Combined thiazolidinedione-insulin therapy: should we be concerned about safety?

Comparison of Glucagon-Like Peptide-1 Receptor Agonists and Sodium-Glucose Cotransporter Protein-2 Inhibitors on Treating Metabolic Dysfunction-Associated Steatotic Liver Disease or Metabolic Dysfunction-Associated Steatohepatitis: Systematic Review and Network Meta-Analysis of Randomised Controlled Trials

OBJECTIVE

To assess glucagon-like peptide-1 receptor agonists (GLP-1 receptor agonists) and sodium-glucose cotransporter protein-2 inhibitors (SGLT-2 inhibitors) in patients with metabolic dysfunction-associated steatotic liver disease or metabolic dysfunction-associated steatohepatitis (previously known as nonalcoholic fatty liver disease [NAFLD] and nonalcoholic steatohepatitis [NASH]), we performed a systematic review and network meta-analysis of randomized controlled trials.

METHODS

The study searched Pubmed, Embase, the Cochrane Library, and Web of Science databases up to November 26, 2023. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias.

RESULTS

Thirty-seven studies were included in the analysis. GLP-1 receptor agonists were found to be more effective than placebo in resolving NASH (relative risk: 2.48, 95% CI:1.86 to 3.30). Both drugs were superior to placebo in reducing liver fat content, as well as decreasing levels of liver enzyme. Network meta-analysis indicated that SGLT-2 inhibitors were more effective than GLP-1 receptor agonists in reducing alanine aminotransferase and aspartate aminotransferase levels. According to the surface under the cumulative probability ranking curve values, GLP-1 receptor agonists and SGLT-2 inhibitors consistently ranked among the top 2 in terms of reducing anthropometric data compared to other included drugs.

CONCLUSIONS

GLP-1 receptor agonists and SGLT-2 inhibitors have significant effects on reducing liver fat content and liver enzymes in NAFLD or NASH patients compared to placebo. GLP-1 receptor agonists were found to be superior to placebo in resolving NASH. SGLT-2 inhibitors were more effective than GLP-1 receptor agonists in reducing alanine aminotransferase and aspartate aminotransferase levels.

Approach to the Patient with Non-cardiac Leg Swelling

One of the most common reasons for patient visits in the outpatient practice is lower extremity swelling. Non-cardiac etiologies are the most frequent reason for these encounters. The approach to this patient population will focus on the 7 key questions to initiate the gathering of historical information on the etiology of leg swelling. Figures and tables will complement the text for diagnosing lower extremity swelling. In this article, the common non-cardiac etiologies will be reviewed which include medications, chronic venous insufficiency, lymphatic disease, lipedema, venous thrombosis, and musculoskeletal etiologies.

From an Apple to a Pear: Moving Fat around for Reversing Insulin Resistance

Type 2 diabetes (T2D) is a chronic condition where the body is resistant to insulin, leading to an elevated blood glucose state. Obesity is a main factor leading to T2D. Many clinical studies, however, have described a proportion of obese individuals who express a metabolically healthy profile, whereas some lean individuals could develop metabolic disorders. To study obesity as a risk factor, body fat distribution needs to be considered rather than crude body weight. Different individuals' bodies favor storing fat in different depots; some tend to accumulate more fat in the visceral depot, while others tend to store it in the femoral depot. This tendency relies on different factors, including genetic background and lifestyle. Consuming some types of medications can cause a shift in this tendency, leading to fat redistribution. Fat distribution plays an important role in the progression of risk of insulin resistance (IR). Apple-shaped individuals with enhanced abdominal obesity have a higher risk of IR compared to BMI-matched pear-shaped individuals, who store their fat in the gluteal-femoral depots. This is related to the different adipose tissue physiology between these two depots. In this review, we will summarize the recent evidence highlighting the underlying protective mechanisms in gluteal-femoral subcutaneous adipose tissues compared to those associated with abdominal adipose tissue, and we will revise the recent evidence showing antidiabetic drugs that impact fat distribution as they manage the T2D condition.

Practical Guidance on Basal Insulin Initiation and Titration in Asia: A Delphi-Based Consensus

The global health burden of diabetes is on the rise and has affected more than half a billion people worldwide, particularly in Southeast Asia, North Africa, Africa, and the Western Pacific, Middle East, and South and Central America regions of the International Diabetes Federation (IDF). Despite many new treatments being available for the management of diabetes, glycemic control remains suboptimal in Asia, compared to the rest of the world. Delay in timely insulin initiation and inadequate titration of insulin are regarded to be some of the important reasons for inadequate glycemic control. Additionally, Asian populations have a distinct phenotype, including a younger age of onset and higher glycemic excursions, suggestive of a lower beta-cell function, as compared to non-Asians. Although there are multiple local and international guidelines on insulin initiation and titration, some of these guidelines can be complex. There is an unmet need for guideline recommendations on basal insulin initiation and titration to be simplified and customized for the Asian population with type 2 diabetes mellitus (T2DM). A unified approach would increase adoption of basal insulin initiation by primary care and family medicine physicians, which in turn would help reduce the inertia to insulin initiation. With this background, a consensus-seeking meeting was conducted with 14 experts from seven Asian countries to delineate appropriate practices for insulin initiation and titration in the Asian context. The key objective was to propose a simple insulin titration algorithm, specific for the Asian population, to improve glycemic control and optimize therapeutic outcomes of people with T2DM on basal insulin. Following a detailed review of literature and current guidelines, and potential barriers to insulin initiation and titration, the experts proposed a simplified insulin titration algorithm based on both physician- and patient-led components. The consensus recommendations of the experts related to basal insulin initiation and titration have been summarized in this article, along with the proposed titration algorithm for optimizing glycemic control in the Asian population with T2DM.

Drug-Related Lymphedema: Mysteries, Mechanisms, and Potential Therapies

The lymphatic circulation is an important component of the circulatory system in humans, playing a critical role in the transport of lymph fluid containing proteins, white blood cells, and lipids from the interstitial space to the central venous circulation. The efficient transport of lymph fluid critically relies on the rhythmic contractions of collecting lymph vessels, which function to "pump" fluid in the distal to proximal direction through the lymphatic circulation with backflow prevented by the presence of valves. When rhythmic contractions are disrupted or valves are incompetent, the loss of lymph flow results in fluid accumulation in the interstitial space and the development of lymphedema. There is growing recognition that many pharmacological agents modify the activity of ion channels and other protein structures in lymph muscle cells to disrupt the cyclic contraction and relaxation of lymph vessels, thereby compromising lymph flow and predisposing to the development of lymphedema. The effects of different medications on lymph flow can be understood by appreciating the intricate intracellular calcium signaling that underlies the contraction and relaxation cycle of collecting lymph vessels. For example, voltage-sensitive calcium influx through long-lasting ("L-type") calcium channels mediates the rise in cytosolic calcium concentration that triggers lymph vessel contraction. Accordingly, calcium channel antagonists that are mainstay cardiovascular medications, attenuate the cyclic influx of calcium through L-type calcium channels in lymph muscle cells, thereby disrupting rhythmic contractions and compromising lymph flow. Many other classes of medications also may contribute to the formation of lymphedema by impairing lymph flow as an off-target effect. The purpose of this review is to evaluate the evidence regarding potential mechanisms of drug-related lymphedema with an emphasis on common medications administered to treat cardiovascular diseases, metabolic disorders, and cancer. Additionally, although current pharmacological approaches used to alleviate lymphedema are largely ineffective, efforts are mounting to arrive at a deeper understanding of mechanisms that regulate lymph flow as a strategy to identify novel anti-lymphedema medications. Accordingly, this review also will provide information on studies that have explored possible anti-lymphedema therapeutics.

