Thiazolidinediones and fracture risk in patients with Type 2 diabetes

Cladosporols and PPARγ: Same Gun, Same Bullet, More Targets

Several natural compounds have been found to act as PPARγ agonists, thus regulating numerous biological processes, including the metabolism of carbohydrates and lipids, cell proliferation and differentiation, angiogenesis, and inflammation. Recently, Cladosporols, secondary metabolites purified from the fungus Cladosporium tenuissimum, have been demonstrated to display an efficient ability to control cell proliferation in human colorectal and prostate cancer cells through a PPARγ-mediated modulation of gene expression. In addition, Cladosporols exhibited a strong anti-adipogenetic activity in 3T3-L1 murine preadipocytes, preventing their in vitro differentiation into mature adipocytes. These data interestingly point out that the interaction between Cladosporols and PPARγ, in the milieu of different cells or tissues, might generate a wide range of beneficial effects for the entire organism affected by diabetes, obesity, inflammation, and cancer. This review explores the molecular mechanisms by which the Cladosporol/PPARγ complex may simultaneously interfere with a dysregulated lipid metabolism and cancer promotion and progression, highlighting the potential therapeutic benefits of Cladosporols for human health.

Glucagon-like Peptide-1 Receptor Agonists and Diabetic Osteopathy: Another Positive Effect of Incretines? A 12 Months Longitudinal Study

Diabetic osteopathy is a frequent complication in patients with type 2 diabetes mellitus (T2DM). The association between T2DM and increased fracture risk has led to study the impact of new antidiabetic drugs on bone metabolism. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are incretin mimetic drugs which have many pleiotropic properties. The relationship between GLP-1RAs and bone is very complex: while in vitro and animal studies have demonstrated a protective effect on bone, human studies are scarce. We led a 12 months longitudinal study evaluating bone changes in 65 patients withT2DM for whom a therapy with GLP-1RAs had been planned. Fifty-four T2DM patients completed the 12-month study period; of them, 30 had been treated with weekly dulaglutide and 24 with weekly semaglutide. One-year therapy with GLP-1RAs resulted in a significant reduction in weight and BMI. Bone mineral density (BMD), bone metabolism, trabecular bone score (TBS), adiponectin, and myostatin were evaluated before and after 12 months of GLP-1RAs therapy. After 12 months of therapy bone turnover markers and adiponectin showed a significant increase, while myostatin values showed a modest but significant reduction. BMD-LS by DXA presented a significant reduction while the reduction in BMD-LS by REMS was not significant and TBS values showed a marginal increase. Both DXA and REMS techniques showed a modest but significant reduction in femoral BMD. In conclusion, the use of GLP-1RAs for 12 months preserves bone quality and reactivates bone turnover. Further studies are needed to confirm whether GLP-1RAs could represent a useful therapeutic option for patients with T2DM and osteoporosis.

Indirect comparison of efficacy and safety of chiglitazar and thiazolidinedione in patients with type 2 diabetes: A meta-analysis

BACKGROUND

Chiglitazar is an emerging pan-agonist of all peroxisome proliferator activated receptors (PPAR)-α, δ and γ, and has therapeutic potential for type 2 diabetes (T2D). However, to date, no clinical studies or meta-analyses have compared the efficacy and safety of chiglitazar and traditional PPAR-γ agonist thiazolidinediones (TZDs). A meta-analysis concerning this topic is therefore required.

AIM

To compare the efficacy and safety of chiglitazar and TZD in patients with T2D.

METHODS

PubMed, Medline, Embase, the Cochrane Central Register of Controlled Trials, Reference Citation Analysis and Clinicaltrial.gov websites were searched from August 1994 to March 2022. Randomized controlled trials (RCTs) of chiglitazar or TZD vs placebo in patients with T2D were included. Indirect comparisons and sensitivity analyses were implemented to evaluate multiple efficacy and safety endpoints of interest.

RESULTS

We included 93 RCTs that compared TZD with placebo and one that compared chiglitazar with placebo. For efficacy endpoints, the augmented dose of chig-litazar resulted in greater reductions in hemoglobin (Hb)A1c [weighted mean difference (WMD) = -0.15%, 95% confidence interval (CI): -0.27 to -0.04%], triglycerides (WMD = -0.17 mmol/L, 95%CI: -0.24 to -0.11 mmol/L) and alanine aminotransferase (WMD = -5.25 U/L, 95%CI: -8.50 to -1.99 U/L), and a greater increase in homeostasis model assessment-β (HOMA-β) (WMD = 17.75, 95%CI: 10.73-24.77) when compared with TZD treatment. For safety endpoints, the risks of hypoglycemia, edema, bone fractures, upper respiratory tract infection, urinary tract infection, and weight gain were all comparable between the augmented dose of chiglitazar and TZD. In patients with baseline HbA1c ≥ 8.5%, body mass index ≥ 30 kg/m2 or diabetes duration < 10 years, the HbA1c reduction and HOMA-β increase were more conspicuous for the augmented dose of chiglitazar compared with TZD.

CONCLUSION

Augmented dose of chiglitazar, a pan-activator of PPARs, may serve as an antidiabetic agent with preferable glycemic and lipid control, better β-cell function preserving capacity, and does not increase the risk of safety concerns when compared with TZD.

2022 update to the position statement by Primary Care Diabetes Europe: a disease state approach to the pharmacological management of type 2 diabetes in primary care

Type 2 diabetes and its associated comorbidities are growing more prevalent, and the complexity of optimising glycaemic control is increasing, especially on the frontlines of patient care. In many countries, most patients with type 2 diabetes are managed in a primary care setting. However, primary healthcare professionals face the challenge of the growing plethora of available treatment options for managing hyperglycaemia, leading to difficultly in making treatment decisions and contributing to treatment and therapeutic inertia. This position statement offers a simple and patient-centred clinical decision-making model with practical treatment recommendations that can be widely implemented by primary care clinicians worldwide through shared-decision conversations with their patients. It highlights the importance of managing cardiovascular disease and elevated cardiovascular risk in people with type 2 diabetes and aims to provide innovative risk stratification and treatment strategies that connect patients with the most effective care.

5-Benzylidene, 5-benzyl, and 3-benzylthiazolidine-2,4-diones as potential inhibitors of the mitochondrial pyruvate carrier: Effects on mitochondrial functions and survival in Drosophila melanogaster

A series of thiazolidinediones (TZDs) were synthesized and screened for their effect on the mitochondrial respiration as well as on several mitochondrial respiratory system components of Drosophila melanogaster. Substituted and non-substituted 5-benzylidene and 5-benzylthiazolidine-2,4-diones were investigated. The effect of a substitution in position 3, at the nitrogen atom, of the thiozolidine heterocycle was also investigated. The designed TZDs were compared to UK5099, the most potent mitochondrial pyruvate carrier (MPC) inhibitor, in in vitro and in vivo tests. Compared to 5-benzylthiazolidine-2,4-diones 6-7 and 3-benzylthiazolidine-2,4-dione 8, 5-benzylidenethiazolidine-2,4-diones 2-5 showed more inhibitory capacity on mitochondrial respiration. 5-(4-Hydroxybenzylidene)thiazolidine-2,4-dione (3) and 5-(3-hydroxy-4-methoxybenzylidene)thiazolidine-2,4-dione (5) were among the best compounds that compared well with UK5099. Additionally, TZDs 3 and 5, showed no effects on the non-coupled respiration and weak effects on pathways using substrates such as proline, succinate, and G3P. 5-Benzylidenethiazolidine-2,4-dione 3 showed a positive effect on survival and lifespan when added to Drosophila standard and high fat diet. Interestingly, analog 3 completely reversed the effects of high fat diet on Drosophila longevity and induced metabolic changes which suggests an in vivo inhibition of MPC at the mitochondrial level.

An overview of alogliptin + pioglitazone for the treatment of type 2 diabetes

INTRODUCTION

Type 2 diabetes (T2D) is a progressive condition, and sequential additions of therapy are usually required to maintain glycemic control. The options for glucose lowering therapies have increased considerably in recent years. Fixed-dose combinations such as alogliptin with pioglitazone provide a convenient choice which can improve medication adherence.

AREAS COVERED

The authors performed a literature search to identify publications describing the efficacy and safety of alogliptin and pioglitazone when used separately and in combinations.

