Liraglutide as adjunct to insulin treatment in type 1 diabetes does not interfere with glycaemic recovery or gastric emptying rate during hypoglycaemia: A randomized, placebo-controlled, double-blind, parallel-group study

Mechanistic Pathways and Clinical Implications of GLP-1 Receptor Agonists in Type 1 Diabetes Management

GLP-1 receptor agonists, which were initially intended to treat type 2 diabetes patients, have demonstrated promise as an adjuvant therapy for type 1 diabetes (T1D). These medications can manage T1D by improving β-cell function, reducing glucose fluctuation, and providing cardioprotective effects. Recent research suggests that boosting cell proliferation and lowering apoptosis can help maintain the bulk of β-cells. Furthermore, GLP-1 receptor agonists have potent anti-inflammatory characteristics, improving immunological control and lowering systemic inflammation, both of which are critical for reducing autoimmune damage in T1D. Beyond glucose control, these agonists have neuroprotective qualities and aid in weight management. Combining these medications with insulin could significantly change how T1D is managed. The clinical data and biological mechanisms discussed in this review support the potential use of GLP-1 receptor agonists in T1D.

Quantified Metrics of Gastric Emptying Delay by Glucagon-Like Peptide-1 Agonists: A Systematic Review and Meta-Analysis With Insights for Periprocedural Management

INTRODUCTION

Divergent recommendations for periprocedural management of glucagon-like peptide-1 (GLP-1) receptor agonist (GLP-1 RA) medications rely on limited evidence. We performed a systematic review and meta-analysis to provide quantitative measures of gastric emptying relevant to mechanisms of weight loss and to periprocedural management of GLP-1 RA. We hypothesized that the magnitude of gastric emptying delay would be low and of limited clinical significance to procedural sedation risks.

METHODS

A protocolized search identified studies on GLP-1 RA that quantified gastric emptying measures. Pooled estimates using random effects were presented as a weighted mean difference with 95% confidence intervals (CIs). Univariate meta-regression was performed to assess the influence of GLP-1 RA type, short-acting vs long-acting mechanism of action, and duration of treatment on gastric emptying.

RESULTS

Fifteen studies met the inclusion criteria. Five studies (n = 247) utilized gastric emptying scintigraphy. Mean T 1/2 was 138.4 minutes (95% CI 74.5-202.3) for GLP-1 RA vs 95.0 minutes (95% CI 54.9-135.0) for placebo, with a pooled mean difference of 36.0 minutes (95% CI 17.0-55.0, P < 0.01, I2 = 79.4%). Ten studies (n = 411) utilized the acetaminophen absorption test, with no significant delay in gastric emptying measured by T max , area under the curve (AUC) 4hr , and AUC 5hr with GLP-1 RA ( P > 0.05). On meta-regression, the type of GLP-1 RA, mechanism of action, and treatment duration did not impact gastric emptying ( P > 0.05).

DISCUSSION

While a gastric emptying delay of ∼36 minutes is quantifiable on GLP-1 RA medications, it is of limited magnitude relative to standard periprocedural fasting periods. There were no substantial differences in gastric emptying on modalities reflective of liquid emptying (acetaminophen absorption test), particularly at time points relevant to periprocedural care.

Benefits and risks of drug combination therapy for diabetes mellitus and its complications: a comprehensive review

Diabetes is a chronic metabolic disease, and its therapeutic goals focus on the effective management of blood glucose and various complications. Drug combination therapy has emerged as a comprehensive treatment approach for diabetes. An increasing number of studies have shown that, compared with monotherapy, combination therapy can bring significant clinical benefits while controlling blood glucose, weight, and blood pressure, as well as mitigating damage from certain complications and delaying their progression in diabetes, including both type 1 diabetes (T1D), type 2 diabetes (T2D) and related complications. This evidence provides strong support for the recommendation of combination therapy for diabetes and highlights the importance of combined treatment. In this review, we first provided a brief overview of the phenotype and pathogenesis of diabetes and discussed several conventional anti-diabetic medications currently used for the treatment of diabetes. We then reviewed several clinical trials and pre-clinical animal experiments on T1D, T2D, and their common complications to evaluate the efficacy and safety of different classes of drug combinations. In general, combination therapy plays a pivotal role in the management of diabetes. Integrating the effectiveness of multiple drugs enables more comprehensive and effective control of blood glucose without increasing the risk of hypoglycemia or other serious adverse events. However, specific treatment regimens should be tailored to individual patients and implemented under the guidance of healthcare professionals.