Careful use to minimize adverse events of oral antidiabetic medications in the elderly

INTRODUCTION

An increasing number of older patients has type 2 diabetes treated with different oral antidiabetic agents whose safety may raise concern considering some particularities of a heterogeneous elderly population.

AREAS COVERED

This article discusses some characteristics of older patients that could increase the risk of adverse events, with a focus on hypoglycemia. It describes the most frequent and/or severe complications reported in the elderly in both randomized controlled trials and observational studies with metformin, sulfonylureas, meglitinides, alpha-glucosidase inhibitors, thiazolidinediones, dipeptidyl peptidase-4 inhibitors (gliptins) and sodium-glucose cotransporter type 2 inhibitors (gliflozins).

EXPERT OPINION

Old patients may present comorbidities (renal impairment, vascular disease, heart failure, risk of dehydration, osteoporosis, cognitive dysfunction) that could increase the risk of severe adverse events. Sulfonylureas (and meglitinides) induce hypoglycemia, which may be associated with falls/fractures and cardiovascular events. Medications lacking hypoglycemia should be preferred. Gliptins appear to have the best tolerance/safety profile whereas gliflozins exert a cardiorenal protection. However, data are lacking in very old or frailty old patients so that caution and appropriate supervision of such patients are required. Taking advantage of a large choice of pharmacotherapies, personalized treatment is recommended based upon both drug safety profiles and old patient individual characteristics.

Heart Failure in Diabetes Mellitus: An Updated Review

Diabetes mellitus (DM) and heart failure (HF) are comorbid conditions associated with significant morbidity and mortality worldwide. Despite the availability of novel and effective therapeutic options and intensive glycaemic control strategies, mortality and hospitalisation rates continue to remain high and the incidence of HF persists. In this review, we described the impact of currently available glucose-lowering therapies in DM with a focus on HF clinical outcomes. Non-conventional modes of management and alternative pathophysiological mechanisms with the potential for therapeutic targeting are also discussed.

The Selective Peroxisome Proliferator-Activated Receptor Gamma Modulator CHS-131 Improves Liver Histopathology and Metabolism in a Mouse Model of Obesity and Nonalcoholic Steatohepatitis

CHS-131 is a selective peroxisome proliferator-activated receptor gamma modulator with antidiabetic effects and less fluid retention and weight gain compared to thiazolidinediones in phase II clinical trials. We investigated the effects of CHS-131 on metabolic parameters and liver histopathology in a diet-induced obese (DIO) and biopsy-confirmed mouse model of nonalcoholic steatohepatitis (NASH). Male C57BL/6JRj mice were fed the amylin liver NASH diet (40% fat with trans-fat, 20% fructose, and 2% cholesterol). After 36 weeks, only animals with biopsy-confirmed steatosis and fibrosis were included and stratified into treatment groups (n = 12-13) to receive for the next 12 weeks (1) low-dose CHS-131 (10 mg/kg), (2) high-dose CHS-131 (30 mg/kg), or (3) vehicle. Metabolic parameters, liver pathology, metabolomics/lipidomics, markers of liver function and liver, and subcutaneous and visceral adipose tissue gene expression profiles were assessed. CHS-131 did not affect body weight, fat mass, lean mass, water mass, or food intake in DIO-NASH mice with fibrosis. CHS-131 improved fasting insulin levels and insulin sensitivity as assessed by the intraperitoneal insulin tolerance test. CHS-131 improved total plasma cholesterol, triglycerides, alanine aminotransferase, and aspartate aminotransferase and increased plasma adiponectin levels. CHS-131 (high dose) improved liver histology and markers of hepatic fibrosis. DIO-NASH mice treated with CHS-131 demonstrated a hepatic shift to diacylglycerols and triacylglycerols with a lower number of carbons, increased expression of genes stimulating fatty acid oxidation and browning, and decreased expression of genes promoting fatty acid synthesis, triglyceride synthesis, and inflammation in adipose tissue. Conclusion: CHS-131 improves liver histology in a DIO and biopsy-confirmed mouse model of NASH by altering the hepatic lipidome, reducing insulin resistance, and improving lipid metabolism and inflammation in adipose tissue.

Prospect of Sodium-Glucose Co-transporter 2 Inhibitors Combined With Insulin for the Treatment of Type 2 Diabetes

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are a new family of antidiabetic drugs that reduce blood glucose independent of insulin. In this review, we present the advantages and adverse effects of SGLT2 inhibitors plus insulin therapy as a treatment regimen for patients with type 2 diabetes (T2D). Compared with placebo, SGLT2 inhibitors plus insulin therapy could significantly decrease fasting blood glucose and HbA1c, thereby reducing the daily required dose of insulin. A reduction in body weight and improvements in insulin resistance and β-cell function have also been widely reported with this therapy, and other potential advantages, including the reduction in blood pressure, adverse cardiovascular outcomes, and visceral adipose tissue volume, have been revealed. SGLT2 inhibitors cause a greater reduction than dipeptidyl peptidase-4 (DPP-4) inhibitors in body weight and the risk of cardiovascular disease. Furthermore, compared with glucagon-like peptide-1 (GLP-1) agonists, SGLT2 inhibitors reduce blood pressure, and heart failure. As this therapy is an oral preparation, an improvement in patient compliance is also achieved. Despite these advantages, however, combination therapy with SGLT2 inhibitors and insulin has several risks. Although no difference has been found in the incidence of hypoglycemic events and urinary tract infection between the administration of this combination and that of placebo, the risk of genital tract infections was reported to increase with the combination therapy. Additionally, bone adverse effects, euglycemic diabetic ketoacidosis, and volume depletion-and osmotic diuresis-related adverse effects have been observed. Altogether, we could conclude that SGLT2 inhibitors plus insulin therapy is an efficient treatment option for patients with T2D, especially those requiring high daily insulin doses and those with insulin resistance, obesity, and a high risk of cardiovascular events. However, careful monitoring of the adverse effects of this combination is also warranted.

BE-SMART (Basal Early Strategies to Maximize HbA1c Reduction with Oral Therapy): Expert Opinion

The past three decades have seen a quadruple rise in the number of people affected by diabetes mellitus worldwide, with the disease being the ninth major cause of mortality. Type 2 diabetes mellitus (T2DM) often remains undiagnosed for several years due to its asymptomatic nature during the initial stages. In India, 70% of diagnosed diabetes cases remain uncontrolled. Current guidelines endorse the initiation of insulin early in the course of the disease, specifically in patients with HbA1c > 10%, as the use of oral agents alone is unlikely to achieve glycemic targets. Early insulin initiation and optimization of glycemic control using insulin titration algorithms and patient empowerment can facilitate the effective management of uncontrolled diabetes. Early glucose control has sustained benefits in people with diabetes. However, insulin initiation, dose adjustment, and the need to repeatedly assess blood glucose levels are often perplexing for both physicians and patients, and there are misconceptions and concerns regarding its use. Hence, an early transition to insulin and ideal intensification of treatment may aid in delaying the onset of diabetes complications. This opinion statement was formulated by an expert panel on the basis of existing guidelines, clinical experience, and economic and cultural contexts. The statement stresses the timely and appropriate use of basal insulin in T2DM. It focuses on the seven vital Ts-treatment initiation, timing of administration, transportation and storage, technique of administration, targets for titration, tablets, and tools for monitoring.Funding: Sanofi.

