Glycemic variability in newly diagnosed diabetic cats treated with the glucagon-like peptide-1 analogue exenatide extended release

Incretin therapy in feline diabetes mellitus - A review of the current state of research

Incretin hormones potentiate the glucose-induced insulin secretion following enteral nutrient intake. The best characterised incretin hormones are glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) which are produced in and secreted from the gut in response to nutrient ingestion. The property of incretins to enhance endogenous insulin secretion only at elevated blood glucose levels makes them interesting therapeutics for type 2 diabetes mellitus with a better safety profile than exogenous insulin. While incretin therapeutics (especially GLP-1 agonists, and more recently also GLP-1 / GIP dual agonists and other drugs that influence the incretin metabolism (e.g., dipeptidyl peptidase-4 (DPP-4) inhibitors)) are already widely used treatment options for human type 2 diabetes, these drugs are not yet approved for the therapy of feline diabetes mellitus. This review provides an introduction to incretins and feline diabetes mellitus in general and summarises the current study situation on incretins as therapeutics for feline diabetes mellitus to assess their possible future potential in feline medicine. Studies to date on the use of GLP-1 receptor agonists (GLP-1RA) in healthy cats largely confirm their insulinotropic effect known from other species. In diabetic cats, GLP-1RAs appear to significantly reduce glycaemic variability (GV, an indicator for the quality of glycaemic control), which is important for the management of the disease and prevention of long-term complications. However, for widespread use in feline diabetes mellitus, further studies are required that include larger numbers of diabetic cats, and that consider and test a possible need for dose adjustments to overweight and diabetic cats. Also evaluation of the outcome of GLP-1RA monotherapy will be neceessary.

Drug release profile of a novel exenatide long-term drug delivery system (OKV-119) administered to cats

Beneficial weight-loss properties of glucagon-like peptide-1 receptor agonists (GLP-1RA) in obese people, with corresponding improvements in cardiometabolic risk factors, are well established. OKV-119 is an investigational drug delivery system that is being developed for the long-term delivery of the GLP-1RA exenatide to feline patients. The purpose of this study was to evaluate the drug release characteristics of subcutaneous OKV-119 implants configured to release exenatide for 84 days. Following a 7-day acclimation period, five purpose-bred cats were implanted with OKV-119 protypes and observed for a 112-day study period. Food intake, weekly plasma exenatide concentrations and body weight were measured. Exenatide plasma concentrations were detected at the first measured timepoint (Day 7) and maintained above baseline for over 84 Days. Over the first 28 days, reduced caloric intake and a reduction in body weight were observed in four of five cats. In these cats, a body weight reduction of at least 5% was maintained throughout the 112-day study period. This study demonstrates that a single OKV-119 implant can deliver the GLP-1RA exenatide for a months long duration. Results suggest that exposure to exenatide plasma concentrations ranging from 1.5 ng/ml to 4 ng/ml are sufficient for inducing weight loss in cats.

Advances in Drug Treatments for Companion Animal Obesity

Companion animal obesity has emerged as a significant veterinary health concern globally, with escalating rates posing challenges for preventive and therapeutic interventions. Obesity not only leads to immediate health problems but also contributes to various comorbidities affecting animal well-being and longevity, with consequent emotional and financial burdens on owners. While past treatment strategies have shown limited success, recent breakthroughs in human medicine present new opportunities for addressing this complex issue in companion animals. Here, we discuss the potential of GLP-1 receptor agonists, specifically semaglutide and tirzepatide, already approved for human use, for addressing companion animal obesity. These drugs, originally developed to treat type 2 diabetes in humans and subsequently repurposed to treat obesity, have demonstrated remarkable weight loss effects in rodents, non-human primates and people. Additionally, newer drug combinations have shown even more promising results in clinical trials. Despite current cost and supply challenges, advancements in oral and/or extended-release formulations and increased production may make these drugs more accessible for veterinary use. Thus, these drugs may have utility in companion animal weight management, and future feasibility studies exploring their efficacy and safety in treating companion animal obesity are warranted.