Incretins beyond type 2 diabetes

Incretin-based therapies, in particular glucagon-like peptide-1 (GLP-1) receptor agonists, have been evaluated in other forms of diabetes, but randomised controlled trials are mainly limited to people living with type 1 diabetes. In this review we present the evidence issuing from these trials and discuss their clinical implications as well as the difficulties in interpreting the data. In type 1 diabetes, the addition of GLP-1 receptor agonists to intensive insulin therapy lowers weight and required insulin doses compared with placebo, but the effects on glucose control (HbA1c, risk of hypoglycaemia) are dependent on the different study protocols. Side effects are limited to the gastrointestinal complaints of nausea, vomiting and diarrhoea. We briefly discuss the potential for using GLP-1 receptor agonists as (adjunct) therapies in other forms of diabetes, where the evidence to date is scarce.

The role of gastric emptying in glucose homeostasis and defense against hypoglycemia: Innocent bystander or partner in crime?

Maintenance of plasma glucose (PG) homeostasis is due to a complex network system. Even a minor fall in PG activates multiple neuroendocrine actions promoting hormonal, metabolic and behavioral responses, which prevent and ultimately recover hypoglycemia, primarily neuroglycopenia. Among these responses, gastric emptying (GE) plays an important role by coordinated mechanisms which regulate transit and absorption of nutrients through the small intestine. A bidirectional relationship between GE and glycemia has been established: GE may explain the up to 30-40 % variance in glycemic response following a carbohydrate-rich meal. In addition, acute and chronic hyperglycemia induce deceleration of GE after meals. Hypoglycemia accelerates GE, but its role in counterregulation has been poorly investigated. The role of GE as a counterregulatory mechanism has been confirmed in pathophysiological conditions, such as gastroparesis or following recurrent hypoglycemia. Therefore, it could represent an "ancestral" mechanism, highly conservative and effective in all individuals, conditions and clinical contexts. Recent guidelines recommend GLP-1 receptor agonists (GLP-1RAs) either as the first injectable therapy for type 2 diabetes mellitus or in combination with insulin. Considering the potential impact on GE, it would be important to study subjects on GLP-1 RAs during hypoglycemia, to establish whether a possible deceleration of GE impairs glucose counterregulation.

Semaglutide delays 4-hour gastric emptying in women with polycystic ovary syndrome and obesity

AIM

To evaluate the effect of once-weekly subcutaneous semaglutide 1.0 mg on the late digestive period of gastric emptying (GE) after ingestion of a standardized solid test meal by using technetium scintigraphy, the reference method for this purpose.

METHODS

We conducted a single-blind, placebo-controlled trial in 20 obese women with polycystic ovary syndrome (PCOS; mean [range] age 35 [32.3-40.8] years, body mass index 37 [30.7-39.8] kg/m² ) randomized to subcutaneous semaglutide 1.0 mg once weekly or placebo for 12 weeks. GE was assessed after ingestion of [^99mT c] colloid in a pancake labelled with radiopharmaceutical by scintigraphy using sequential static imaging and dynamic acquisition at baseline and at Week 13. Estimation of GE was obtained by repeated imaging of remaining [^99mT c] activity at fixed time intervals over the course of 4 hours after ingestion.

RESULTS

From baseline to the study end, semaglutide increased the estimated retention of gastric contents by 3.5% at 1 hour, 25.5% at 2 hours, 38.0% at 3 hours and 30.0% at 4 hours after ingestion of the radioactively labelled solid meal. Four hours after ingestion, semaglutide retained 37% of solid meal in the stomach compared to no gastric retention in the placebo group (P = 0.002). Time taken for half the radiolabelled meal to empty from the stomach was significantly longer in the semaglutide group than the placebo group (171 vs. 118 min; P < 0.001).

CONCLUSION

Semaglutide markedly delayed 4-hour GE in women with PCOS and obesity.

Factors associated with successful weight loss after liraglutide treatment for obesity

AIM

To identify patient factors, including gastrointestinal functions, that are predictive or associated with weight loss in response to once-daily 3 mg liraglutide administered subcutaneously (SQ) or placebo in obesity.

METHODS

One hundred and thirty-six obese adults (87% female) were randomized in a placebo-controlled, 16-week trial of liraglutide, escalated to 3 mg administered SQ daily. Gastrointestinal functions were measured at baseline and 16 weeks: gastric emptying of solids (GET1/2 ); fasting and postprandial gastric volumes; kcal ingested during ad libitum buffet meal and the nutrient drink test. GET1/2 was also measured at 5 weeks. A multiple variable regression model examined variables associated with weight loss of more than 4 kg at 16 weeks. A parsimonious model using backward selection identified the final model.