Supercritical Fluid-Assisted Decoration of Nanoparticles on Porous Microcontainers for Codelivery of Therapeutics and Inhalation Therapy of Diabetes

The impact of nanotechnology and its advancements have allowed us to explore new therapeutic modalities. To this end, we designed nanoparticles-inlaid porous microparticles (NIPMs) coloaded with small interfering RNA (siRNA) and glucagon-like peptide-1 (GLP-1) using the supercritical carbon dioxide (SC-CO₂) technology as an inhalation delivery system for diabetes therapy. siRNA-encapsulating chitosan (CS) nanoparticles were first synthesized by an ionic gelation method, which resulted in particles with small sizes (100-150 nm), high encapsulation efficiency (∼94.8%), and sustained release performance (∼60% in 32 h). These CS nanoparticles were then loaded with GLP-1-dispersed poly-l-lactide (PLLA) porous microparticles (PMs) by SC-CO₂-assisted precipitation with the compressed antisolvent (PCA) process. The hypoglycemic efficacy of NIPMs administered via pulmonary route in mice persisted longer due to sustained release of siRNA from CS nanoparticles and the synergistic effects of GLP-1 in PMs, which significantly inhibited the expression of dipeptidyl peptidase-4 mRNA (DPP-4-mRNA). This ecofriendly technology provides a convenient way to fabricate nanoparticle-microparticle composites for codelivery of a gene and a therapeutic peptide, which will potentially find widespread applications in the field of pharmaceutics.

Pharmacotherapy of type 2 diabetes: An update

Type 2 diabetes (T2DM) is a leading cause of morbidity and mortality worldwide and a major economic burden. The prevalence of T2DM is rising, suggesting more effective prevention and treatment strategies are necessary. The aim of this narrative review is to summarize the pharmacologic treatment options available for patients with T2DM. Each therapeutic class is presented in detail, outlining medication effects, side effects, glycemic control, effect on weight, indications and contraindications, and use in selected populations (heart failure, renal insufficiency, obesity and the elderly). We also present representative cost for each antidiabetic category. Then, we provide an individualized guide for initiation and intensification of treatment and discuss the considerations and rationale for an individualized glycemic goal.

Controversy of oral hypoglycemic agents in type 2 diabetes mellitus: Novel move towards combination therapies

AIM

As diabetes mellitus is multi-factorial disease, use of several oral hypoglycemic agents (OHAs) is the main stay of pharmacological treatment. The treatment has become more challenging and controversial as OHAs are heterogeneous in their mode of action that causes unwanted side effects. Complementary approaches such as use of medicinal plants and dietary polyunsaturated fatty acids (PUFA) with hypoglycemic and hypolipidemic activities are therefore imperative. A vast literature has independently documented the effects of OHAs, medicinal plants and PUFA for management of diabetes. In the present article, we have reviewed the current literature to describe the effects of commonly used OHAs, their mechanisms of action and reported controversies. The antidiabetic potential of herbs and/or formulations and omega-3 PUFA with its potential benefits and mode of action is also discussed.

METHODS

PUBMED, MEDLINE, Cochrane Library etc., were searched for relevant articles using appropriate terms (until February 2015). Human and animal studies were selected for the review. Data extraction was carried out by one author and checked by second author.

RESULTS

There is still controversy over the safety profile of OHAs. Medicinal herbs with hypoglycemic activities are increasingly sought because of its natural origin, active constituents and minimal side effects. The current literature suggests that supplementation with PUFA improves macro- and microvascular complications.

CONCLUSION

There is a need for best possible individualized treatment based on variations in biochemical parameters with combinational therapy of nutritional/herbal supplementations. Such a combination may be helpful for better management of diabetes and its complications.

Pharmacotherapy of 'treatment resistant' type 2 diabetes

INTRODUCTION

Despite type 2 diabetes (T2D) management offers a variety of pharmacological interventions targeting different defects, numerous patients remain with persistent hyperglycaemia responsible for severe complications. Unlike resistant hypertension, treatment resistant T2D is not a classical concept although it is a rather common observation in clinical practice. Areas covered: This article proposes a definition for 'treatment resistant diabetes', analyses the causes of poor glucose control despite standard therapy, briefly considers the alternative approaches to glucose-lowering pharmacotherapy and finally describes how to overcome poor glycaemic control, using innovative oral or injectable combination therapies. Expert opinion: Before considering intensifying the pharmacotherapy of a patient with poorly controlled T2D, it is important to verify treatment adherence, target obesity and consider various non pharmacological improvement quality interventions. If treatment resistant diabetes is defined as not achieving glycated haemoglobin target despite oral triple therapy with a third glucose-lowering agent added to metformin-sulfonylurea dual treatment, the combination of a dipeptidyl peptidase-4 (DPP-4) inhibitor and a sodium glucose cotransporter type 2 (SGLT2) inhibitor may offer new opportunities before considering injectable therapies. Insulin basal therapy (± metformin) may be optimized by the addition of a SGLT2 inhibitor or a glucagon-like peptide-1 (GLP-1) receptor agonist.

Practical combination therapy based on pathophysiology of type 2 diabetes

Type 2 diabetes is a complex, chronic, and progressive condition that often necessitates the use of multiple medications to achieve glycemic goals. Clinical guidelines generally recommend intensifying pharmacotherapy if glycemic goals are not achieved after 3 months of treatment. However, for many patients with type 2 diabetes, treatment intensification is delayed or does not occur. Initiating combination therapy early in the disease course has the potential to delay disease progression and improve patient outcomes. Guidelines generally provide a list of agents that may be used in combination regimens and emphasize individualization of treatment. The purpose of this review is to discuss the rationale for combination therapy, considering treatment effects on pathophysiologic aspects of type 2 diabetes and individual drug profiles. The combination of newer antidiabetes therapies with complementary mechanisms of action provides the opportunity to target multiple sites of tissue, organ, and cellular dysfunction.

Dual Peroxisome Proliferator-Activated Receptor-alpha/gamma Agonists : In the Treatment of Type 2 Diabetes Mellitus and the Metabolic Syndrome

The metabolic syndrome consists of a combination of cardiovascular risk factors that include hyperglycemia with or without type 2 diabetes mellitus, visceral obesity, elevated blood pressure, and atherogenic dyslipidemia. These interrelated disorders and their associated lipotoxicity, oxidative stress, and inflammatory state predispose to a constellation of cardiovascular conditions leading to high risk of heart attack, stroke, renal failure, blindness, and lower extremity amputation. Visceral obesity, a prime risk factor for type 2 diabetes and a major component of the metabolic syndrome, potentiates atherogenesis, atherosclerosis, organ lipotoxicity, and oxidative tissue damage.Peroxisome proliferator-activated receptors (PPARs) are relatively recently discovered nuclear transcription factors that are modulated by dietary fatty acids, including the essential polyunsaturated fatty acids, arachidonic acid and its metabolites, and are essential to the control of energy metabolism. Of the three PPAR isoforms (alpha, gamma, and delta), synthetic pharmaceutical ligands that activate PPARalpha (the antidyslipidemic fibric acid derivatives ['fibrates']) and PPARgamma (the antidiabetic thiazolidinediones) have been studied extensively. Recently developed dual PPARalpha/gamma agonists may combine the therapeutic effects of these drugs, creating the expectation of greater efficacy, and perhaps other advantages in the treatment of type 2 diabetes and the metabolic syndrome. However, thiazolidinediones are hampered by adverse effects related to increased weight gain and fluid overload. It remains to be seen whether the dual PPARalpha/gamma agonists currently under development have similar limitations. Nevertheless, existing clinical data imply that the combined effects of thiazolidinediones and fibrates are likely to be emulated by dual PPARalpha/gamma agonists, providing superior efficacy to these classes for the treatment of type 2 diabetes, the metabolic syndrome, and their cardiovascular and other end-organ complications.