EXPERT OPINION

Pioglitazone activates peroxisome proliferator-activated receptor-gamma which improves insulin sensitivity and helps to preserve β-cell function with a durable improvement in glycemic control. Pioglitazone can retard the progression of atherosclerosis and reduce cardiovascular events, but it is associated with adverse events including weight gain, fluid retention, and increased risk of fractures. Alogliptin improves glycemic control and appears neutral in terms of cardiovascular events. It does not appear to increase the adverse events associated with pioglitazone and use of the combination may permit the use of lower doses of pioglitazone with reduced adverse effects. There are no cardiovascular outcome studies with the combination but the cardiovascular benefits of pioglitazone and additional glucose lowering effects of alogliptin provide a useful combination with convenient once daily dosing.

Bone fragility in patients with diabetes mellitus: A consensus statement from the working group of the Italian Diabetes Society (SID), Italian Society of Endocrinology (SIE), Italian Society of Gerontology and Geriatrics (SIGG), Italian Society of Orthopaedics and Traumatology (SIOT)

Bone fragility is one of the possible complications of diabetes, either type 1 (T1D) or type 2 (T2D). Bone fragility can affect patients of different age and with different disease severity depending on type of diabetes, disease duration and the presence of other complications. Fracture risk assessment should be started at different stages in the natural history of the disease depending on the type of diabetes and other risk factors. The risk of fracture in T1D is higher than in T2D, imposing a much earlier screening and therapeutic intervention that should also take into account a patient's life expectancy, diabetes complications etc. The therapeutic armamentarium for T2D has been enriched with drugs that may influence bone metabolism, and clinicians should be aware of these effects. Considering the complexity of diabetes and osteoporosis and the range of variables that influence treatment choices in a given individual, the Working Group on bone fragility in patients with diabetes mellitus has identified and issued recommendations based on the variables that should guide screening of bone fragility and management of diabetes and bone fragility: (A)ge, (B)MD, (C)omplications, (D)uration of disease, & (F)ractures (ABCD&F). Consideration of these parameters may help clinicians identify the best time for screening, the appropriate glycaemic target and anti-osteoporosis drug for patients with diabetes at risk of or with bone fragility.

Ligand and structure-based computational designing of multi-target molecules directing FFAR-1, FFAR-4 and PPAR-G as modulators of insulin receptor activity

Multi-agent therapies are an important treatment modality in many diseases based on the assumption that combining agents may result in increased therapeutic benefit by overcoming the mechanism of resistance and providing superior efficiency. Extensively validated 3D pharmacophore models for free fatty acid receptor-1 (FFAR-1), free fatty acid receptor-4 (FFAR-4), and peroxisome proliferator-activated receptor-G (PPAR-G) was developed. The pharmacophore model for FFAR-1 (r² = 0.98, q² = 0.90) and PPAR-G (r² = 0.89, q² = 0.88) suggested that one hydrogen bond acceptor, one hydrogen bond donor, three aromatic rings, and two hydrophobic groups arranged in 3D space are essential for the binding affinity of FFAR-1 and PPAR-G inhibitors. Similarly, the pharmacophore model for FFAR-4 (r² = 0.92, q² = 0.87) suggested that the presence of a hydrogen bond acceptor, one negative atom, two aromatic rings, and three hydrophobic groups plays a vital role in the binding of an inhibitor of FFAR-4. These pharmacophore models allowed searches for novel FFAR-1, PPAR-G, and FFAR-4 triple inhibitors from multi-conformer 3D databases (Asinex). Finally, the twenty-five best hits were selected for molecular docking, to study the interaction of their complexes with all the proteins and final binding orientations of these molecules. After molecular docking, ten hits have been predicted to possess good binding affinity as per the Molecular Mechanics Generalized Born Surface Area (MM-GBSA) calculation for FFAR-1, FFAR-4, and PPAR-G which can be further investigated for its experimental in-vitro/in-vivo anti-diabetic activities.Communicated by Ramaswamy H. Sarma.

A disease state approach to the pharmacological management of Type 2 diabetes in primary care: A position statement by Primary Care Diabetes Europe

Type 2 diabetes and its associated comorbidities are growing more prevalent, and the complexity of optimising glycaemic control is increasing, especially on the frontlines of patient care. In many countries, most patients with type 2 diabetes are managed in a primary care setting. However, primary healthcare professionals face the challenge of the growing plethora of available treatment options for managing hyperglycaemia, leading to difficultly in making treatment decisions and contributing to therapeutic inertia. This position statement offers a simple and patient-centred clinical decision-making model with practical treatment recommendations that can be widely implemented by primary care clinicians worldwide through shared-decision conversations with their patients. It highlights the importance of managing cardiovascular disease and elevated cardiovascular risk in people with type 2 diabetes and aims to provide innovative risk stratification and treatment strategies that connect patients with the most effective care.

Herbal Decoction Divya-Peedantak-Kwath Alleviates Allodynia and Hyperalgesia in Mice Model of Chemotherapy-Induced Peripheral Neuropathy via Modulation in Cytokine Response

The widely used cancer treatment, chemotherapy, causes severe long-term neuropathic pain in 30–40% cases, the condition clinically known as chemotherapy-induced peripheral neuropathy (CIPN). Approved conventional analgesics are sometimes ineffective, while others like opioids have undesirable side effects like addiction, seizures, and respiratory malfunctioning. Tricyclic antidepressants and anticonvulsants, although exhibit anti-allodynic effects in neuropathy, also have unpleasant side effects. Thus, alternative medicines are being explored for CIPN treatment. Despite scattered reports on different extracts from different plants having potential anti-allodynic effects against CIPN, no established medicine or formulation of herbal origin exists. In this study, efficacy of an herbal decoction, formulated based on ancient medicinal principles and protocols for treating neuropathic pain, Divya-Peedantak-Kwath (DPK), has been evaluated in a paclitaxel (PTX)-induced peripheral neuropathic mouse model. We observed that DPK has prominent anti-allodynic and anti-hyperalgesic effects and acts as a nociceptive modulator for CIPN. With exhibited antioxidative effects, DPK restored the redox potential of the sciatic nerves to the normal. On histopathological evaluation, DPK prevented the PTX-induced lesions in the sciatic nerve, in a dose-dependent manner. It also prevented inflammation by modulating the levels of pro-inflammatory cytokines involved in CIPN pathogenesis. Our observations evinced that DPK can alleviate CIPN by attenuating oxidative stress and concomitant neuroinflammation through immune modulation.

Adipose tissue in health and disease

Adipose, or fat, tissue (AT) was once considered an inert tissue that primarily existed to store lipids, and was not historically recognized as an important organ in the regulation and maintenance of health. With the rise of obesity and more rigorous research, AT is now recognized as a highly complex metabolic organ involved in a host of important physiological functions, including glucose homeostasis and a multitude of endocrine capabilities. AT dysfunction has been implicated in several disease states, most notably obesity, metabolic syndrome and type 2 diabetes. The study of AT has provided useful insight in developing strategies to combat these highly prevalent metabolic diseases. This review highlights the major functions of adipose tissue and the consequences that can occur when disruption of these functions leads to systemic metabolic dysfunction.

A prospective pilot study of the effect of acupuncture on insulin sensitivity in women with polycystic ovary syndrome and insulin resistance

OBJECTIVE

To test the hypothesis that acupuncture improves insulin sensitivity in women with polycystic ovary syndrome (PCOS) and insulin resistance (IR).

DESIGN

Prospective pilot study.

SETTING

Guangzhou, China, 2014-2016.

PARTICIPANTS

Eighty women with PCOS aged 18-40 years with body mass index (BMI) above 18.5 kg/m² and with homeostatic model assessment for insulin resistance (HOMA-IR) index ⩾2.14.

INTERVENTIONS

Subjects received acupuncture with combined manual and low-frequency electrical stimulation of the needles three times per week for 6 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the change in HOMA-IR after 6 months of acupuncture relative to baseline. Secondary outcomes included changes after 6 months of acupuncture and at 3 months of follow-up (both relative to baseline) in oral glucose tolerance test (OGTT) parameters (glucose and insulin levels), anthropometric measurements, and circulating metabolic and endocrine variables.

RESULTS

HOMA-IR and fasting plasma glucose and insulin levels were significantly decreased after 6 months of acupuncture, and both HOMA-IR and fasting insulin remained significantly decreased at 3 months of follow-up. In a subgroup analysis of normal-weight and overweight/obese women, HOMA-IR was reduced after 6 months of acupuncture in both subgroups, but there was no significant difference between the two groups.