RESULTS

Weight loss of more than 4 kg at 16 weeks occurred in 71% of liraglutide- and 16% of placebo-treated patients. In all participants combined, parameters univariately associated with a weight loss of more than 4 kg were GET1/2 at 5 and 16 weeks, weight loss at 5 weeks and kcal intake during the buffet meal at 16 weeks. The final parsimonious model (area under the receiver operator characteristics [AUROC] curve = 0.832) identified that factors associated with more than 4-kg weight loss were GET1/2 at 5 weeks (OR = 2.505; 95% CI: 1.57-3.997) per 50 minutes and kcal intake during ad libitum meal at 16 weeks (OR = 0.721; 95% CI: 0.602-0.864) per 100 kcal. Among only the 60 liraglutide-treated subjects, kcal intake at 16 weeks was associated with 4-kg weight loss (AUROC = 0.757).

CONCLUSIONS

Slower GET1/2 and weight loss at 5 weeks predicted a weight loss of more than 4 kg at 16 weeks in all participants. Among liraglutide-treated adults, weight loss of more than 4 kg was associated with ad libitum meal kcal intake at 16 weeks.

Effect of Liraglutide Treatment on Whole-body Glucose Fluxes in C-peptide-Positive Type 1 Diabetes During Hypoglycemia

CONTEXT

The effect of liraglutide in C-peptide-positive (C-pos) type 1 diabetes (T1D) patients during hypoglycemia remains unclear.

OBJECTIVE

To investigate the effect of a 12-week liraglutide treatment on the body glucose fluxes during a hypoglycemic clamp in C-pos T1D patients and its impact on the alpha- and beta-cell responses during hypoglycemia.

DESIGN

This was a randomized, double-blind, crossover study. Each C-pos T1D patient was allocated to the treatment sequence liraglutide/placebo or placebo/liraglutide with daily injections for 12 weeks adjunct to insulin treatment, separated by a 4-week washout period.

SETTING AND PARTICIPANTS

Fourteen T1D patients with fasting C-peptide ≥ 0.1 nmol/L.

INTERVENTION(S)

All patients underwent a hyperinsulinemic-stepwise-hypoglycemic clamp with isotope tracer [plasma glucose (PG) plateaus: 5.5, 3.5, 2.5, and 3.9 mmol/L] after a 3-month liraglutide (1.2 mg) or placebo treatment.

MAIN OUTCOME MEASURE(S)

The responses of endogenous glucose production (EGP) and rate of peripheral glucose disposal (Rd) were similar for liraglutide and placebo treatment during the clamp.

RESULTS

The numbers of hypoglycemic events were similar in both groups. At the clamp, mean glucagon levels were significantly lower at PG plateau 5.5 mmol/L in the liraglutide than in the placebo group but showed similar responses to hypoglycemia in both groups. Mean C-peptide levels were significantly higher at PG-plateaus 5.5 and 3.5 mmol/L after liraglutide treatment, but this effect was not reflected in EGP and Rd. Hemoglobin A1c and body weight were lower, and a trend for reduced insulin was seen after liraglutide treatment.

CONCLUSIONS

The results indicate that 3 months of liraglutide treatment does not promote or prolong hypoglycemia in C-pos T1D patients.

Effects of liraglutide on gastrointestinal functions and weight in obesity: A randomized clinical and pharmacogenomic trial

OBJECTIVE

This study aimed to determine the effects of a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, and placebo subcutaneously over 16 weeks on weight and gastric functions and to evaluate associations of single-nucleotide polymorphisms in GLP1R (rs6923761) and TCF7L2 (rs7903146) with effects of liraglutide.

METHODS

The study conducted a randomized, parallel-group, placebo-controlled, 16-week trial of liraglutide, escalated to 3 mg subcutaneously daily in 136 otherwise healthy adults with obesity. Weight, gastric emptying of solids (GES), gastric volumes, satiation, and body composition measured at baseline and after treatment were compared in two treatment groups using analysis of covariance.

RESULTS

Liraglutide (n = 59) and placebo (n = 65) groups completed treatment. Relative to placebo, liraglutide increased weight loss at 5 and 16 weeks (both p < 0.05), slowed time to half GES (T1/2 ) at 5 and 16 weeks (both p < 0.001), and increased fasting gastric volume (p = 0.01) and satiation (p < 0.01) at 16 weeks. GES T1/2 was positively correlated with weight loss on liraglutide (both p < 0.001). After 16 weeks of liraglutide, GLP1R rs6923761 (AG/AA vs. GG) was associated with reduced percent body fat (p = 0.062), and TCF7L2 rs7903146 (CC vs. CT/TT) was associated with lower body weight (p = 0.015).

CONCLUSIONS

Liraglutide, 3 mg, induces weight loss with delay in GES T1/2 and reduces calorie intake. Slowing GES and variations in GLP1R and TCF7L2 are associated with liraglutide effects in obesity.

