrading enzyme DPP-4. In adult medicine, both treatment options are attractive and more commonly used because of their action and safety profile. The incretin-based therapies stimulate insulin secretion and inhibit glucagon secretion in a glucose-dependent manner and carry no intrinsic risk of hypoglycaemia. GLP-1 receptor agonists allow weight loss, whereas DPP-4 inhibitors are weight neutral. This review gives an overview of the mechanism of action and the substances and clinical data available.

Liraglutide versus sitagliptin for patients with type 2 diabetes who did not have adequate glycaemic control with metformin: a 26-week, randomised, parallel-group, open-label trial

BACKGROUND

Agonists of the glucagon-like peptide-1 (GLP-1) receptor provide pharmacological levels of GLP-1 activity, whereas dipeptidyl peptidase-4 (DPP-4) inhibitors increase concentrations of endogenous GLP-1 and glucose-dependent insulinotropic polypeptide. We aimed to assess the efficacy and safety of the human GLP-1 analogue liraglutide versus the DPP-4 inhibitor sitagliptin, as adjunct treatments to metformin, in individuals with type 2 diabetes who did not achieve adequate glycaemic control with metformin alone.

METHODS

In this parallel-group, open-label trial, participants (aged 18-80 years) with type 2 diabetes mellitus who had inadequate glycaemic control (glycosylated haemoglobin [HbA(1c)] 7.5-10.0%) on metformin (>or=1500 mg daily for >or=3 months) were enrolled and treated at office-based sites in Europe, the USA, and Canada. Participants were randomly allocated to receive 26 weeks' treatment with 1.2 mg (n=225) or 1.8 mg (n=221) subcutaneous liraglutide once daily, or 100 mg oral sitagliptin once daily (n=219). The primary endpoint was change in HbA(1c) from baseline to week 26. The efficacy of liraglutide versus sitagliptin was assessed hierarchically by a non-inferiority comparison, with a margin of 0.4%, followed by a superiority comparison. Analyses were done on the full analysis set with missing values imputed by last observation carried forward; seven patients assigned to liraglutide did not receive treatment and thus did not meet criteria for inclusion in the full analysis set. This trial is registered with ClinicalTrials.gov, number NCT00700817.

FINDINGS

Greater lowering of mean HbA(1c) (8.5% at baseline) was achieved with 1.8 mg liraglutide (-1.50%, 95% CI -1.63 to -1.37, n=218) and 1.2 mg liraglutide (-1.24%, -1.37 to -1.11, n=221) than with sitagliptin (-0.90%, -1.03 to -0.77, n=219). Estimated mean treatment differences for liraglutide versus sitagliptin were -0.60% (95% CI -0.77 to -0.43, p<0.0001) for 1.8 mg and -0.34% (-0.51 to -0.16, p<0.0001) for 1.2 mg liraglutide. Nausea was more common with liraglutide (59 [27%] patients on 1.8 mg; 46 [21%] on 1.2 mg) than with sitagliptin (10 [5%]). Minor hypoglycaemia was recorded in about 5% of participants in each treatment group.

INTERPRETATION

Liraglutide was superior to sitagliptin for reduction of HbA(1c), and was well tolerated with minimum risk of hypoglycaemia. These findings support the use of liraglutide as an effective GLP-1 agent to add to metformin.

FUNDING

Novo Nordisk.

Glycaemic control in type 2 diabetes: targets and new therapies

Type 2 diabetes mellitus (T2DM) is a worldwide public health challenge. Despite the availability of many antidiabetes agents and pharmacotherapies targeting cardiovascular risk factors, the morbidity, mortality and economic consequences of T2DM are still a great burden to patients, society, health care systems and the economy. The need for new therapies for glycaemic control is compounded by the fact that existing treatments have limitations either because of their side effects (particularly weight gain and hypoglycaemia) or contraindications that limit their use. Furthermore, none of the current therapies have a significant impact on disease progression. Incretin-based therapies offer a new therapeutic approach to the management of T2DM, and there are also several even newer therapies in development. There are two groups of incretin-based therapies currently available; dipeptidyl peptidase-4 (DPP-4) inhibitors and GLP-1 analogues/mimetics. The former are given orally while the latter subcutaneously. These drugs result in glucose-dependent insulin secretion and glucose-dependent glucagon suppression, with consequent low risk of hypoglycaemia when used as mono- or combination therapy (except when used with sulphonylureas). In addition, they are either weight neutral in the case of DPP-4 inhibitors or cause weight loss in the case of incretin mimetics/analogues. Furthermore, animal studies have shown that these agents prolong beta cell survival which offers the theoretical possibility of slowing the progression to T2DM. In this article we will review the currently available antidiabetes agents with particular emphasis on incretin-based and future therapies. In addition, we will review and discuss the evidence relating to glycaemic control and cardiovascular disease.