Antiallergic Function of KR62980, a Peroxisome Proliferator-Activated Receptor-γ Agonist, in a Mouse Allergic Rhinitis Model

PURPOSE

Peroxisome proliferator-activated receptor γ (PPAR-γ) has been shown to play an important role in the control of inflammatory responses acting on macrophages, mast cells, T cells and eosinophils. A novel PPAR-γ ligand, KR62980 have been recently focused on due to the lower undesirable effects than other PPAR-γ ligands such as rosiglitazone and pioglitazone. The present study was aimed to investigate the effects of KR62980 on nasal symptoms and immunopathological profiles in allergic nasal mucosa in murine allergic rhinitis model.

METHODS

BALB/c mice were sensitized and challenged intranasally with ovalbumin (OVA). KR62980 was administered intraperitoneally or orally 3 hours before each intranasal OVA challenge.

RESULTS

Administration of KR62980 significantly decreased the number of nasal rubbing, nasal sneezing, ova-specific IgE and total IgE in serum, secretion of Interleukin (IL)-4, IL-5, and IL-17 from the spleen and eosinophilic infiltration in the nasal mucosa. KR62980 decreased the expression of IL-4, IL-5 and IL-10 mRNAs in the nasal mucosal tissue, while, it elevated the level of IL-10 and IFN-γ in splenocyte culture. KR62980 seemed to decrease IL-17 level in local and systemic level even though it did not reach to statistical significance. The anti-inflammatory effect was more definite when the KR62980 was administered intraorally than intraperitoneally.

CONCLUSIONS

A novel PPAR-γ ligand, KR62980 can attenuate OVA-induced allergic inflammation in mice mainly through modulation of Th2 cytokines. This finding suggests that PPAR-γ might have a role in the treatment of allergic rhinitis.

Impact of Bromocriptine-QR Therapy on Glycemic Control and Daily Insulin Requirement in Type 2 Diabetes Mellitus Subjects Whose Dysglycemia Is Poorly Controlled on High-Dose Insulin: A Pilot Study

BACKGROUND

The concurrent use of a postprandial insulin sensitizing agent, such as bromocriptine-QR, a quick release formulation of bromocriptine, a dopamine D2 receptor agonist, may offer a strategy to improve glycemic control and limit/reduce insulin requirement in type 2 diabetes (T2DM) patients on high-dose insulin. This open label pilot study evaluated this potential utility of bromocriptine-QR.

METHODS

Ten T2DM subjects on metformin (1-2 gm/day) and high-dose (TDID ≥ 65 U/day) basal-bolus insulin were enrolled to receive once daily (morning) bromocriptine-QR (1.6-4.8 mg/day) for 24 weeks. Subjects with at least one postbaseline HbA1c measurement (N = 8) were analyzed for change from baseline HbA(1c), TDID, and postprandial glucose area under the curve of a four-hour mixed meal tolerance test (MMTT).

RESULTS

Compared to the baseline, average HbA1c decreased 1.76% (9.74 ± 0.56 to 7.98 ± 0.36, P = 0.01), average TDID decreased 27% (199 ± 33 to 147 ± 31, P = 0.009), and MMTT AUC(60-240) decreased 32% (P = 0.04) over the treatment period. The decline in HbA(1c) and TDID was observed at 8 weeks and sustained over the remaining 16-week study duration.

CONCLUSION

In this study, bromocriptine-QR therapy improved glycemic control and meal tolerance while reducing insulin requirement in T2DM subjects poorly controlled on high-dose insulin therapy.

Peroxisome proliferator-activated receptor activating hypoglycemic effect of Gardenia jasminoides Ellis aqueous extract and improvement of insulin sensitivity in steroid induced insulin resistant rats

Background

The active components of Gardenia (Gardenia jasminoides Ellis, GJ) exhibit a hypoglycemic effect by improving insulin secretion and lowering plasma lipids. In the present study, we fed a water extract of gardenia to steroid-induced insulin-resistant (SIIR) rats and observed changes in signaling proteins in order to elucidate the mechanisms of the insulin-sensitizing effect of GJ and evaluate its possibility as an insulin-sensitizing agent.

Methods

Normal Wistar rats were randomly divided into a control group (i.e., saline) and experimental groups (GJ 100 and 200 mg/kg). Blood samples were taken at 0, 30, and 60 min for plasma glucose assay in order to determine the optimal dose to induce the hypoglycemic effect. SIIR rats were then randomly divided into a control group (i.e., saline) and an experimental group (optimal dose of gardenia extract) to observe the insulin-sensitizing effect of the extract. Finally, western blot analysis was performed to detect intracellular signaling proteins to elucidate the mechanisms of the insulin-sensitization effect of GJ.

Results

The normal Wistar rats in the GJ 200 mg/kg group exhibited significant hypoglycemic activity. Meanwhile, the SIIR rats had higher plasma glucose levels than normal rats. There was no obvious change in insulin level, but the insulin sensitivity index and homeostasis model assessment index were significantly elevated. Meanwhile, a significant hypoglycemic effect was observed with GJ 200 mg/kg. In addition, intracellular signaling proteins including insulin receptor substrate-1 (IRS-1) and peroxisome proliferator-activated receptor (PPARγ) were elevated in muscle cells.

Conclusions

The optimal dose of GJ aqueous extract of 200 mg/kg exerts a PPARγ-activating hypoglycemic effect and improves insulin resistance in SIIR rats. Therefore, it is a potential insulin-sensitizing agent in type 2 diabetes mellitus with insulin resistance.

Role of PPARs in inflammatory processes associated with metabolic syndrome (Review)

Metabolic syndrome (MS) includes the presence of arterial hypertension, insulin resistance, dyslipidemia, cardiovascular disease (CVD) and abdominal obesity, which is associated with a chronic inflammatory response, characterized by abnormal adipokine production, and the activation of certain pro-inflammatory signaling pathways. Furthermore, the changes presented by the adipose tissue in MS favors the secretion of several molecular mediators capable of activating or suppressing a number of transcription factors, such as the peroxisome proliferator-activated receptors (PPARs), whose main functions include storage regulation and fatty acid catabolization. When they are activated by their ligands (synthetic or endogenous), they control several genes involved in intermediate metabolism, which make them, together with the PPAR gamma coactivator-1-α (PGC-1) and the silent information regulator T1 (SIRT1), good targets for treating metabolic diseases and their cardiovascular complications.

The future of thiazolidinedione therapy in the management of type 2 diabetes mellitus

Since their approval, thiazolidinediones (TZDs) have been used extensively as insulin-sensitizers for the management of type 2 diabetes mellitus (T2DM). Activation of peroxisomal proliferator-activated receptor gamma (PPARγ) nuclear receptors by TZDs leads to a vast spectrum of metabolic and antiinflammatory effects. In the past decade, clinicians and scientists across the fields of metabolism, diabetes, liver disease (NAFLD), atherosclerosis, inflammation, infertility, and even cancer have had high hopes about the potential for TZDs to treat many of these diseases. However, an increasing awareness about undesirable "off-target" effects of TZDs have made us rethink their role and be more cautious about the long-term benefits and risks related to their use. This review examines the most relevant work on the benefits and risks associated with TZD treatment, with a focus on the only PPARγ agonist currently available (pioglitazone), aiming to offer the reader a balanced overview about the current and future role of TZDs in the management of insulin-resistant states and T2DM.