Glucagon-like peptide-1 receptor agonists as adjunctive treatment for type 1 diabetes: Renewed opportunities through tailored approaches?

Exogenous insulin has been the mainstay treatment for individuals living with type 1 diabetes (T1D). Although there has been tremendous growth in both pharmacological and technological advancements, insulin monotherapy has proven to be insufficient for maintaining optimal glycaemic targets for most adults with T1D. At present, there is still no breakthrough for the treatment of T1D. Adjunctive pharmacotherapies might therefore complement insulin management to achieve better glycaemic control, while possibly offering additional benefits. Recent interest in re-purposing glucagon-like peptide-1 receptor agonists (GLP-1RAs), a leading antihyperglycaemic medication class approved for type 2 diabetes, has prompted the field to seek extended potential for the T1D population. The adjunctive use of GLP-1RAs has been at the forefront of T1D research, albeit with some conflicting trial findings to date. However, the potential of GLP-1 agonism for T1D may have been underestimated, possibly from missed opportunities or categorized effects. Moreover, some GLP-1RAs have demonstrated extra-pancreatic potential with emerging multi-organ protection involving the heart, kidneys, liver and brain in varied cohorts, which may bode well for the growing T1D profile of comorbid complications. This narrative review aims to summarize and critically appraise the current evidence-based literature from large-scale randomized controlled trials and closed-loop system pilot studies that examined GLP-1RAs as adjunctive therapy for T1D. Furthermore, we outline uncharted opportunities with GLP-1 agonism using versatile approaches in selected T1D populations that may inspire and re-direct future research in this field.

Using adjuvant pharmacotherapy in the treatment of type 1 diabetes

Introduction: Insulin and its analogues have so far been the only approved treatment for type 1 diabetes in Europe, while in the U.S. the amylin analog pramlintide is approved for adjuvant use with insulin. However, in clinical practice, various drugs against type 2 diabetes have been used off label with insulin for type 1 diabetes. Recently, the EMA approved the SGLT inhibitors dapagliflozin and sotagliflozin as adjuvant treatments to insulin for type 1 diabetes in adults.Areas covered: This article is a survey of adjuvant treatments used against type 1 diabetes, focusing on SGLT inhibitors.Expert opinion: While GLP-1R agonists and metformin may reduce weight gain associated with insulin therapy and possibly also confer non-glycemic benefits, only the SGLT inhibitors dapagliflozin and sotagliflozin have been approved in Europe as adjunctive to insulin for type 1 diabetes. Since these drugs act independently of insulin, they are very valuable additions to the armamentarium against type 1 diabetes. However, they should be used judiciously in select patients to mitigate the risk of diabetic ketoacidosis. Patients should be instructed to avoid risk situations and be taught to measure blood ketones themselves.

A systematic review and dose-response meta-analysis on the efficacy of dapagliflozin in patients with type 1 diabetes mellitus

Formulation of insulin analogs and its delivery are developed in over recent years but glycemic control in most patients with type-1 diabetes mellitus (DM) is not adequate yet. The aim of this meta-analysis is to evaluate the efficacy of dapagliflozin in patients with type-1 DM. The MEDLINE/PubMed, Scopus, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science databases were searched up to Aug 2020 to identify the potential literature. Random-effects model (DerSimonian and Laird method) was used to estimate the pooled effect size as weighted mean difference (WMD) with 95 % confidence interval (CI). Five randomized placebo-controlled trials with 11 arms were included in the quantitative analysis. The pooled results suggested a significant reduction in glycated hemoglobin A1C (HbA1C; WMD: -0.36 %, 95 % CI: -0.55, -0.18), body weight (WMD: -4.02 kg, 95 % CI: -4.78, -3.25), and total daily insulin dose (TDID; WMD: -10.36 %, 95 % CI: -13.42, -7.29), as well as an increase in 24-h urinary glucose excretion (24-h UGE; WMD: 90.02 g/24-h, 95 % CI: 72.96, 107.09) in dapagliflozin group compared to control group. Dose of dapagliflozin had a significant effect on body weight reduction (Coef = -3.7, p = 0.01) and 24-h UGE (coef = 0.85, p = 0.005). Pooled results of this meta-analysis identified a significant reduction in HbA1c levels, body weight, and TDID, and a substantial increase in 24-h UGE in patients who received dapagliflozin versus placebo.

Age, sex, disease severity, and disease duration difference in placebo response: implications from a meta-analysis of diabetes mellitus

BACKGROUND

The placebo response in patients with diabetes mellitus is very common. A systematic evaluation needs to be updated with the current evidence about the placebo response in diabetes mellitus and the associated factors in clinical trials of anti-diabetic medicine.