Insulin release from isolated cat islets of Langerhans

Feline diabetes mellitus is a common endocrine disease with increasing prevalence. It shows similarities with human type 2 diabetes and is characterized by insulin resistance and deficient insulin secretion. Moreover, cats and humans belong to the very few species that form amyloid depositions in the pancreatic islets. However, little is known about cat islet function and no studies have addressed insulin secretion from isolated islets ex vivo. The aim of this study was to establish a protocol for isolation of islets of Langerhans from pancreata of cats euthanized due to disease, and to evaluate insulin secretion responses to various physiological and pharmacological stimuli. Collagenase digestion of pancreatic tissue from 13 non-diabetic cats and two cats with diabetic ketoacidosis yielded individual islets surrounded by a layer of exocrine tissue that was reduced after two days in culture. Histological examination showed islet amyloid in pancreatic biopsies from most non-diabetic and in one diabetic cat. Islets from non-diabetic cats cultured at 5.5 mM glucose responded with increased insulin secretion to 16.7 mM glucose, 30 mM K+ and 20 µM of the sulfonylurea glipizide (2-3 times basal secretion at 3 mM glucose). The glucagon-like peptide-1 receptor agonist exendin-4 (100 nM) had no effect under basal conditions but potentiated glucose-triggered insulin release. Only one of nine islet batches from diabetic cats released detectable amounts of insulin, which was enhanced by exendin-4. Culture of islets from non-diabetic cats at 25 mM glucose impaired secretion both in response to glucose and K+ depolarization. In conclusion, we describe a procedure for isolation of islets from cat pancreas biopsies and demonstrate that isolated cat islets secrete insulin in response to glucose and antidiabetic drugs. The study provides a basis for future ex vivo studies of islet function relevant to the understanding of the pathophysiology and treatment of feline diabetes.

Insulin Therapy Part 3: Cats

No insulin formulation should be considered best by default for management of feline diabetes. Rather, the choice of insulin formulation should be tailored to the specific clinical situation. In most cats that have some residual beta cell function, administering only a basal insulin might lead to complete normalization of blood glucose concentrations. Basal insulin requirements are constant throughout the day. Therefore, for an insulin formulation to be effective and safe as a basal insulin, its action should be roughly the same every hour of the day. At present, only insulin glargine U300 approaches this definition in cats.

Monitoring of Diabetes Mellitus Using the Flash Glucose Monitoring System: The Owners' Point of View

The flash glucose monitoring system (FGMS) has recently become one of the most common monitoring methods in dogs and cats with diabetes mellitus. The aim of this study was to evaluate the impact of FGMS on the quality of life of diabetic pet owners (DPOs). Fifty DPOs were asked to answer a 30-question survey. More than 80% of DPOs considered FGMS easier to use and less stressful and painful for the animal compared to blood glucose curves (BGCs). Overall, 92% of DPOs reported that their pet had better diabetes control since using FGMS. The most challenging aspects of using the FGMS were ensuring proper sensor fixation during the wearing period (47%), preventing premature detachment (40%), and purchasing the sensor (34%). Moreover, 36% of DPOs reported that the device cost was difficult to afford in the long term. Comparing dogs and cats, a significantly higher number of dogs' owners found the FGMS to be well-tolerated (79% vs. 40%), less invasive than BGCs (79% vs. 43%), and easier to maintain in situ (76% vs. 43%). In conclusion, FGMS is considered by DPOs to be easy to use and less stressful compared to BGCs, while enabling better glycemic control. Nevertheless, the costs related to its long-term use might be difficult to sustain.

Continuous Glucose Monitoring in Dogs and Cats: Application of New Technology to an Old Problem

In recent years, glucose monitoring has been revolutionized by the development of continuous glucose monitoring systems (CGMS), which are wearable non/minimally invasive devices that measure glucose concentration almost continuously for several consecutive d/wk. The Abbott FreeStyle Libre is the CGMS used most commonly. It has adequate clinical accuracy both in dogs and cats, even though the accuracy is lower in the hypoglycemic range. It allows an accurate identification of glycemic excursions occurring throughout the day as well as of glucose variations during consecutive days, enabling the clinician to make a more informed decision about the insulin dose and frequency of administration.

The Future of Diabetes Therapies: New Insulins and Insulin Delivery Systems, Glucagon-Like Peptide 1 Analogs, and Sodium-Glucose Cotransporter Type 2 Inhibitors, and Beta Cell Replacement Therapy

As the prevalence of diabetes mellitus increases, so too does the number of available treatment modalities. Many diabetic therapies available in human medicine or on the horizon could hold promise in the management of small animal diabetes. However, it is important to consider how species differences in pathophysiology, management practices and goals, and lifestyle may affect the translation of such treatment modalities for veterinary use. This review article aimed to familiarize veterinarians with the more promising novel diabetic therapies and explore their possible applications in the treatment of canine and feline diabetes mellitus.