Outcomes and lessons from the PROactive study

Beyond improvement of glucose control, thiazolidinediones exert pleiotropic effects, which may contribute to some cardiovascular protection. PROactive ("PROspective pioglitAzone Clinical Trial In macroVascular Events") has provided valuable, although controversial, information on the impact of pioglitazone on cardiovascular outcomes in a high-risk population of patients with type 2 diabetes and established macrovascular disease. Since 2005, there has been much debate on the relative value of the statistically non-significant 10% reduction in the quite challenging primary composite endpoint (combining cardiovascular disease-driven and procedural events in all vascular beds) versus the statistically significant 16% decrease in the more robust and conventional main secondary endpoint (all-cause mortality, myocardial infarction, and stroke) observed with pioglitazone. Revisiting PROactive deserves much interest following the report of inconclusive results on cardiovascular efficacy and safety of rosiglitazone in RECORD, the withdrawal (limitation) of rosiglitazone because of cardiovascular safety concern, the recent publication of a statement positioning pioglitazone in type 2 diabetes and the near availability of cheaper generics of pioglitazone. Although subanalyses may have more limited value from a statistical viewpoint, they nonetheless can provide valuable information on the drug efficacy/safety profile and clinical insights into which patients might benefit most (in terms of cardiovascular outcomes) from pioglitazone therapy.

Peroxisome proliferator-activated receptor (PPAR α/γ) agonists as a potential target to reduce cardiovascular risk in diabetes

The disappointing results of glucose lowering studies have highlighted the ongoing need to develop new therapeutic strategies to reduce cardiovascular risk in patients with type 2 diabetes. The presence of a range of metabolic abnormalities in diabetic patients presents a number of potential targets for therapeutic intervention. While modulation of peroxisome proliferator activated receptors (PPARs) represents an attractive approach, the results of studies of pharmacological agonists have been variable. The findings of these studies and rationale for development of dual PPAR-α/γ agonists will be reviewed.

The Development of INT131 as a Selective PPARgamma Modulator: Approach to a Safer Insulin Sensitizer

INT131 (formerly T0903131, T131, AMG131) is a potent non-thiazolidinedione (TZD) selective peroxisome proliferator-activated receptor γ modulator (SPPARM) currently in Phase 2 clinical trials for treatment of type-2 diabetes mellitus (T2DM). This new chemical entity represents a second generation SPPARM approach developed after the first generation PPARγ full agonists to address their inherent limitations. INT131 was specifically and carefully designed using preclinical models to exhibit a biological profile of strong efficacy with de minimis side effects compared to PPARγ full agonists. As a potent PPARγ modulator, INT131 binds to PPARγ with high affinity. In pharmacology models of diabetes and in early clinical studies, it achieved a high level of efficacy in terms of antidiabetic actions such as insulin sensitization and glucose and insulin lowering, but had little activity in terms of other, undesired, effects associated with TZD PPARγ full agonists such as edema and adipogenesis. Ongoing clinical development is directed at translating these findings into establishing a novel and effective treatment for T2DM patients with an improved safety profile in relation to that currently available.

Troglitazone induces cytotoxicity in part by promoting the degradation of peroxisome proliferator-activated receptor γ co-activator-1α protein

BACKGROUND AND PURPOSE

Troglitazone (Tro), rosiglitazone (Rosi) and pioglitazone (Pio) are anti-diabetic thiazolidinediones that function as ligands for peroxisome proliferator-activated receptor γ (PPARγ); however, Tro has been withdrawn from the market due to liver toxicity issues. Mitochondrial dysfunction induced by Tro has been suggested to be an important mechanism behind its cytotoxicity. Constitutively active nuclear hormone receptors, oestrogen-related receptor α and γ are thought to regulate mitochondrial mass and oxidative phosphorylation together with their co-activators PPARγ co-activator-1α and -1β (PGC-1α and PGC-1β). Hence, in this study, we investigated whether Tro affects the expression and activity levels of these regulators.

EXPERIMENTAL APPROACH

Cellular viability was measured by an ATP-based assay. Mitochondrial mass and reactive oxygen species (ROS) were quantified by two different fluorogenic probes. Apoptosis was measured by an Annexin-V-based kit. Gene expression at the levels of mRNA and protein was measured by quantitative RT-PCR and Western analysis. Over-expression of PGC-1α was mediated by an adenovirus.

KEY RESULTS

Tro, but not Rosi or Pio, selectively stimulated PGC-1α protein degradation. As a result, Tro reduced mitochondrial mass, and superoxide dismutases 1 and 2 expressions, but induced ROS to initiate apoptosis. Using a ubiquitin-proteasome inhibitor MG132, it was established that blocking PGC-1α degradation partially suppressed the reduction of mitochondrial mass. Importantly, over-expressing PGC-1α partially restored the Tro-suppressed mitochondrial mass and attenuated the cytotoxic effects of Tro.

CONCLUSIONS AND IMPLICATIONS

Collectively, these results suggest that PGC-1α degradation is an important mechanism behind the cytotoxic effects of Tro in the liver.

Pioglitazone for the treatment of type 2 diabetes in patients inadequately controlled on insulin

Insulin resistance and impaired beta-cell function are primary defects that occur early in the course of development of type 2 diabetes. Insulin resistance leads to hyperinsulinemia in order to maintain normal glucose tolerance. In most cases of type 2 diabetes, beta-cell dysfunction develops subsequent to the development of insulin resistance, and it is not until such beta-cell dysfunction develops that any abnormality in glucose tolerance is seen. Insulin resistance is a primary defect in type 2 diabetes. The risk of coronary heart disease is significantly increased in patients with type 2 diabetes. Cardiovascular disease causes 80% of all diabetic mortality, and in 75% of those cases, it is a result of coronary atherosclerosis. These points provide a rationale for early and aggressive management of cardiovascular risk in patients with diabetes. Thiazolidinediones represent an effective tool for targeting some features of this increased risk as they decrease insulin resistance and can prevent and/or delay diabetes progression.

Concomitant therapy with pioglitazone and insulin for the treatment of type 2 diabetes

To prevent hyperinsulinemia, which may cause atherosclerosis, thiazolidinediones (TZDs), also known as insulin sensitizers, are often added to the therapeutic regimen of patients with type 2 diabetes who are receiving insulin. The combination of insulin with pioglitazone, a TZD, reduces glycoated hemoglobin (HbA(1c)) by 0.6%-2.1%. The higher the HbA(1c) baseline the larger the therapeutic reduction of HbA(1c). This combination therapy has been shown to be beneficial even in lean Japanese patients with diabetes. It should be noted that such combination therapy is much more useful when the main clinical aim is lowering not postprandial, but fasting and nocturnal glycemia. The glycemic-lowering effects of pioglitazone alone occur slowly, whereas the addition of insulin to pioglitazone often shows a dramatic glucose-lowering effect. Thus, such combination therapy increases the possibility of frequent hypoglycemia within 1 to 2 months of combining the drugs. Severe hypoglycemia in patients using this therapy is rare. Patients treated with combination therapy who show a predominant reduction of glycemia often have severe edema; in 10%-20% of patients, combination therapy leads to drug-related congestive heart failure (CHF). However, this phenomenon is usually weakened if low doses of pioglitazone which are added to insulin therapy (ie, 15 mg/day or even 7.5 mg/day for women). It is well known that pioglitazone has an anti-atherosclerotic effect, although it is unclear if hyperinsulinemia induces atherogenic changes, either directly or indirectly, by the promotion of obesity. Until now, we have not confirmed whether the anti-atherosclerotic effects of pioglitazone exceed the supposed disadvantageous action of insulin when used in combination therapy. The addition of pioglitazone tends to reduce daily insulin dosages, but study findings have not been consistent. Improvement of lipid profiles has also been weak with this combination therapy. Long-term trials are needed before any conclusions can be reached concerning atherogenic effects of treatment for type 2 diabetes. Combination therapy of even small doses of pioglitazone with insulin should be primarily used for patients who achieve insufficient reduction in glycemia with insulin monotherapy.