CONCLUSIONS

Acupuncture treatment in Chinese women with PCOS and IR was associated with an encouraging improvement in insulin sensitivity. Further randomized controlled studies are required to confirm the efficacy of acupuncture for this indication.

Pioglitazone: The forgotten, cost-effective cardioprotective drug for type 2 diabetes

Type 2 diabetes individuals are at high risk for macrovascular complications: myocardial infarction, stroke and cardiovascular mortality. Recent cardiovascular outcome trials have demonstrated that agents in two antidiabetic classes (SGLT2 inhibitors and GLP-1 receptor agonists) reduce major adverse cardiovascular events. However, there is strong evidence that an older and now generically available medication, the thiazolidinedione, pioglitazone, can retard the atherosclerotic process (PERISCOPE and Chicago) and reduce cardiovascular events in large randomized prospective cardiovascular outcome trials (IRIS and PROactive). Pioglitazone is a potent insulin sensitizer, preserves beta-cell function, causes durable reduction in HbA1c, corrects multiple components of metabolic syndrome and improves nonalcoholic fatty liver disease/nonalcoholic steatohepatitis. Adverse effects (weight gain, fluid retention, fractures) must be considered, but are diminished with lower doses and are arguably outweighed by these multiple benefits. With healthcare expenses attributable to diabetes increasing rapidly, this cost-effective drug requires reconsideration in the therapeutic armamentarium for the disease.

Diabetes pharmacotherapy and effects on the musculoskeletal system

Persons with type 1 or type 2 diabetes have a significantly higher fracture risk than age-matched persons without diabetes, attributed to disease-specific deficits in the microarchitecture and material properties of bone tissue. Therefore, independent effects of diabetes drugs on skeletal integrity are vitally important. Studies of incretin-based therapies have shown divergent effects of different agents on fracture risk, including detrimental, beneficial, and neutral effects. The sulfonylurea class of drugs, owing to its hypoglycemic potential, is thought to amplify the risk of fall-related fractures, particularly in the elderly. Other agents such as the biguanides may, in fact, be osteo-anabolic. In contrast, despite similarly expected anabolic properties of insulin, data suggests that insulin pharmacotherapy itself, particularly in type 2 diabetes, may be a risk factor for fracture, negatively associated with determinants of bone quality and bone strength. Finally, sodium-dependent glucose co-transporter 2 inhibitors have been associated with an increased risk of atypical fractures in select populations, and possibly with an increase in lower extremity amputation with specific SGLT2I drugs. The role of skeletal muscle, as a potential mediator and determinant of bone quality, is also a relevant area of exploration. Currently, data regarding the impact of glucose lowering medications on diabetes-related muscle atrophy is more limited, although preclinical studies suggest that various hypoglycemic agents may have either aggravating (sulfonylureas, glinides) or repairing (thiazolidinediones, biguanides, incretins) effects on skeletal muscle atrophy, thereby influencing bone quality. Hence, the therapeutic efficacy of each hypoglycemic agent must also be evaluated in light of its impact, alone or in combination, on musculoskeletal health, when determining an individualized treatment approach. Moreover, the effect of newer medications (potentially seeking expanded clinical indication into the pediatric age range) on the growing skeleton is largely unknown. Herein, we review the available literature regarding effects of diabetes pharmacotherapy, by drug class and/or by clinical indication, on the musculoskeletal health of persons with diabetes.

Bronchopulmonary Dysplasia: Crosstalk Between PPARγ, WNT/β-Catenin and TGF-β Pathways; The Potential Therapeutic Role of PPARγ Agonists

Bronchopulmonary dysplasia (BPD) is a serious pulmonary disease which occurs in preterm infants. Mortality remains high due to a lack of effective treatment, despite significant progress in neonatal resuscitation. In BPD, a persistently high level of canonical WNT/β-catenin pathway activity at the canalicular stage disturbs the pulmonary maturation at the saccular and alveolar stages. The excessive thickness of the alveolar wall impairs the normal diffusion of oxygen and carbon dioxide, leading to hypoxia. Transforming growth factor (TGF-β) up-regulates canonical WNT signaling and inhibits the peroxysome proliferator activated receptor gamma (PPARγ). This profile is observed in BPD, especially in animal models. Following a premature birth, hypoxia activates the canonical WNT/TGF-β axis at the expense of PPARγ. This gives rise to the differentiation of fibroblasts into myofibroblasts, which can lead to pulmonary fibrosis that impairs the respiratory function after birth, during childhood and even adulthood. Potential therapeutic treatment could target the inhibition of the canonical WNT/TGF-β pathway and the stimulation of PPARγ activity, in particular by the administration of nebulized PPARγ agonists.

DPP-4 inhibitor impedes lipopolysaccharide-induced osteoclast formation and bone resorption in vivo

OBJECTIVES

Dipeptidyl peptidase 4 (DPP-4) inhibition is a new therapeutic strategy for type 2 diabetic patients. DPP-4 has been reported to enhance inflammation. However, the effect of DPP-4 inhibition on inflammation remains unknown. Lipopolysaccharide (LPS) is a strong inducer of inflammation and osteoclast formation. In this study, we investigated in vivo effects of DPP-4 inhibition on LPS-induced osteoclast formation and bone resorption, as well as in vitro effects of DPP-4 inhibition on RANKL-induced osteoclastogenesis and TNF-α-induced osteoclastogenesis.

METHODS

LPS with or without a DPP-4 inhibitor was subcutaneously injected into mouse calvaria for 5 days. Histological sections of calvaria were stained for tartrate-resistant acid phosphatase, and osteoclast numbers were determined. The ratio of calvaria bone resorption was evaluated via microfocal computed tomography reconstruction images.

RESULTS

Osteoclast number and bone resorption were significantly lower in mice that underwent LPS and DPP-4 inhibitor co-administration than in those that underwent LPS administration alone. Moreover, RANKL, TNF-α, and M-CSF expression was reduced in the LPS and DPP-4 inhibitor co-administration group. In vitro, there were no direct effects of DPP-4 inhibitor or DPP-4 on RANKL- and TNF-α-induced osteoclastogenesis, or on LPS-induced RANKL expression in stromal cells. Nevertheless, macrophages from LPS and DPP-4 inhibitor co-administered mice exhibited lower TNF-α expression than macrophages from LPS-only mice. Notably, TNF-α expression was not reduced in LPS and DPP-4 inhibitor co-treated macrophages in vitro, compared with macrophages treated with LPS alone.

Dipeptidyl peptidase-4 inhibitor use is associated with decreased risk of fracture in patients with type 2 diabetes: a population-based cohort study

AIMS

The aim of this study was to investigate the putative link between dipeptidyl peptidase-4 inhibitor (DPP-4i) use and the risk of fracture in patients with type 2 diabetes.

METHODS

This propensity-score-matched population-based cohort study was performed between 2009 and 2013 on patients with type 2 diabetes who were stable metformin users. A total of 3996 patients with type 2 diabetes used DPP-4i as a second-line antidiabetic drug. The same number of matched non-DPP-4i users were followed up until fracture occurrence, health insurance policy termination, or the end of 2013. The incidence rates of overall and cause-specific fractures were estimated based on the Poisson assumption. A multiple Cox proportional hazard model was used to estimate the covariate-adjusted hazard ratio (HR) and 95% confidence interval (CI) to determine the association between DPP-4i use and overall and cause-specific fractures stratified by age and sex.

RESULTS

Over a maximum follow-up period of 5 years, 340 DPP-4i users and 419 non-DPP-4i users were newly diagnosed with fractures, yielding incidence rates of 28.03 and 32.04 per 1000 people per year, respectively. The Cox proportional hazard model revealed that DPP-4i use significantly reduced the risk of all-cause fractures and upper extremity fractures, with adjusted HRs of 0.86 (95% CI: 0.74-0.99) and 0.75 (95% CI: 0.59-0.95), respectively. The aforementioned associations of DDP-4i use with fracture were sustained across sex and age stratifications.

CONCLUSIONS

The results of this study supported the premise that DPP-4i usage is associated with a reduced risk of all-cause fractures and upper extremity fractures in patients with type 2 diabetes.