METHODS

Literature research was conducted in Medline, Embase, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for studies published between the date of inception and June 2019. Randomized placebo-controlled trials conducted in type 1and type 2 diabetes mellitus (T1DM/T2DM) were included. Random-effects model and meta-regression analysis were accordingly used. This meta-analysis was registered in PROSPERO as CRD42014009373.

RESULTS

Significantly weight elevation (effect size (ES) = 0.33 kg, 95% CI, 0.03 to 0.61 kg) was observed in patients with placebo treatments in T1DM subgroup while significantly HbA1c reduction (ES = - 0.12%, 95% CI, - 0.16 to - 0.07%) and weight reduction (ES = - 0.40 kg, 95% CI, - 0.50 to - 0.29 kg) were observed in patients with placebo treatments in T2DM subgroup. Greater HbA1c reduction was observed in patients with injectable placebo treatments (ES = - 0.22%, 95% CI, - 0.32 to - 0.11%) versus oral types (ES = - 0.09%, 95% CI, - 0.14 to - 0.04%) in T2DM (P = 0.03). Older age (β = - 0.01, 95% CI, - 0.02 to - 0.01, P < 0.01) and longer diabetes duration (β = - 0.02, 95% CI, - 0.03 to - 0.21 × 10^-2, P = 0.03) was significantly associated with more HbA1c reduction by placebo in T1DM. However, younger age (β = 0.02, 95% CI, 0.01 to 0.03, P = 0.01), lower male percentage (β = 0.01, 95% CI, 0.22 × 10^-2, 0.01, P < 0.01), higher baseline BMI (β = - 0.02, 95% CI, - 0.04 to - 0.26 × 10^-2, P = 0.02), and higher baseline HbA1c (β = - 0.09, 95% CI, - 0.16 to - 0.01, P = 0.02) were significantly associated with more HbA1c reduction by placebo in T2DM. Shorter diabetes duration (β = 0.06, 95% CI, 0.06 to 0.10, P < 0.01) was significantly associated with more weight reduction by placebo in T2DM. However, the associations between baseline BMI, baseline HbA1c, and placebo response were insignificant after the adjusted analyses.

CONCLUSION

The placebo response in diabetes mellitus was systematically outlined. Age, sex, disease severity (indirectly reflected by baseline BMI and baseline HbA1c), and disease duration were associated with placebo response in diabetes mellitus. The association between baseline BMI, baseline HbA1c, and placebo response may be the result of regression to the mean.

Liraglutide as Adjunct to Insulin Treatment in Patients with Type 1 Diabetes: A Systematic Review and Meta-analysis

BACKGROUND

A few Randomized Controlled Trials (RCTs) have evaluated the use of liraglutide in Type 1 Diabetes (T1D). Through the present systematic review and meta-analysis, we aim at critically appraising and summarizing those RCTs, providing precise effect estimates.

METHODS

We searched major databases and grey literature from their inception to October 2018, for RCTs with a duration ≥ 12 weeks, comparing liraglutide with placebo or any other comparator as adjunct to insulin in patients with T1D, investigating major efficacy and safety endpoints. This review is reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement.

RESULTS

We included 5 trials with 2,445 randomized participants. Liraglutide provided modest reductions in HbA1c, with liraglutide 1.8 mg producing the greatest decrease (MD = -0.24%, 95% CI -0.32 to -0.16, I2=0%). Significant weight reduction, up to 4.87 kg with liraglutide 1.8 mg was also observed (95% CI -5.31 to -4.43, I2=0%). Decrease in total daily insulin dose, primarily driven by a decrease in bolus insulin requirements, was demonstrated. Liraglutide decreased non-significantly the odds for severe hypoglycemia (OR=0.80, 95% CI 0.57-1.14, I2=0%), while it increased significantly the odds for gastrointestinal adverse events (for nausea, OR=4.70, 95% CI 3.68-6.00, I2=37%, and for vomiting, OR=2.50, 95% CI 1.54-4.72, I2=27%). A significant increase in heart rate was also demonstrated. No association with diabetic ketoacidosis or malignancies was identified.

CONCLUSION

In patients with T1D, liraglutide might prove be an adjunct to insulin, improving glycemic control, inducing body weight loss and decreasing exogenous insulin requirements and severe hypoglycemia.