Selective peroxisome proliferator-activated receptor gamma (PPARgamma) modulation as a strategy for safer therapeutic PPARgamma activation

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a clinically validated target for treatment of insulin resistance. PPARgamma activation by full agonists such as thiazolidinediones has shown potent and durable glucose-lowering activity in patients with type 2 diabetes without the concern for hypoglycemia or gastrointestinal toxicities associated with some other medications used to treat this disease. However, thiazolidinediones are linked to safety and tolerability issues such as weight gain, fluid retention, edema, congestive heart failure, and bone fracture. Distinctive properties of PPARgamma provide the opportunity for selective modulation of the receptor such that desirable therapeutic effects may be attained without the unwanted effects of full activation. PPARgamma is a nuclear receptor that forms a complex with coreceptor RXR and a cell type- and cell state-specific array of coregulators to control gene transcription. PPARgamma affinity for these components, and hence transcriptional response, is determined by the conformational changes induced by ligand binding within a complex pocket with multiple interaction points. This molecular mechanism thereby offers the opportunity for selective modulation. A desirable selective PPARgamma modulator profile would include high-affinity interaction with the PPARgamma-binding pocket in a manner that leads to retention of the insulin-sensitizing activity that is characteristic of full agonists as well as mitigation of the effects leading to increased adiposity, fluid retention, congestive heart failure, and bone fracture. Examples of endogenous and synthetic selective PPARgamma modulator (SPPARM) ligands have been identified. SPPARM drug candidates are being tested clinically and provide support for this strategy.

Anti-allergic function and regulatory mechanisms of KR62980 in allergen-induced airway inflammation

The ligand-activated transcription factor, peroxisome proliferator-activated receptor (PPAR)gamma, and its ligands inhibit pro-inflammatory cytokine production by immune cells, thus exerting anti-inflammatory activity. As a non-thiazolidinedione PPARgamma ligand, KR62980 has anti-diabetic and anti-adipogenic activities, but its anti-inflammatory function has yet to be characterized. In this study, we investigated the functions and mechanisms of KR62980 in the activation and differentiation of CD4+ T helper (Th) cells by comparing its effects with those of a thiazolidinedione PPARgamma ligand, rosiglitazone. KR62980 dose-dependently and significantly suppressed TCR-triggered Th cell proliferation by suppressing IL-2/IL-2Ralpha-mediated signaling. Both KR62980 and rosiglitazone suppressed IFNgamma production in a dose-dependent manner, whereas IL-4 gene expression was specifically suppressed by only KR62980. In addition, sustained KR62980 treatment diminished Th2 cytokine production by inhibiting c-Maf expression. In vivo administration of KR62980 in a model of allergic asthma significantly attenuated eotaxin-induced eosinophil infiltration, allergic cytokine production and collagen deposition in the lung. KR62980 also decreased goblet cell hyperplasia in the airway and mucous cell metaplasia in nasal epithelium, concurrent with decreases of allergic Th2 cytokines and IL-17 in the draining lymph node. In conclusion, a novel PPARgamma ligand, KR62980, suppresses in vitro Th2 cell differentiation and attenuates in vivo OVA-induced airway inflammation, suggesting a beneficial role for KR62980 in the treatment of allergic asthma and allergic rhinitis.

Cardiovascular risk of rosiglitazone: another perspective

Rosiglitazone is an effective therapy for type 2 diabetes although concerns have grown about the incidence of oedema and cardiovascular adverse events in patients treated with the drug. The following review was conducted to evaluate further and complement the evidence linking rosiglitazone with an increased risk for cardiovascular adverse events by examining trials and case reports not included in recent meta-analyses. Rosiglitazone-related publications describing case reports and prospective and retrospective cohort analyses were identified using MEDLINE and EMBASE, from July 1999 to July 2007. Relevant reports cited in these publications were also obtained. A recently-published meta-analysis and a double-blind, randomized, placebo-controlled trial were also reviewed. This review of 20 case reports and 10 uncontrolled studies supports the need for added vigilance when prescribing rosiglitazone to patients for the treatment of type 2 diabetes who may be at risk for congestive heart failure. Clinical data from numerous case reports and uncontrolled studies suggested that patients receiving rosiglitazone should be monitored for the development of weight gain or oedema. Prudence should be observed in patients with a history or risk factors for congestive heart failure as they may be poor candidates for rosiglitazone therapy.

Late-Onset Rosiglitazone-Associated Acute Liver Failure in a Patient with Hodgkin's Lymphoma

Objective:

To report a case of rosiglilazone-associated hepatotoxicity in a patient with Hodgkin's lymphoma.

Case Summary:

A 52-year-old man presented with low-grade fever and fatigue that had been present for 4 months. He had been receiving insulin for 5 years and rosiglitazone 4 mg/day for 11 months for control of type 2 diabetes; he was receiving no other drug therapy. During hospitalization, hepatotoxicity was shown, with abnormal liver function test results including alanine aminotransferase 488 U/L, aspartate aminotransferase 344 U/L, alkaline phosphatase B32 U/L, total bilirubin 4.61 mg/dL, and direct bilirubin 3.63 mg/dL. Rosiglitazone was discontinued after further elevation of bilirubin (total 14.67 mg/dL, direct 12.10 mg/dL) occurred. Other causes for hepatotoxicity were ruled out, Hodgkin's lymphoma was diagnosed during the workup; however, liver imaging and biopsy also excluded this as the direct cause of acute liver failure. Despite discontinuation of rosiglitazone, the bilirubin level continued to increase to 49.29 mg/dL (direct >20 mg/dL). The patient died 3 months after admission.

Discussion:

Rosiglitazone maleate is a thiazolidinedione approved for treatment of type 2 diabetes mellitus. The first member of this drug class, troglitazone, was withdrawn from the market due to reports of acute liver failure. Rosiglitazone has been shown to be much safer than troglitazone, despite some reported cases of early-onset nonfatal hepatotoxicity. Use of the Naranjo probability scale indicated that rosiglitazone was the probable cause of acute liver failure in our patient.

Conclusions:

We conclude that rosiglitazone may be associated with late-onset acute liver failure. Clinicians should be aware of such a complication and monitor liver function in patients receiving the drug.

Rosiglitazone-induced anasarca without heart failure: capillary leakage?