The Glucagon-Like Peptide-1 Receptor Agonist Exendin-4 Inhibits Lipopolysaccharide-Induced Osteoclast Formation and Bone Resorption via Inhibition of TNF-α Expression in Macrophages

Glucagon-like peptide-1 (GLP-1) receptor agonists are an effective treatment approach for type 2 diabetes. Recently, anti-inflammatory effects of GLP-1 receptor agonists have also been reported. Lipopolysaccharide (LPS) induces inflammation and osteoclast formation. In this study, we investigated the effect of exendin-4, a widely used GLP-1 receptor agonist, in LPS-induced osteoclast formation and bone resorption. LPS with or without exendin-4 was administered on mouse calvariae by daily subcutaneous injection. The number of osteoclasts, the ratio of bone resorption pits, and the level of C-terminal cross-linked telopeptide of type I collagen (CTX) were significantly lower in LPS- and exendin-4-coadministered mice than in mice administered with LPS alone. RANKL and TNF-α mRNA expression levels were lower in the exendin-4- and LPS-coadministered group than in the LPS-administered group. Our in vitro results showed no direct effects of exendin-4 on RANKL-induced osteoclast formation, TNF-α-induced osteoclast formation, or LPS-induced RANKL expression in stromal cells. Conversely, TNF-α mRNA expression was inhibited in the exendin-4- and LPS-cotreated macrophages compared with cells treated with LPS alone. These results indicate that the GLP-1 receptor agonist exendin-4 may inhibit LPS-induced osteoclast formation and bone resorption by inhibiting LPS-induced TNF-α production in macrophages.

PPARs: Key Regulators of Airway Inflammation and Potential Therapeutic Targets in Asthma

Asthma affects approximately 300 million people worldwide, significantly impacting quality of life and healthcare costs. While current therapies are effective in controlling many patients' symptoms, a large number continue to experience exacerbations or treatment-related adverse effects. Alternative therapies are thus urgently needed. Accumulating evidence has shown that the peroxisome proliferator-activated receptor (PPAR) family of nuclear hormone receptors, comprising PPARα, PPARβ/δ, and PPARγ, is involved in asthma pathogenesis and that ligand-induced activation of these receptors suppresses asthma pathology. PPAR agonists exert their anti-inflammatory effects primarily by suppressing pro-inflammatory mediators and antagonizing the pro-inflammatory functions of various cell types relevant to asthma pathophysiology. Experimental findings strongly support the potential clinical benefits of PPAR agonists in the treatment of asthma. We review current literature, highlighting PPARs' key role in asthma pathogenesis and their agonists' therapeutic potential. With additional research and rigorous clinical studies, PPARs may become attractive therapeutic targets in this disease.

Weak bones in diabetes mellitus – an update on pharmaceutical treatment options

Objectives

Diabetes mellitus is often associated with a number of complications such as nephropathy, neuropathy, retinopathy and foot ulcers. However, weak bone is a diabetic complication that is often overlooked. Although the exact mechanism for weak bones within diabetes mellitus is unclear, studies have shown that the mechanism does differ in both type I (T1DM) and type II diabetes (T2DM). This review, however, investigates the application of mesenchymal stem cells, recombinant human bone morphogenetic protein-2, teriparatide, insulin administration and the effectiveness of a peroxisome proliferator-activated receptor-ϒ modulator, netoglitazone in the context of diabetic weak bones.

Key findings

In T1DM, weak bones may be the result of defective osteoblast activity, the absence of insulin's anabolic effects on bone, the deregulation of the bone–pancreas negative feedback loop and advanced glycation end product (AGE) aggregation within the bone matrix as a result of hyperglycaemia. Interestingly, T2DM patients placed on insulin administration, thiazolidinediones, SGLT2 inhibitors and sulfonylureas have an associated increased fracture risk. T2DM patients are also observed to have high sclerostin levels that impair osteoblast gene transcription, AGE aggregation within bone, which compromises bone strength and a decrease in esRAGE concentration resulting in a negative association with vertebral fractures.

Summary

Effective treatment options for weak bones in the context of diabetes are currently lacking. There is certainly scope for discovery and development of novel agents that could alleviate this complication in diabetes patients.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

Acupuncture treatment for insulin sensitivity of women with polycystic ovary syndrome and insulin resistance: a study protocol for a randomized controlled trial

BACKGROUND

Our prospective pilot study of acupuncture affecting insulin sensitivity on polycystic ovary syndrome (PCOS) combined with insulin resistance (IR) showed that acupuncture had a significant effect on improving the insulin sensitivity of PCOS. But there is still no randomized controlled trial to determine the effect of acupuncture on the insulin sensitivity in women with PCOS and IR. In this article, we present the protocol of a randomized controlled trial to compare the effect of true acupuncture on the insulin sensitivity of these patients compared with metformin and sham acupuncture. Acupuncture may be an effective therapeutic alternative that is superior to metformin and sham acupuncture in improving the insulin sensitivity of PCOS combined with IR.

METHODS

This study is a multi-center, controlled, double-blind, and randomized clinical trial aiming to evaluate the effect of acupuncture on the insulin sensitivity in PCOS combined with IR. In total 342 patients diagnosed with PCOS and IR will be enrolled. Participants will be randomized to one of the three groups: (1) true acupuncture + metformin placebo; (2) sham acupuncture + metformin, and (3) sham acupuncture + metformin placebo. Participants and assessors will be blinded. The acupuncture intervention will be given 3 days per week for a total of 48 treatment sessions during 4 months. Metformin (0.5 g per pill) or placebo will be given, three times per day, and for 4 months. Primary outcome measures are changes in homeostasis model assessment of insulin resistance (HOMA-IR) and improvement rate of HOMA-IR by oral glucose tolerance test (OGTT) and insulin releasing test (Ins). Secondary outcome measures are homeostasis model assessment-β (HOMA-β), area under the curve for glucose and insulin, frequency of regular menstrual cycles and ovulation, body composition, metabolic profile, hormonal profile, questionnaires, side effect profile, and expectation and credibility of treatment. Outcome measures are collected at baseline, at the end of treatments, and 3 months after the last acupuncture treatment. On completion of the screening visit, randomization will be conducted using a central randomization system.

DISCUSSION

This study will investigate the effects of acupuncture on the insulin sensitivity of PCOS and IR women compared with metformin and sham acupuncture. We will test whether true acupuncture with needles placed in skeletal muscles and stimulated manually and by electrical stimulation is more effective than metformin and sham acupuncture with superficial needle placement with no manual or electrical stimulation in improving the insulin sensitivity in PCOS women with IR.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02491333 ; Chinese Clinical Trial Registry, ChiCTR-ICR-15006639. Registered on 24 June 2015.

Revitalization of pioglitazone: the optimum agent to be combined with a sodium-glucose co-transporter-2 inhibitor

The recently completed EMPA-REG study showed that empagliflozin significantly decreased the major adverse cardiac events (MACE) endpoint, which comprised cardiovascular death, non-fatal myocardial infarction (MI) and stroke, in patients with high-risk type 2 diabetes (T2DM), primarily through a reduction in cardiovascular death, without a significant decrease in either MI or stroke. In the PROactive study, pioglitazone decreased the MACE endpoint by a similar degree to that observed in the EMPA-REG study, through a marked reduction in both recurrent MI and stroke and a modest reduction in cardiovascular death. These observations suggest that pioglitazone might be an ideal agent to combine with empagliflozin to further reduce cardiovascular events in patients with high-risk diabetes as empagliflozin also promotes salt/water loss and would be expected to offset any fluid retention associated with pioglitazone therapy. In the present paper, we provide an overview of the potential benefits of combined pioglitazone/empagliflozin therapy to prevent cardiovascular events in patients with T2DM.

Sulfonylurea use and risk of hip fractures among elderly men and women with type 2 diabetes

BACKGROUND

Both increased age and type 2 diabetes mellitus are risk factors for developing bone fractures. While recent data in the elderly suggest a link between hypoglycemia and fall-related fractures, the association between sulfonylureas, commonly used hypoglycemic agents, and fracture risk has not been well investigated.

METHODS

We used patient data from a large commercial health insurer from 2002-2005. Individuals aged ≥65 years receiving oral sulfonylurea treatment (n=13,195) were matched 1:1 to non-users based on propensity for sulfonylurea use. Multivariable conditional logistic regression was used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CIs).

RESULTS

During an average 4 years of follow-up, sulfonylurea users experienced 226 incident hip fractures (1.7%) and non-users experienced 157 (1.2%). Sulfonylurea use was associated with increased risk of developing hip fracture (aOR 1.46, 95% CI 1.17-1.82), and this association was apparent for men (120 cases; aOR 1.83, 95% CI 1.25-2.66) and women (263 cases; aOR 1.32, 95% CI 1.03-1.69). Patients with documented hypoglycemia in the follow-up period had increased odds of hip fracture relative to those without such diagnosis (aOR 2.42, 95% CI 1.35-4.34).