Incretin-based medications (GLP-1 receptor agonists, DPP-4 inhibitors) as a means to avoid hypoglycaemic episodes

Hypoglycaemia is common in both type 1 and type 2 diabetes and has both acute and long-term consequences. Therefore, a key to proper glucose-lowering therapy in diabetes is to avoid or prevent hypoglycaemia. Incretin therapy (DPP-4 inhibitors and GLP-1 receptor agonists) offers an advantage in this respect, because it reduces glucose with a low risk of hypoglycaemia, both in monotherapy and in combination with other therapies. The reason for this low risk of hypoglycaemia is the glucose dependency of action of incretin therapy and the sustainment of glucose counter-regulatory hormone responses to hypoglycaemia, in particular the glucagon response. Incretin therapy is also associated with a low risk of hypoglycaemia in patient groups which are especially vulnerable and susceptible for hypoglycaemia, e.g., subjects with renal impairment, elderly subjects and subjects with on-going insulin therapy. This review summarizes how incretin therapy may meet the challenges of hypoglycaemia and suggests that incretin therapy is a therapy of choice to avoid hypoglycaemia, both in the general diabetes population and in subjects with increased risk or vulnerability for hypoglycaemia.

Effect of the GLP-1 receptor agonist exenatide on impaired awareness of hypoglycemia in type 1 diabetes; a randomized controlled trial

CONTEXT

Impaired awareness of hypoglycemia (IAH), resulting from habituation to recurrent hypoglycemia, can be reversed by strict avoidance of hypoglycemia. Adjunctive treatment with glucagon-like peptide-1 (GLP-1) receptor agonists may reduce glucose variability, hence lower the risk of hypoglycemia and improve awareness. The aim of our study was to investigate the effect of exenatide on awareness of hypoglycemia in people with type 1 diabetes and IAH.

METHODS

This was a randomized double-blind, placebo-controlled cross-over trial. Ten patients with type 1 diabetes and IAH were included (age 38.5±4.4 years, 40% males, HbA1c 7.2±0.4 % (55.2±4.8 mmol/mol)). Patients were treated with exenatide 5µg twice daily (first 2 weeks), followed by 10µg twice daily (remaining 4 weeks) or matching placebo, with a 4-week washout period. Patients wore blinded glucose sensors in the final weeks and modified hyperinsulinemic normoglycemic-hypoglycemic glucose clamps (nadir 2.5 mmol/l) were performed at the end of each treatment period.

RESULTS

Treatment with exenatide caused body weight to fall as compared to placebo (-3.9±0.9 vs. 0.6±1.2 kg, p=0.047). Exenatide did not change mean 24-hour glucose levels (8.3±0.4 vs. 8.5±0.3 mmol/l, exenatide vs. placebo, p=0.64), median (interquartile range) percentage of time spent in hypoglycemia (15.5 [4.5, 25.5] vs. 7.8 [4.4, 17.1]%, p=0.11) and frequency of hypoglycemia (15.8±3.7 vs. 12.1±3.5, p=0.19). Symptom scores in response to clamped hypoglycemia were similar between exenatide (median change 1.0 [-1.5, 7.0]) and placebo (4.5 [1.5, 5.8], p=0.08).

CONCLUSIONS

Six weeks treatment with exenatide did not improve awareness of hypoglycemia in patients with type 1 diabetes and IAH.

Incretin-based therapies for patients with type 1 diabetes: a meta-analysis

OBJECTIVE

Combined treatment with an incretin-based drug, such as a glucagon-like peptide 1 receptor agonist (GLP-1 RA) or a dipeptidyl peptidase-4 (DPP-4) inhibitor, and basal insulin is a new strategy for improving glucose control in type 1 diabetes mellitus (T1DM). We performed a meta-analysis to assess the effect of this combined treatment on glycaemic control, insulin dose, severe hypoglycaemia, weight gain and gastrointestinal side effects in T1DM patients.

METHODS

We searched PubMed, EMBASE and the Cochrane Library for relevant studies published before July 16, 2018. The primary outcome was glycosylated haemoglobin (HbA1c). Secondary outcomes included total daily insulin dose, body weight, severe hypoglycaemia and gastrointestinal side effects.

RESULTS

Nine randomized controlled trials (RCTs) involving 2389 patients were ultimately included in the meta-analysis. The pooled data suggested that incretin-based therapy was associated with a reduction in HbA1c levels (weighted mean difference (WMD) -0.17%, 95% confidence interval (CI) -0.24 to -0.11, P < 0.001), total daily insulin dose (WMD -5.53 IU/day, 95% CI -8.89 to -2.17, P = 0.001) and body weight (WMD -3.24 kg, 95% CI -4.43 to -2.04, P < 0.001). Incretins did not increase the risk of severe hypoglycaemia (odds ratio (OR) 0.83, 95% CI 0.60-1.16, P = 0.287) but increased the occurrence of gastrointestinal side effects (OR 3.46, 95% CI 2.20-5.45, P < 0.001).

CONCLUSIONS

In T1DM patients, GLP-1 RAs, but not DPP-4 inhibitors, combined with insulin appear to be an effective therapy but may increase the occurrence of gastrointestinal side effects.