Severity of thiazolidinedione (Rosiglitazone)-induced fluid retention is linked almost exclusively to cardiac decompensation. We here report a 68-year old female with type 2 diabetes mellitus, in whom a life-threatening (anasarca type) acute pulmonary edema, induced by rosiglitazone plus insulin therapy, occurred without any evidence of left ventricular systolic or diastolic dysfunction. It seems that thiazolidinedione-induced severe edema does not have to be the result of acute congestive heart failure. These agents have been shown to increase vascular permeability in experimental models. Thus, the recommendation of only cardiac monitoring in pulmonary edema, associated with thiazolidinediones, should be reconsidered.

Why insulin sensitizers but not secretagogues should be retained when initiating insulin in type 2 diabetes

The stringent targets set for HbA(1c) levels in type 2 diabetes are currently achieved by fewer than half the patients in the United States. Failure to manage hyperglycaemia in the early stages of disease results in progressive loss of beta-cell function, which ultimately necessitates the initiation of insulin therapy. At this point, choices have to be made on whether to continue oral anti-diabetic drug therapy and, if so, with which agent(s). Historically, sulfonylureas have been the mainstay of oral anti-diabetic drug therapy; however, their long-term efficacy in patients with depleted beta-cell capacity is doubtful, and other classes of oral anti-diabetic drugs, notably the insulin sensitizers, may prove more reliable. These agents (metformin and thiazolidinediones) appear to provide various benefits over and above sustained glycaemic control, which may variably include reduced loss of beta-cell function as well as improvements to cardiovascular risk factors, morbidity, and mortality. Metformin also limits weight gain associated with insulin therapy. This manuscript presents the case that when insulin therapy is initiated it should be tailored to individual needs through combination with one or more insulin sensitizers rather than a secretagogue.

Dioscorea as the principal herb of Die-Huang-Wan, a widely used herbal mixture in China, for improvement of insulin resistance in fructose-rich chow-fed rats

The present study was designed to clarify the principal herb responsible for the improvement of insulin resistance produced by Die-Huang-Wan, a mixture of six herbs, in rats fed with fructose-rich chow for 4 weeks. A decrease in plasma glucose was observed in fructose-rich chow-fed rats received an oral administration of Die-Huang-Wan at 26 mg/kg for 60 min but it disappeared with the deletion of dioscorea (Dioscoreae rhizoma) while this action was not modified by the deletion of other five herbs. The decrease of plasma glucose in fructose-rich chow-fed rats produced by dioscorea was similar to that treated with Die-Huang-Wan at same dosing; while the other five herbs failed to produce same influence. Similar to the effect of Die-Huang-Wan, dioscorea improved the fructose-induced decrement of insulin-stimulated glucose disposal rate after 3 days of treatment. Also, oral administration of dioscorea at effective dose (4.2 mg/kg per administration, three times daily) into streptozotocin-induced diabetic rats for 10 days increased the response to exogenous insulin, approaching to that induced by Die-Huang-Wan in same treatment. However, these effects failed to induce in the dioscorea-deleted formula of Die-Huang-Wan or other five herbs of this mixture. These results suggest that dioscorea is the major herb for the improvement of insulin sensitivity produced by Die-Huang-Wan. This can be applied to use as an adjuvant for subjects who need to increase insulin sensitivity.

Effects of Astragalus polysaccharides on proliferation and differentiation of 3T3-L1 preadipocytes

OBJECTIVE

To observe the effects of Astragalus polysaccharides (APS) on the proliferation and differentiation of 3T3-L1 preadipocytes and to elucidate its possible mechanism.

METHODS

The proliferation of 3T3-L1 preadipocytes was detected by XTT method. Lipid droplets accumulated in cytoplasm of the differentiated preadipocytes were observed by using red O staining and quantified by colorimetry. The expressions of peroxisome proliferation activated receptor gamma (PPAR gamma) and CAAT/enhancer binding protein (C/EBP alpha) mRNAs and proteins were detected by real-time polymerase chain reaction (RT-PCR) and Western blotting respectively.

RESULTS

APS at different concentrations (0.025-0.8 g/L) affected 3T3-L1 preadipocyte proliferation and differentiation dose-dependently. 3T3-L1 preadipocytes treated with 0.4 g/L APS had lots of lipid droplets in the cytoplasma, which were similar to cells treated with rosiglitazone (ROS). APS significantly increased the mRNA and protein expressions of PPAR gamma and C/EBP alpha (P<0.05, P<0.01, compared with the normal control group) in the course of 3T3-LI preadipocyte differentiation.

CONCLUSION

APS can promote the proliferation of 3T3-L1 preadipocytes, enhance the accumulation of lipid drops, and increase the terminal differentiation of preadipocytes, which may be associated with its effects in increasing the expressions of PPAR gamma and C/EBP alpha mRNAs and proteins. The study suggests that APS has potential in the treatment of metabolic syndrome.

Effect of pioglitazone in combination with insulin therapy on glycaemic control, insulin dose requirement and lipid profile in patients with type 2 diabetes previously poorly controlled with combination therapy

AIM

The aim of this randomized placebo-controlled study was to evaluate the safety and efficacy of pioglitazone administered alone or in combination with metformin in reducing insulin dosage requirements for improved glycaemic control in patients with type 2 diabetes previously poorly controlled with combination therapy.

METHODS

In this multicentre, double-blind study, 222 patients with haemoglobin A1c (HbA(1c))>8.0% at screening treated with combination therapy initially were given titrated insulin therapy (to fasting plasma glucose <140 mg/dl) and then were randomly assigned to 20-week treatment with pioglitazone or placebo in combination with insulin, with or without concurrent metformin therapy. More than 98% of patients were taking metformin prior to and during the study.

RESULTS

Pioglitazone significantly reduced (p < 0.05) insulin dose requirements 2 weeks after treatment initiation. At study end relative to baseline, pioglitazone reduced daily insulin dosages by 12.0 units (p < 0.001), a 21.5% (12.0/55.8 units at baseline) group mean average reduction. Relative to placebo, pioglitazone reduced daily insulin dosages by 12.7 units [95% confidence interval [CI]: -17.5, -8.0], while improving mean HbA(1c) levels [adjusted mean HbA(1c) change: pioglitazone, -1.6% vs. placebo, -1.4% (not statistically different)]. Pioglitazone also significantly increased high-density lipoprotein cholesterol levels [adjusted mean difference: +4.5 (95% CI: 2.6-6.5) mg/dl], decreased triglyceride levels [-43.9 (-69.2, -18.6) mg/dl], shifted low-density lipoprotein (LDL) particle concentrations from small [pattern B, -13.6% (-17.7%, -9.5%)] to large [pattern A, +15.1% (10.8%, 19.5%)] and increased mean LDL particle size [+3.8 (2.6, 4.9) A]. More pioglitazone-treated patients experienced oedema (9.0 vs. 4.5%) and weight gain (9.1 vs. 2.7%) than placebo patients.

CONCLUSIONS

Pioglitazone in combination with insulin therapy improved glycaemic control, reduced insulin dose requirements and improved lipid profiles in patients with type 2 diabetes previously poorly controlled with combination therapy.

Soy protein and isoflavones influence adiposity and development of metabolic syndrome in the obese male ZDF rat

BACKGROUND/AIMS

Previously, we demonstrated that soy protein ameliorates the diabetic phenotype in several rodent models of obesity and metabolic syndrome (MS). This study was designed to further elucidate factors related to adiposity, glycemic control, and renal function in male Zucker Diabetic Fatty (ZDF/Lepr(fa)) rats.