CONCLUSION

Sulfonylureas are associated with increased risk of hip fracture in elderly men and women with type 2 diabetes.

Beneficial metabolic actions of a stable GIP agonist following pre-treatment with a SGLT2 inhibitor in high fat fed diabetic mice

The purpose of the present study was to examine if a stable glucose-dependent insulinotropic polypeptide (GIP) agonist could exert beneficial metabolic control in diabetic mice which had been pre-treated with sodium-glucose-cotransporter-2 (SGLT2) inhibitor dapagliflozin (DAPA). High fat fed mice administered low dose streptozotocin (STZ) received vehicle, DAPA once-daily over 28 days, or DAPA once-daily for 14 days followed by (DAla(2))GIP once-daily for 14 days. Energy intake, body weight, glucose and insulin concentrations were measured at regular intervals. Glucose tolerance, insulin tolerance test, dual-energy X-ray absorptiometry (DEXA) and pancreatic histology were examined. Once-daily administration of (DAla(2))GIP for 14 days in high fat fed diabetic mice pre-treated with DAPA demonstrated significant decrease in body weight, blood glucose and increased insulin concentrations which were independent of changes in energy intake. Similarly, glucose tolerance, glucose-stimulated insulin secretion, insulin sensitivity and HOMA-β were significantly enhanced in (DAla(2))GIP-treated mice. DEXA analysis revealed sustained percentage body fat loss with no changes in lean mass, bone mineral content and density. Pancreatic immunohistochemical analysis revealed decreased islet number and increases in islet area, beta cell area and pancreatic insulin content. The DAPA-induced increase in alpha cell area was also reversed. Additional acute in vitro and in vivo experiments confirmed that the impaired action of (DAla(2))GIP under hyperglycaemic-induced conditions was significantly reversed by DAPA treatment. These data demonstrate that (DAla(2))GIP can exert beneficial metabolic control in high fat fed diabetic mice pre-treated with DAPA. The results highlight possibility of a targeted and personalized approach using a GIP agonist and SGLT2 inhibitor for the treatment of type 2 diabetes.

Diabetes and bone: biological and environmental factors

PURPOSE OF REVIEW

Type 1 and type 2 diabetes mellitus are known to increase fracture risk. It is known that type 1 diabetes mellitus is associated with lower bone mineral density, but for type 2 diabetes mellitus, the real risk of increasing osteoporotic fractures is not explained by bone mineral density, which was found to be normal or paradoxically higher than controls in several studies, thus claiming for further investigations. This review summarizes some of the newest findings about factors that contribute to bone alterations in diabetic patients.

RECENT FINDINGS

Most recent evidences showed that bone of diabetic patients presents a cortical porosity which is not captured by the bidimensional densitometric measurements as performed by dual energy X-ray absorptiometry. Other studies investigated bone matrix searching for molecular mechanisms underlying the reduced bone strength in diabetic patients. The loss of bone biomechanical properties in diabetes has been associated to the glycated collagen matrix induced by hyperglycemia. Other studies analyzed the effect on bone microarchitecture of the most common antidiabetic drugs.

SUMMARY

Disease management of fracture risk in diabetic patients needs new methodologies of assessment that also take into account bone quality and evaluation of clinical risk factors, including balance, visual, and neurological impairments.

Use of Glucagon-Like-Peptide 1 Receptor Agonists and Risk of Fracture as Compared to Use of Other Anti-hyperglycemic Drugs

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a new class of drugs that might have a potential beneficial effect on bone metabolism. Data on the effect of GLP-1 RAs and fracture risk are lacking. The aim of the present study was to investigate the association between the use of GLP-1 and the risk of fracture. A case-control study was performed using Danish National Health Service data. Cases were those who sustained a fracture and controls were those without a fracture during the study period (2007-2011), all aged 18 years and above. Conditional logistic regression estimated the odds ratios (OR) of fracture with current use of DPP4-I use. Analyses were adjusted for comorbidities and recent drug use. Among cases (n = 229,114), there were 6993 current non-insulin anti-diabetic drug (NIAD) users (excluding incretin users) and 255 GLP-1 RA users. Similarly, among controls (n = 229,114), 7209 were NIAD users (excluding incretin users) and 220 were GLP-1 RA users. Current GLP-1 RA use was not associated with a decreased risk of fracture [adjusted (adj.) OR 1.16; 95% CI 0.83-1.63]. Osteoporotic fracture risk was also not associated with current GLP-1 RA use (adj. OR 0.78; 95% CI 0.44-1.39). In our nation-wide case-control study, we identified that the use of GLP-1 RA was not associated with fracture risk as compared to the use of other anti-hyperglycemic drugs. Additionally, current GLP-1 RA use, stratified by cumulative or average daily dose, is not associated with fracture risk. Further research should focus on long-term use of GLP-1 RA and fracture risk.

Oral anti-diabetic drugs and fracture risk, cut to the bone: safe or dangerous? A narrative review

Fracture risk is higher in older adults with type 2 diabetes and may be influenced by treatments for diabetes. Oral anti-diabetic drugs have different effects on bone metabolism. The purpose of this review is to describe the effects of these drugs on bone metabolism and fracture risk. Osteoporosis is a progressive skeletal disorder that is characterized by compromised bone strength and increased risk of fracture. This condition has become an important global health problem, affecting approximately 200 million people worldwide. Another chronic and highly prevalent condition is diabetes mellitus, which affects more than 380 million people; both type 1 and type 2 diabetes are risk factors for fracture. Type 2 diabetes, in particular, is associated with impaired bone strength, although it is characterized by normal or elevated bone mineral density. Several therapeutic strategies are available to achieve the best outcomes in the management of diabetes mellitus but these have different effects on bone metabolism. The purpose of this narrative review is to describe the effects of oral hypoglycemic agents (metformin, sulfonylureas, thiazolidinediones, meglitinides, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-dependent glucose transporter 2 inhibitors) on bone metabolism and on the risk of developing fragility fractures in patients with type 2 diabetes. Both diabetes and osteoporosis represent a significant burden in terms of healthcare costs and quality of life. It is very important to choose therapies for diabetes that ensure good metabolic control whilst preserving skeletal health.

Bone fracture risk is not associated with the use of glucagon-like peptide-1 receptor agonists: a population-based cohort analysis

Glucagon-like Peptide-1 receptor agonists (GLP1-ra) are a relatively new class of anti-hyperglycemic drugs which may positively affect bone metabolism and thereby decrease (osteoporotic) bone fracture risk. Data on the effect of GLP1-ra on fracture risk are scarce and limited to clinical trial data only. The aim of this study was to investigate, in a population-based cohort, the association between the use of GLP1-ra and bone fracture risk. We conducted a population-based cohort study, with the use of data from the Clinical Practice Research Datalink (CPRD) database (2007-2012). The study population (N = 216,816) consisted of all individuals with type 2 diabetes patients with at least one prescription for a non-insulin anti-diabetic drug and were over 18 years of age. Cox proportional hazards models were used to estimate the hazard ratio of fracture in GLP1-ra users versus never-GLP1-ra users. Time-dependent adjustments were made for age, sex, lifestyle, comorbidity and the use of other drugs. There was no decreased risk of fracture with current use of GLP1-ra compared to never-GLP1-ra use (adjusted HR 0.99, 95 % CI 0.82-1.19). Osteoporotic fracture risk was also not decreased by current GLP1-ra use (adjusted HR 0.97; 95 % CI 0.72-1.32). In addition, stratification according to cumulative dose did not show a decreased bone fracture risk with increasing cumulative GLP1-ra dose. We showed in a population-based cohort study that GLP1-ra use is not associated with a decreased bone fracture risk compared to users of other anti-hyperglycemic drugs. Future research is needed to elucidate the potential working mechanisms of GLP1-ra on bone.

Use of dipeptidyl peptidase 4 inhibitors and fracture risk compared to use of other anti-hyperglycemic drugs

INTRODUCTION

Dipeptidyl peptidase-4 inhibitors (DPP4-Is) are a new class of anti-hyperglycemic drugs which might have a potential beneficial effect on bone metabolism. Data on the effect of DPP4-I use and fracture risk is limited and conflicting. The aim of the present study was to investigate the association between use of DPP4-Is and fracture risk.