Physiological and pharmacological actions of glucagon like peptide-1 (GLP-1) in domestic animals

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GLP-1 improves peripheral glucose uptake in healthy dogs and cats.

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GLP-1 analogues administration in diabetic cats reduces exogenous insulin requirement.

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Dogs cardiomyocytes apoptosis is reduced by GLP-1-derived molecules action.

Analogues of glucagon like peptide-1 (GLP-1) and other drugs that increase this peptide half-life are used worldwide in human medicine to treat type 2 diabetes mellitus (DM) and obesity. These molecules can increase insulin release and satiety, interesting effects that could also be useful in the treatment of domestic animals pathologies, however their use in veterinary medicine are still limited. Considering the increasing incidence of DM and obesity in cats and dogs, the aim of this review is to summarize the available information about the physiological and pharmacological actions of GLP-1 in domestic animals and discuss about its potential applications in veterinary medicine. In diabetic dogs, the use of drugs based on GLP-1 actions reduced blood glucose and increased glucose uptake, while in diabetic cats they reduced glycemic variability and exogenous insulin administration. Thus, available evidence indicates that GLP-1 based drugs could become alternatives to DM treatment in domestic animals. Nevertheless, current data do not provide enough elements to recommend these drugs widespread clinical use.

One hundred years of insulin: Is it time for smart?

Smarter understanding of diabetes pathophysiology and pharmacology of insulin therapy can lead to better clinical outcomes. Rather than looking for an insulin formulation that is considered "best" for a general population, it could be appropriate to seek the "smart" insulin choice, tailored to the specific clinical situation. Different treatment goals should be considered, with pros and cons to each. Ideally, insulin therapy in most diabetic dogs should mimic a "basal-bolus" pattern. The "intermediate"-acting insulin formulations might provide better "bolus" treatment in dogs than the rapid-acting formulations used in people. In patients with some residual beta cell function such as many diabetic cats, administering only a "basal" insulin might lead to complete normalisation of blood glucose concentrations. Insulin suspensions (neutral protamine Hagedorn, neutral protamine Hagedorn/regular mixes, lente and protamine zinc insulin) as well as insulin glargine U100 and detemir are "intermediate"-acting formulations that are administered twice daily. For a formulation to be an effective and safe "basal" insulin, its action should be roughly the same every hour of the day. Currently, only insulin glargine U300 and insulin degludec meet this standard in dogs, whereas in cats, insulin glargine U300 is the closest option.

Insulin glargine 300 U/ml for the treatment of feline diabetes mellitus

OBJECTIVES

The study aimed to evaluate the efficacy and safety of insulin glargine 300 U/ml (IGla-U300) in cats with variable duration of diabetes mellitus (DM).

METHODS

Thirteen client-owned cats with DM completed a prospective clinical trial. Four cats were highly suspected of hypersomatotropism and excluded from the insulin efficacy evaluation. All cats were treated with IGla-U300 SC at a starting dosage of 0.5 U/kg q12h and fed with a low carbohydrate diet. Cats were monitored for 8 weeks with a once-weekly at-home 16 h blood glucose curve (BGC) and a questionnaire evaluating the presence of DM-related clinical signs. In-clinic evaluations, including serum fructosamine measurement, were scheduled within 3 days of the first, third, sixth and eighth BGC. Glycemic variability was assessed by calculating the SD of each BGC.

RESULTS

Excluding four cats suspected of hypersomatotropism, at the time of the eighth BGC, improved or absent polyuria, polydipsia, polyphagia, weight loss, lethargy and improved or normal general demeanor were reported in 8/9 (88%), 8/9 (88%), 7/9 (77%), 7/9 (77%), 7/9 (77%) and 8/9 (88%) cats, respectively. Two cats achieved remission after 29 and 53 days. Another two cats went into remission after the end of the study (days 82 and 96). All cats that achieved remission were newly diagnosed diabetics. Median (range) serum fructosamine concentration significantly decreased when comparing the time of enrollment (604 [457-683] µmol/l) with the eighth week of treatment (366 [220-738] µmol/l) (P = 0.02). In all 13 cats, biochemical hypoglycemia (blood glucose <60 mg/dl; <3.3 mmol/l) was detected in 13/104 (12.5%) BGCs, while clinical signs suggesting hypoglycemic episodes were not reported. Glycemic variability was significantly lower at the fifth BGC when comparing cats that achieved remission with cats that did not achieve remission (P = 0.02).