Metabolic Control in Type 1 Diabetes: Is Adjunctive Therapy the Way Forward?

Despite advances in insulin therapies, patients with type 1 diabetes (T1DM) have a shorter life span due to hyperglycaemia-induced vascular disease and hypoglycaemic complications secondary to insulin therapy. Restricting therapy for T1DM to insulin replacement is perhaps an over-simplistic approach, and we focus in this work on reviewing the role of adjuvant therapy in this population. Current data suggest that adding metformin to insulin therapy in T1DM temporarily lowers HbA1c and reduces weight and insulin requirements, but this treatment fails to show a longer-term glycaemic benefit. Agents in the sodium glucose co-transporter-2 inhibitor (SGLT-2) class demonstrate the greatest promise in correcting hyperglycaemia, but there are safety concerns in relation to the risk of diabetic ketoacidosis. Glucagon-like peptide-1 agonists (GLP-1) show a modest effect on glycaemia, if any, but significantly reduce weight, which may make them suitable for use in overweight T1DM patients. Treatment with pramlintide is not widely available worldwide, although there is evidence to indicate that this agent reduces both HbA1c and weight in T1DM. A criticism of adjuvant studies is the heavy reliance on HbA1c as the primary endpoint while generally ignoring other glycaemic parameters. Moreover, vascular risk markers and measures of insulin resistance-important considerations in individuals with a longer T1DM duration-are yet to be fully investigated following adjuvant therapies. Finally, studies to date have made the assumption that T1DM patients are a homogeneous group of individuals who respond similarly to adjuvant therapies, which is unlikely to be the case. Future longer-term adjuvant studies investigating different glycaemic parameters, surrogate vascular markers and harder clinical outcomes will refine our understanding of the roles of such therapies in various subgroups of T1DM patients.

Do glucagon-like peptide-1 receptor (GLP-1R) agonists have potential as adjuncts in the treatment of type 1 diabetes?

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) is produced by the gut, stimulates insulin secretion from the pancreatic β-cells, and inhibits glucagon secretion from the α-cells. The GLP-1 receptor (GLP-1R) agonists are used in the treatment of type 2 diabetes (T2DM).

AREAS COVERED

This review covers the clinical trials of the GLP-1R agonists (exenatide and liraglutide) and their potential as adjunct treatment in type 1 diabetes mellitus (T1DM).

EXPERT OPINION

GLP-1R agonists are unable to increase insulin secretion, in subjects with T1DM, who are C-peptide negative. Also, the GLP-1R agonists either have no effect or cause a small inhibition of glucagon secretion in subjects with T1DM. There is no evidence that the GLP-1R agonists cause a major reduction in HbA1c, or have a major effect on hypo- or hyperglycemia in subjects with TD1M. The main beneficial effect of the GLP-1R agonists is probably the modest weight loss, which may underlie the reduction in dose of insulin used. Given that the GLP-1R agonists cause gastrointestinal adverse effects, and with reduced insulin doses, increase the risk of ketosis, it seems to me that the risk with these agents may outweigh any benefit in T1DM, and that they have little potential as adjuncts in the treatment of T1DM.

Bidirectional Relationship between Gastric Emptying and Plasma Glucose Control in Normoglycemic Individuals and Diabetic Patients

Gastric emptying and glycemic control pathways are closely interrelated processes. Gastric chyme is transferred into the duodenum with velocities depending on its solid or liquid state, as well as on its caloric and nutritional composition. Once nutrients enter the intestine, the secretion of incretins (hormonal products of intestinal cells) is stimulated. Among incretins, glucagon-like peptide-1 (GLP-1) has multiple glycemic-regulatory effects that include delayed gastric emptying, thus triggering a feedback loop lowering postprandial serum glucose levels. Glycemic values also influence gastric emptying; hyperglycemia slows it down, and hypoglycemia accelerates it, both limiting glycemic fluctuations. Disordered gastric emptying in diabetes mellitus is understood today as a complex pathophysiological condition, with both irreversible and reversible components and high intra- and interindividual variability of time span and clinical features. While limited delays may be useful for reducing postprandial hyperglycemias, severely hindered gastric emptying may be associated with higher glycemic variability and worsened long-term glycemic control. Therapeutic approaches for both gastric emptying and glycemic control include dietary modifications of meal structure or content and drugs acting as GLP-1 receptor agonists. In the foreseeable future, we will probably witness a wider range of dietary interventions and more incretin-based medications used for restoring both gastric emptying and glycemic levels to nearly physiological levels.