METHODS

A case-control study was conducted using data from the Danish National Health Service. Cases were those who sustained a fracture, and controls were those without a fracture during the study period (2007-2011), all aged 18 years and older. Conditional logistic regression estimated the odds ratios of fracture with current use of DPP4-I use. Analyses were adjusted for comorbidities and recent drug use.

RESULTS

Among the cases there were 6993 current non-insulin anti-diabetic drug (NIAD) users (excluding incretin users) and 643 DPP4-I users. There were 7209 NIAD users (excluding incretin users) among the controls and 707 DPP4-I users. Current DPP4-I use was not associated with risk of any fracture (adjusted [adj.] OR: 0.97, 95% CI: 0.79-1.18) or major osteoporotic fracture (adj. OR: 0.96, 95% CI: 0.72-1.28). Stratification of current DPP4-I use to cumulative and average daily dose did not show an association.

CONCLUSIONS

In a population-based case-control study we identified that short-term use of DPP4-I was not associated with fracture risk as compared to users of other anti-hyperglycemic drugs. Additionally, results suggest that increasing daily dose and cumulative DPP4-I exposure were not associated with fracture risk. However, more research is needed to assess the effect of long-term DPP4-I use on the risk of fracture.

Treatment escalation options for patients with type 2 diabetes after failure of exenatide twice daily or glimepiride added to metformin: results from the prospective European Exenatide (EUREXA) study

AIMS

To evaluate third-line thiazolidinedione (TZD) or glimepiride therapy in patients inadequately controlled on metformin + exenatide twice daily, and third-line exenatide twice daily in patients inadequately controlled on metformin + glimepiride.

METHODS

In this randomized, open-label, multicentre trial, 144 patients with type 2 diabetes inadequately controlled [glycated haemoglobin (HbA1c) >9% (75 mmol/mol) after 3 months' treatment or >7% (53 mmol/mol) at two consecutive visits 3 months apart, after 6 months' treatment] on metformin + exenatide twice daily were re-randomized to add-on TZD or glimepiride, and 166 patients inadequately controlled on metformin + glimepiride received add-on exenatide twice daily. Changes in HbA1c, body mass index (BMI), lipids, hypoglycaemia and vital signs were evaluated.

RESULTS

The median duration of triple therapy was ∼2 years. In patients inadequately controlled on metformin + exenatide twice daily, add-on TZD decreased HbA1c levels significantly better than add-on glimepiride: 130-week difference 0.48% [95% confidence interval (CI) 0.19-0.77] or 5.2 mmol/mol (95% CI 2.1-8.4; p = 0.001), but with significantly increased BMI and systolic blood pressure. The ratio of documented symptomatic (blood glucose ≤70 mg/dl [3.9 mmol/l]) hypoglycaemia rates for add-on glimepiride to add-on TZD was 8.48 (p < 0.0001). Add-on exenatide twice daily after metformin + glimepiride significantly reduced HbA1c levels: mean [standard deviation (s.d.)] change from baseline -0.35 (0.89)% [-3.8 (9.7) mmol/mol] and BMI: mean (s.d.) change from baseline -0.82 (1.9) kg/m(2) at 130 weeks, with a slightly increased rate of documented symptomatic hypoglycaemia from metformin + glimepiride (ratio 1.49).

CONCLUSIONS

TZD, but not glimepiride, was an effective and well tolerated third-line therapy in patients without glycaemic control after long-term therapy with metformin + exenatide twice daily. Exenatide twice daily was an effective and well tolerated third-line therapy in patients inadequately controlled on metformin + glimepiride.

Retrospective analysis of long-term adherence to and persistence with DPP-4 inhibitors in US adults with type 2 diabetes mellitus

Introduction

Patients with type 2 diabetes mellitus (T2DM) must remain adherent and persistent on antidiabetic medications to optimize clinical benefits. This analysis compared adherence and persistence among adults initiating dipeptidyl peptidase-4 inhibitors (DPP-4is), sulfonylureas (SUs), and thiazolidinediones (TZDs) and between patients initiating saxagliptin or sitagliptin, two DPP-4is.

Methods

This retrospective cohort study utilized the US MarketScan^® (Truven Health Analytics, Ann Arbor, MI, USA) Commercial and Medicare Supplemental health insurance claims databases. Adults aged ≥18 years with T2DM who initiated a DPP-4i, SU, or TZD from January 1, 2009 to January 31, 2012 were included. Patients must have been continuously enrolled for ≥1 year prior to and ≥1 year following initiation. Adherence was measured using proportion of days covered (PDC), with PDC ≥ 0.80 considered adherent. Persistence was measured as time to discontinuation, defined as last day with drug prior to a 60+ days gap in therapy. Multivariable logistic regression and Cox proportional hazards models compared the outcomes between cohorts, controlling for baseline differences.

Results

The sample included 238,372 patients (61,399 DPP-4i, 134,961 SU, 42,012 TZD). During 1-year follow-up, 47.3% of DPP-4i initiators, 41.2% of SU initiators, and 36.7% of TZD initiators were adherent. Adjusted odds of adherence were significantly greater among DPP-4i initiators than SU (adjusted odds ratio [AOR] = 1.678, P < 0.001) and TZD initiators (AOR = 1.605, P < 0.001). During 1-year follow-up, 55.0% of DPP-4i initiators, 47.8% of SU initiators, and 42.9% of TZD initiators did not discontinue therapy. Adjusted hazards of discontinuation were significantly greater for SU (adjusted hazard ratio [AHR] = 1.390, P < 0.001) and TZD initiators (AHR = 1.402, P < 0.001) compared with DPP-4i initiators. Saxagliptin initiators had significantly better adherence (AOR = 1.213, P < 0.001) compared with sitagliptin initiators, and sitagliptin initiators had significantly greater hazard of discontinuation (AHR = 1.159, P < 0.001). Results were similar over a 2-year follow-up.

Conclusions

US adults with T2DM who initiated DPP-4i therapy, particularly saxagliptin, had significantly better adherence and persistence compared with patients who initiated SUs or TZDs.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0171-3) contains supplementary material, which is available to authorized users.

Minireview: Challenges and opportunities in development of PPAR agonists

The clinical impact of the fibrate and thiazolidinedione drugs on dyslipidemia and diabetes is driven mainly through activation of two transcription factors, peroxisome proliferator-activated receptors (PPAR)-α and PPAR-γ. However, substantial differences exist in the therapeutic and side-effect profiles of specific drugs. This has been attributed primarily to the complexity of drug-target complexes that involve many coregulatory proteins in the context of specific target gene promoters. Recent data have revealed that some PPAR ligands interact with other non-PPAR targets. Here we review concepts used to develop new agents that preferentially modulate transcriptional complex assembly, target more than one PPAR receptor simultaneously, or act as partial agonists. We highlight newly described on-target mechanisms of PPAR regulation including phosphorylation and nongenomic regulation. We briefly describe the recently discovered non-PPAR protein targets of thiazolidinediones, mitoNEET, and mTOT. Finally, we summarize the contributions of on- and off-target actions to select therapeutic and side effects of PPAR ligands including insulin sensitivity, cardiovascular actions, inflammation, and carcinogenicity.

Cardiovascular impact of drugs used in the treatment of diabetes

The International Diabetes Federation predicts that by 2035 10% of the population of the world will have been diagnosed with diabetes, raising serious concerns over the resulting elevated morbidity and mortality as well as the impact on health care budgets. It is also well recognized that cardiovascular disease is the primary cause of the high morbidity and mortality associated with diabetes, raising the concern that appropriate drug therapy should not only correct metabolic dysfunction, but also protect the cardiovascular system from the effects of, in particular, the epigenetic changes that result from hyperglycaemia. A number of new classes of drugs for the treatment of diabetes have been introduced in the past decade, providing the opportunity to optimize treatment; however, comparative information of the cardiovascular benefits, or risks, of the newer drugs versus older therapies such as metformin is variable. This review, in addition to summarizing the cellular basis for the therapeutic action of these drugs, addresses the evidence for their cardiovascular benefits and risks. A particular focus is provided on metformin as it is the first choice drug for most patients with type 2 diabetes.

Use of dipeptidyl peptidase-4 inhibitors for type 2 diabetes mellitus and risk of fracture

INTRODUCTION

Although patients with type 2 diabetes mellitus have an increased bone mineral density as compared to healthy patients, their risk of fracture is elevated. Incretins, new anti-diabetic drugs, may have a protective effect on bone mineral density. However, data on the effect of incretins on fracture risk are limited. Therefore the aim of this study was to investigate the association between the use of DPP4-I and the risk of fracture.