CONCLUSIONS AND RELEVANCE

IGla-U300 seems effective and safe for the treatment of feline diabetes, but more long- term and comparative clinical trials are needed.

An ultra-long-acting recombinant insulin for the treatment of diabetes mellitus in cats

BACKGROUND

Treatment of diabetes mellitus (DM) in cats typically requires insulin injections q12h-q24h, posing a major compliance barrier for caregivers. Novel treatments enabling decreased injection frequency while maintaining safety are highly desirable. Insulin fused with feline immunoglobulin fragment crystallizable (Fc) has an ultra-long plasma half-life because it recycles through cells where it is protected from proteolysis.

HYPOTHESIS

Glycemic control can be achieved in diabetic cats with a recombinant fusion protein of a synthetic insulin and feline Fc (AKS-267c) administered SC weekly.

ANIMALS

Five cats with spontaneous DM.

METHODS

Cats previously controlled using insulin glargine q12h were transitioned to once-weekly injection of AKS-267c. The dose of AKS-267c was titrated weekly for 7 weeks based on continuous glucose monitoring. Clinical signs, body weight, fructosamine concentrations, and mean interstitial glucose concentrations (IG) were compared between baseline (week 0, on insulin glargine) and the last week of treatment. Data were assessed for normality and compared using parametric or nonparametric paired tests (as appropriate).

RESULTS

After 7 weeks of once-weekly injections, compared to baseline, there were no significant changes in clinical signs, body weight (median [range] gain, 0.1 kg [-0.1 to +0.7]; P = .5), fructosamine (-60 mmol/L [-338 to +206]; P = .6), and mean IG concentrations (change = -153 mmol/L [-179 to +29]; P = .3), and no adverse reactions were reported.

CONCLUSION

Successful control of clinical signs and maintenance of glycemia was achieved with this once-weekly novel insulin treatment. The efficacy and safety of this novel formulation should be further assessed in a large clinical trial.

Glycemic variability in newly diagnosed diabetic cats treated with the glucagon-like peptide-1 analogue exenatide extended release

Background

Glycemic variability (GV) is an indicator of glycemic control and can be evaluated by calculating the SD of blood glucose measurements. In humans with diabetes mellitus (DM), adding a glucagon‐like peptide‐1 (GLP‐1) analogue to conventional therapy reduces GV. In diabetic cats, the influence of GLP‐1 analogues on GV is unknown.

Objective

To evaluate GV in diabetic cats receiving the GLP‐1 analogue exenatide extended release (EER) and insulin.

Animals

Thirty client‐owned cats with newly diagnosed spontaneous DM.

Methods

Retrospective study. Blood glucose curves from a recent prospective placebo‐controlled clinical trial generated 1, 3, 6, 10, and 16 weeks after starting therapy were retrospectively evaluated for GV. Cats received either EER (200 μg/kg) or 0.9% saline SC once weekly, insulin glargine and a low‐carbohydrate diet. Mean blood glucose concentrations were calculated and GV was assessed by SD. Data were analyzed using nonparametric tests.

Results

In the EER group, GV (mean SD [95% confidence interval]) was lower at weeks 6 (1.69 mmol/L [0.9‐2.48]; P = .02), 10 (1.14 mmol/L [0.66‐1.62]; P = .002) and 16 (1.66 mmol/L [1.09‐2.23]; P = .02) compared to week 1 (4.21 mmol/L [2.48‐5.93]) and lower compared to placebo at week 6 (3.29 mmol/L [1.95‐4.63]; P = .04) and week 10 (4.34 mmol/L [2.43‐6.24]; P < .000). Cats achieving remission (1.21 mmol/L [0.23‐2.19]) had lower GV compared to those without remission (2.96 mmol/L [1.97‐3.96]; P = .01) at week 6.

Conclusions and Clinical Importance

The combination of EER, insulin, and a low‐carbohydrate diet might be advantageous in the treatment of newly diagnosed diabetic cats.