Effects of liraglutide on weight, satiation, and gastric functions in obesity: a randomised, placebo-controlled pilot trial

BACKGROUND

Liraglutide, a long-acting GLP-1 receptor agonist, is approved for treatment of obesity; however, the mechanisms of action of liraglutide are incompletely understood. We compared effects of liraglutide versus placebo on gastric motor functions, satiation, satiety, and weight in obese individuals over 16 weeks.

METHODS

We did a randomised, double-blind, placebo-controlled pilot trial at a single centre (Mayo Clinic, Rochester, MN, USA). Participants were randomly allocated (1:1) by a computer generated randomisation schedule with no stratification to receive subcutaneous liraglutide (3·0 mg) or placebo, with standardised nutritional and behavioural counselling. Allocation was concealed from participants and study investigators. Otherwise healthy, local residents aged 18-65 years with body-mass index (BMI) 30 kg/m² or higher were included. Liraglutide or placebo was escalated by 0·6 mg/day each week for 5 weeks and continued until week 16. The primary outcome was change in gastric emptying (delay relative to baseline) of solids T_1/2 (time taken for half the radiolabelled meal to empty from the stomach), measured at 5 weeks and 16 weeks in all patients who received at least one dose of study drug, with missing data imputed. Secondary outcomes included weight loss at weeks 5 and 16, satiation (volume to fullness and maximum tolerated volume), satiety, and fasting and postprandial gastric volumes at 16 weeks. This trial is registered with ClinicalTrials.gov, number NCT02647944, and is closed to new participants.

FINDINGS

Between Dec 18, 2015, and Sept 1, 2016, 40 adults were enrolled and randomly allocated (19 to the liraglutide group; 21 to the placebo group). Compared with placebo, liraglutide delayed gastric emptying of solids at 5 weeks (median 70 min [IQR 32 to 151] vs 4 min [-21 to 18]; p<0·0001) and 16 weeks (30·5 min [-11 to 54] vs -1 min [-19 to 7]; p=0·025). There was also significantly greater weight loss in the liraglutide group than in the placebo group (at 5 weeks: median 3·7 kg [IQR 2·8 to 4·8] vs 0·6 kg [-0·3 to 1·4], p<0·0001; at 16 weeks: 5·3 kg [5·2 to 6·8] vs 2·5 kg [0·1 to 4·2], p=0·0009). Satiation, as assessed by maximum tolerated volume at 16 weeks, was lower in the liraglutide group (median 750 mL [IQR 651 to 908]) compared with the placebo group (1126 mL [944-1185]; p=0·054). No significant differences were noted between groups in terms of volume to fullness, satiety, or fasting and postprandial gastric volumes at week 16. Post-hoc analysis showed that the T_1/2 of gastric emptying of solids at 5 weeks correlated with change in weight loss at week 16 with liraglutide (Rs 0·567, p=0·018). Nausea was the most common adverse event in the liraglutide group (12 of 19) compared with placebo (four of 21).

INTERPRETATION

Effects of liraglutide on weight loss are associated with delay in gastric emptying of solids; measurement of gastric emptying (eg, at 5 weeks of treatment) may be a biomarker of responsiveness and may help to select individuals for prolonged treatment with this class of drug.

FUNDING

US National Institutes of Health grant R56-DK67071.

Short-acting glucagon-like peptide-1 receptor agonists as add-on to insulin therapy in type 1 diabetes: A review

A large proportion of patients with type 1 diabetes do not reach their glycaemic target of glycated hemoglobin (HbA1c) <7.0% (53 mmol/mol) and, furthermore, an increasing number of patients with type 1 diabetes are overweight and obese. Treatment of type 1 diabetes is based on insulin therapy, which is associated with well-described and unfortunate adverse effects such as hypoglycaemia and increased body weight. Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are the focus of increasing interest as a possible adjunctive treatment to insulin in type 1 diabetes because of their glucagonostatic and extrapancreatic effects. So far, the focus has mainly been on the long-acting GLP-1RAs, but the risk-benefit ratio emerging from studies evaluating the effect of long-acting GLP-1RAs as adjunctive therapy to insulin therapy in patients with type 1 diabetes has been disappointing. This might be attributable to a lack of glucagonostatic effect of these long-acting GLP-1RAs in type 1 diabetes, alongside development of tachyphylaxis to GLP-1-induced retardation of gastric emptying. In contrast, the short-acting GLP-1RAs seem to have a preserved and sustained effect on glucagon secretion and gastric emptying in patients with type 1 diabetes, which could translate into effective lowering of postprandial glucose excursions; however, these observations regarding short-acting GLP-1RAs are all derived from small open-label trials and should thus be interpreted with caution. In the present paper we review the potential role of GLP-1RAs, in particular short-acting GLP-1RAs, as add-on to insulin in the treatment of type 1 diabetes.