METHODS

A retrospective population based cohort study, using data from the Clinical Practice Research Datalink (CPRD) database (2007-2012), was conducted. Patients (N=216,816) with at least one prescription for a non-insulin anti-diabetic drug (NIAD), aged 18+ during data collection, were matched to one control patient. Cox proportional hazards models were used to estimate the hazard ratio of any fracture in DPP4 inhibitor (DPP4-I) users versus controls and versus other NIAD patients. Time-dependent adjustments were made for age, sex, life style, comorbidity and drug use.

RESULTS

The actual duration of DPP4-I use was 1.3years. There was no different risk of fracture comparing current DPP4-I users to controls (adjusted hazard ratio (adj. HR) 0.89, 95% confidence interval (CI) 0.71-1.13). There was also no increased risk comparing current DPP4-I users to other NIAD users, adj. HR 1.03 (95% CI 0.92-1.15).

CONCLUSIONS

DPP4-I use was not associated with fracture risk compared to controls and to other NIAD users. However, the duration of DPP4-I use in our database might have been too short to show an association with fracture risk.

Risk of fracture with thiazolidinediones: an updated meta-analysis of randomized clinical trials

OBJECTIVE

The use of thiazolidinediones (TZDs) has been associated with increased fracture risk. We performed a comprehensive literature review and meta-analysis to estimate the risk of fractures with TZDs

METHODS

We searched MEDLINE, Embase and the Cochrane Database, from inception to May 2014. We included all randomized trials that described the risk of fractures or changes in bone mineral density (BMD) with TZDs. We pooled data with odds ratios (ORs) for fractures and the weighted mean difference in BMD. To assess heterogeneity in results of individual studies, we used Cochran's Q statistic and the I(2) statistic.

RESULTS

We included 24,544 participants with 896 fracture cases from 22 randomized controlled trials. Meta-analysis showed that the significantly increased incidence of fracture was found in women (OR=1.94; 95%CI: 1.60-2.35; P<0.001), but not in men (OR=1.02; 95%CI: 0.83-1.27; P=0.83). For women, the fracture risk was similar in rosiglitazone (OR=2.01; 95%CI: 1.61-2.51; P<0.001) and pioglitazone (OR=1.73; 95%CI: 1.18-2.55; P=0.005) treatment and appeared to be similar for participants aged <60years old (OR=1.89; 95%CI: 1.51-2.36; P<0.001) and aged ≥60years old (OR=2.07; 95%CI: 1.51-2.36; P<0.001). There was a non-significant trend towards increased risk of fractures in different cumulative durations of TZD exposure. TZD treatment was also associated with significant changes in BMD among women at the lumbar spine(weighted mean difference: -0.49%, 95%CI: -0.66% to -0.32%; P<0.001), the femoral neck (weighted mean difference: -0.34%, 95%CI: -0.51% to -0.16%; P<0.001) and the hip(weighted mean difference: -0.33%, 95%CI: -0.52% to -0.14%; P<0.001).

CONCLUSIONS

Our results suggest that TZD treatment is associated with an increased risk of fractures in women, effects of rosiglitazone and pioglitazone are similar, fracture risk is independent of age and fracture risk has no clear association with duration of TZD exposure.

Beneficial effects of Ginkgo biloba extract on insulin signaling cascade, dyslipidemia, and body adiposity of diet-induced obese rats

Ginkgo biloba extract (GbE) has been indicated as an efficient medicine for the treatment of diabetes mellitus type 2. It remains unclear if its effects are due to an improvement of the insulin signaling cascade, especially in obese subjects. The aim of the present study was to evaluate the effect of GbE on insulin tolerance, food intake, body adiposity, lipid profile, fasting insulin, and muscle levels of insulin receptor substrate 1 (IRS-1), protein tyrosine phosphatase 1B (PTP-1B), and protein kinase B (Akt), as well as Akt phosphorylation, in diet-induced obese rats. Rats were fed with a high-fat diet (HFD) or a normal fat diet (NFD) for 8 weeks. After that, the HFD group was divided into two groups: rats gavaged with a saline vehicle (HFD+V), and rats gavaged with 500 mg/kg of GbE diluted in the saline vehicle (HFD+Gb). NFD rats were gavaged with the saline vehicle only. At the end of the treatment, the rats were anesthetized, insulin was injected into the portal vein, and after 90s, the gastrocnemius muscle was removed. The quantification of IRS-1, Akt, and Akt phosphorylation was performed using Western blotting. Serum levels of fasting insulin and glucose, triacylglycerols and total cholesterol, and LDL and HDL fractions were measured. An insulin tolerance test was also performed. Ingestion of a hyperlipidic diet promoted loss of insulin sensitivity and also resulted in a significant increase in body adiposity, plasma triacylglycerol, and glucose levels. In addition, GbE treatment significantly reduced food intake and body adiposity while it protected against hyperglycemia and dyslipidemia in diet-induced obesity rats. It also enhanced insulin sensitivity in comparison to HFD+V rats, while it restored insulin-induced Akt phosphorylation, increased IRS-1, and reduced PTP-1B levels in gastrocnemius muscle. The present findings suggest that G. biloba might be efficient in preventing and treating obesity-induced insulin signaling impairment.

Molecular mechanism of thiazolidinedione-mediated inhibitory effects on osteoclastogenesis

Thiazolidinediones are synthetic peroxisome proliferator-activated receptor γ agonists used to treat type 2 diabetes mellitus. Clinical evidence indicates that thiazolidinediones increase fracture risks in type 2 diabetes mellitus patients, but the mechanism by which thiazolidinediones augment fracture risks is not fully understood. Several groups recently demonstrated that thiazolidinediones stimulate osteoclast formation, thus proposing that thiazolidinediones induce bone loss in part by prompting osteoclastogenesis. However, numerous other studies showed that thiazolidinediones inhibit osteoclast formation. Moreover, the molecular mechanism by which thiazolidinediones modulate osteoclastogenesis is not fully understood. Here we independently address the role of thiazolidinediones in osteoclastogenesis in vitro and furthermore investigate the molecular mechanism underlying the in vitro effects of thiazolidinediones on osteoclastogenesis. Our in vitro data indicate that thiazolidinediones dose-dependently inhibit osteoclastogenesis from bone marrow macrophages, but the inhibitory effect is considerably reduced when bone marrow macrophages are pretreated with RANKL. In vitro mechanistic studies reveal that thiazolidinediones inhibit osteoclastogenesis not by impairing RANKL-induced activation of the NF-κB, JNK, p38 and ERK pathways in bone marrow macrophages. Nonetheless, thiazolidinediones inhibit osteoclastogenesis by suppressing RANKL-induced expression of NFATc1 and c-Fos, two key transcriptional regulators of osteoclastogenesis, in bone marrow macrophages. In addition, thiazolidinediones inhibit the RANKL-induced expression of osteoclast genes encoding matrix metalloproteinase 9, cathepsin K, tartrate-resistant acid phosphatase and carbonic anhydrase II in bone marrow macrophages. However, the ability of thiazolidinediones to inhibit the expression of NFATc1, c-Fos and the four osteoclast genes is notably weakened in RANKL-pretreated bone marrow macrophages. These in vitro studies have not only independently demonstrated that thiazolidinediones exert inhibitory effects on osteoclastogenesis but have also revealed crucial new insights into the molecular mechanism by which thiazolidinediones inhibit osteoclastogenesis.

Osteoblast-targeted suppression of PPARγ increases osteogenesis through activation of mTOR signaling

Nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ) is an essential transcription factor for adipocyte differentiation. In mesenchymal stem cells, PPARγ has been assumed to play a negative role in osteoblastic differentiation, by working in an adipogenesis dependent manner, due to the reciprocal relationship between osteoblast and adipocyte differentiation. However, the direct role of PPARγ in osteoblast function is not fully understood, due in part to inadequate model systems. Here, we describe an adenoviral-mediated PPARγ knockout system in which suppression of PPARγ in mesenchymal stem cells enhanced osteoblast differentiation and inhibited adipogenesis in vitro. Consistent with this in vitro observation, lipoatrophic A-ZIP/F1 mice, which do not form adipocytes, displayed a phenotype in which both cortical and trabecular bone was significantly increased compared with wild-type mice. We next developed an inducible osteoblast-targeted PPARγ knockout (Osx Cre/flox- PPARγ) mouse to determine the direct role of PPARγ in bone formation. Data from both in vitro cultures of mesenchymal stem cells and in vivo µCT analysis of bones suggest that suppression of PPARγ activity in osteoblasts significantly increased osteoblast differentiation and trabecular number. Endogenous PPARγ in mesenchymal stem cells and osteoblasts strongly inhibited Akt/mammalian target of rapamycin (mTOR)/p70S6k activity and led to decreased osteoblastic differentiation. Therefore, we conclude that PPARγ modulates osteoblast differentiation and bone formation through both direct and indirect mechanisms. The direct mode, as shown here, involves PPARγ regulation of the mTOR pathway, while the indirect pathway is dependent on the regulation of adipogenesis.

Current clinical evidence on pioglitazone pharmacogenomics

Pioglitazone is the most widely used thiazolidinedione and acts as an insulin-sensitizer through activation of the Peroxisome Proliferator-Activated Receptor-γ (PPARγ). Pioglitazone is approved for use in the management of type 2 diabetes mellitus (T2DM), but its use in other therapeutic areas is increasing due to pleiotropic effects. In this hypothesis article, the current clinical evidence on pioglitazone pharmacogenomics is summarized and related to variability in pioglitazone response. How genetic variation in the human genome affects the pharmacokinetics and pharmacodynamics of pioglitazone was examined. For pharmacodynamic effects, hypoglycemic and anti-atherosclerotic effects, risks of fracture or edema, and the increase in body mass index in response to pioglitazone based on genotype were examined. The genes CYP2C8 and PPARG are the most extensively studied to date and selected polymorphisms contribute to respective variability in pioglitazone pharmacokinetics and pharmacodynamics. We hypothesized that genetic variation in pioglitazone pathway genes contributes meaningfully to the clinically observed variability in drug response. To test the hypothesis that genetic variation in PPARG associates with variability in pioglitazone response, we conducted a meta-analysis to synthesize the currently available data on the PPARG p.Pro12Ala polymorphism. The results showed that PPARG 12Ala carriers had a more favorable change in fasting blood glucose from baseline as compared to patients with the wild-type Pro12Pro genotype (p = 0.018). Unfortunately, findings for many other genes lack replication in independent cohorts to confirm association; further studies are needed. Also, the biological functionality of these polymorphisms is unknown. Based on current evidence, we propose that pharmacogenomics may provide an important tool to individualize pioglitazone therapy and better optimize therapy in patients with T2DM or other conditions for which pioglitazone is being used.

Bone loss in the oestrogen-depleted rat is not exacerbated by sitagliptin, either alone or in combination with a thiazolidinedione

Antihyperglycaemic therapy on bone was evaluated in the ovariectomized (OVX), non-diabetic adult rat. Animals were treated daily for 12 weeks with various doses of sitagliptin, pioglitazone, rosiglitazone, combinations of sitagliptin with pioglitazone or vehicle alone. Sitagliptin target engagement was confirmed by assessing inhibition of plasma dipeptidyl peptidase-4 (DPP-4) and oral glucose tolerance. Parameters related to bone health were evaluated in femur and vertebrae by dual-energy X-ray absorptiometry and histomorphometry. Bone mineral density (BMD) generally did not differ significantly between OVX-sitagliptin-treated animals and OVX-vehicle controls. In lumbar vertebrae, however, there was significantly less BMD loss with increasing sitagliptin dose. Thiazolidinedione (TZD) treatment generally resulted in lower BMD; OVX-TZD-treated (but not OVX-sitagliptin-treated) animals also had lessened cortical thickness in central femur and profoundly greater bone marrow adiposity in lumbar vertebrae. These findings support prior findings with TZDs and suggest a neutral or beneficial impact of DPP-4 inhibition on bone health.

Antidiabetic therapy effects on bone metabolism and fracture risk

Patients with diabetes are at greater risk of fractures mostly due to not only to extraskeletal factors, such as propensity to fall, but also to bone quality alteration, which reduces bone strength. In people with diabetes, insulin deficiency and hyperglycaemia seem to play a role in determining bone formation alteration by advanced glycation end product (AGE) accumulation or AGE/RAGE (receptors for AGE) axis imbalance, which directly influence osteoblast activity. Moreover, hyperglycaemia and oxidative stress are able to negatively influence osteocalcin production and the Wnt signalling pathways with an imbalance of osteoblast/osteoclast activity leading to bone quality reduction as global effect. In addition, other factors such as insulin growth factors and peroxisome proliferator-activated receptor-γ pathways seem to have an important role in the pathophysiology of osteoporosis in diabetes. Although there are conflicting data in literature, adequate glycaemic control with hypoglycaemic treatment may be an important element in preventing bone tissue alterations in both type 1 and type 2 diabetes. Attention should be paid to the use of thiazolidinediones, especially in older women, because the direct negative effect on bone could exceed the positive effect of glycaemic control. Finally, preliminary data on animals and in humans suggest the hypothesis that incretins and dipeptidyl peptidase-4 inhibitors could have a positive effect on bone metabolism by a direct effect on bone cells; however, such issue needs further investigations.

Pleiotropic effects of thiazolidinediones: implications for the treatment of patients with type 2 diabetes mellitus

Thiazolidinediones (TZDs) are insulin-sensitizing antidiabetes agents that act through the peroxisome proliferator-activated receptor-γ to cause a durable improvement in glycemic control in patients with type 2 diabetes mellitus. Although less well recognized, TZDs also exert a protective effect on β-cell function. In addition to their beneficial effects on glucose homeostasis, TZDs-especially pioglitazone-exert a number of other pleiotropic effects that make them ideal agents as monotherapy or in combination with other oral agents, glucagon-like peptide-1 analogs, or insulin. Pioglitazone improves endothelial dysfunction, reduces blood pressure, corrects diabetic dyslipidemia, and reduces circulating levels of inflammatory cytokines and prothrombotic factors. Pioglitazone also redistributes fat and toxic lipid metabolites in muscle, liver, β cells, and arteries, and deposits the fat in subcutaneous adipocytes where it cannot exert its lipotoxic effects. Consistent with these antiatherogenic effects, pioglitazone reduced major adverse cardiac event endpoints (ie, mortality, myocardial infarction, and stroke) in the Prospective Pioglitazone Clinical Trial in Macrovascular Events and in a meta-analysis of all other published pioglitazone trials. Pioglitazone also mobilizes fat out of the liver, improving liver function and histologic abnormalities in patients with nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Pioglitazone also reduces proteinuria, all-cause mortality, and cardiovascular events in patients with type 2 diabetes mellitus with a reduced glomerular filtration rate. These benefits must be weighed against the side effects of the drug, including weight gain, fluid retention, atypical fractures, and, possibly, bladder cancer. When low doses of pioglitazone are used (eg, 7.5-30 mg/d) with gradual titration, and physician recognition of the potential side effects are applied, the risk-to-benefit ratio is very favorable. Despite having similar effects on glycemic control, pioglitazone and rosiglitazone appear to have different effects on cardiovascular outcomes. Rosiglitazone has been associated with an increased risk of myocardial infarction, and its use in the United States is restricted because of cardiovascular safety concerns.

Pharmacokinetic considerations for the treatment of diabetes in patients with chronic kidney disease

INTRODUCTION

People with chronic kidney disease (CKD) of stages 3 - 5 (creatinine clearance < 60 ml/min) represent ≈ 25% of patients with type 2 diabetes mellitus (T2DM), but the problem is underrecognized or neglected in clinical practice. However, most oral antidiabetic agents have limitations in case of renal impairment (RI), either because they require a dose adjustment or because they are contraindicated for safety reasons.

AREAS COVERED

The author performed an extensive literature search to analyze the influence of RI on the pharmacokinetics (PK) of glucose-lowering agents and the potential consequences for clinical practice.

EXPERT OPINION

As a result of PK interferences and for safety reasons, the daily dose should be reduced according to glomerular filtration rate (GFR) or even the drug is contraindicated in presence of severe CKD. This is the case for metformin (risk of lactic acidosis) and for many sulfonylureas (risk of hypoglycemia). At present, however, the exact GFR cutoff for metformin use is controversial. New antidiabetic agents are better tolerated in case of CKD, although clinical experience remains quite limited for most of them. The dose of DPP-4 inhibitors should be reduced (except for linagliptin), whereas both the efficacy and safety of SGLT2 inhibitors are questionable in presence of CKD.