METHODS

Animals were randomly assigned to one of four diets: control, casein (C); low isoflavone (LIS) soy protein; high isoflavone (HIS) soy protein, or casein + rosiglitazone (CR) for 11 weeks. At sacrifice, physiological, biochemical, and molecular parameters were determined.

RESULTS

Body weight and total adiposity were higher in LIS and CR diet groups despite lower food intake. Additionally, these animals exhibited differential regulation of adipose-specific proteins (PPAR-gamma and GLUT4) and enzyme activity (FAS and GPDH). HIS-fed animals had reduced total and liver adiposity. Glycemic control was prolonged in both soy-based and rosiglitazone (RGZ) groups. Renal dysfunction was significantly reduced in soy-fed and RGZ-treated rodents as demonstrated by lower levels of proteinuria and dilated tubules with proteinaceous casts.

CONCLUSION

Collectively, these data provide evidence that soy protein with low or high isoflavone content may have therapeutic significance in reducing severity of diabetes, MS, and renal disease as demonstrated in this preclinical model.

Pharmacokinetic interactions with thiazolidinediones

Type 2 diabetes mellitus is a complex disease combining defects in insulin secretion and insulin action. New compounds called thiazolidinediones or glitazones have been developed for reducing insulin resistance. After the withdrawal of troglitazone because of liver toxicity, two compounds are currently used in clinical practice, rosiglitazone and pioglitazone. These compounds are generally used in combination with other pharmacological agents. Because they are metabolised via cytochrome P450 (CYP), glitazones are exposed to numerous pharmacokinetic interactions. CYP2C8 and CYP3A4 are the main isoenzymes catalysing biotransformation of pioglitazone (as with troglitazone), whereas rosiglitazone is metabolised by CYP2C9 and CYP2C8. For both rosiglitazone and pioglitazone, the most relevant interactions have been described in healthy volunteers with rifampicin (rifampin), which results in a significant decrease of area under the plasma concentration-time curve [AUC] (54-65% for rosiglitazone, p<0.001; 54% for pioglitazone, p<0.001), and with gemfibrozil, which results in a significant increase of AUC (130% for rosiglitazone, p<0.001; 220-240% for pioglitazone, p<0.001). The relevance of such drug-drug interactions in patients with type 2 diabetes remains to be evaluated. However, in the absence of clinical data, it is prudent to reduce the dosage of each glitazone by half in patients treated with gemfibrozil. Conversely, rosiglitazone and pioglitazone do not seem to significantly affect the pharmacokinetics of other compounds. Although some food components have also been shown to potentially interfere with drugs metabolised with the CYP system, no published study deals specifically with these possible CYP-mediated food-drug interactions with glitazones.

Drug-Induced Cardiovascular Disorders

As the variety and range of pharmaceutical agents available to the medical profession continues to expand, one unavoidable effect will be an increase in drug-induced disease, including cardiovascular disorders. However, given the high rates of cardiovascular disease and prevalence of recognised cardiovascular risk factors in the population, it is sometimes impossible to conclusively attribute any individual patients' ill health to one particular drug. As a result, the relationship between drugs and cardiovascular disease is often difficult to quantify. This review discusses specific forms of drug-induced cardiovascular disease such as heart failure, left ventricular systolic dysfunction, hypertension and arrhythmia. Suspected culprit drugs for all disorders are highlighted. Specific attention is given to certain drug groups with a strong association with one or more forms of cardiovascular disease: these include anthracyclines, antipsychotics, NSAIDs and cyclo-oxygenase 2 inhibitors. Additionally, advice is offered on how physicians might distinguish drug-induced cardiovascular disorders from other aetiologies.

Drug interactions of clinical importance with antihyperglycaemic agents: an update

Because management of type 2 diabetes mellitus usually involves combined pharmacological therapy to obtain adequate glucose control and treatment of concurrent pathologies (especially dyslipidaemia and arterial hypertension), drug-drug interactions must be carefully considered with antihyperglycaemic drugs. Additive glucose-lowering effects have been extensively reported when combining sulphonylureas (or the new insulin secretagogues, meglitinide derivatives, i.e. nateglinide and repaglinide) with metformin, sulphonylureas (or meglitinide derivatives) with thiazolidinediones (also called glitazones) and the biguanide compound metformin with thiazolidinediones. Interest in combining alpha-glucosidase inhibitors with either sulphonylureas (or meglitinide derivatives), metformin or thiazolidinediones has also been demonstrated. These combinations result in lower glycosylated haemoglobin (HbA(1c)), fasting glucose and postprandial glucose levels than with either monotherapy. Even if modest pharmacokinetic interferences have been reported with some combinations, they do not appear to have important clinical consequences. No significant adverse effects, except a higher risk of hypoglycaemic episodes that may be attributed to better glycaemic control, occur with any combination. Challenging the classical dual therapy with sulphonylurea plus metformin, there is a recent trend to use alternative dual combinations (sulphonylurea plus thiazolidinedione or metformin plus thiazolidinedione). In addition, triple therapy with the addition of a thiazolidinedione to the metformin-sulphonylurea combination has been recently evaluated and allows glucose targets to be reached before insulin therapy is considered. This triple therapy appears to be safe, with no deleterious drug-drug interactions being reported so far.Potential interferences may also occur between glucose-lowering agents and other drugs, and such drug-drug interactions may have important clinical implications. Relevant pharmacological agents are those that are widely coadministered in diabetic patients (e.g. lipid-lowering agents, antihypertensive agents); those that have a narrow efficacy/toxicity ratio (e.g. digoxin, warfarin); or those that are known to induce (rifampicin [rifampin]) or inhibit (fluconazole) the cytochrome P450 (CYP) system. Metformin is currently a key compound in the pharmacological management of type 2 diabetes, used either alone or in combination with other antihyperglycaemics. There are no clinically relevant metabolic interactions with metformin, because this compound is not metabolised and does not inhibit the metabolism of other drugs. In contrast, sulphonylureas, meglitinide derivatives and thiazolidinediones are extensively metabolised in the liver via the CYP system and thus, may be subject to drug-drug metabolic interactions. Many HMG-CoA reductase inhibitors (statins) are also metabolised via the CYP system. Even if modest pharmacokinetic interactions may occur, it is not clear whether drug-drug interactions between oral antihyperglycaemic agents and statins may have clinical consequences regarding both efficacy and safety. In contrast, a marked pharmacokinetic interference has been reported between gemfibrozil and repaglinide and, to a lesser extent, between gemfibrozil and rosiglitazone. This leads to a drastic increase in plasma concentrations of each antihyperglycaemic agent when they are coadministered with the fibric acid derivative, and an increased risk of adverse effects. Some antihypertensive agents may favour hypoglycaemic episodes when co-prescribed with sulphonylureas or meglitinide derivatives, especially ACE inhibitors, but this effect seems to result from a pharmacodynamic drug-drug interaction rather than from a pharmacokinetic drug-drug interaction. No, or only modest, interferences have been described with glucose-lowering agents and other pharmacological compounds such as digoxin or warfarin. The effects of inducers or inhibitors of CYP isoenzymes on the metabolism and pharmacokinetics of the glucose-lowering agents of each pharmacological class has been tested. Significantly increased (with CYP inhibitors) or decreased (with CYP inducers) plasma levels of sulphonylureas, meglitinide derivatives and thiazolidinediones have been reported in healthy volunteers, and these pharmacokinetic changes may lead to enhanced or reduced glucose-lowering action, and thus hypoglycaemia or worsening of metabolic control, respectively. In addition, some case reports have evidenced potential drug-drug interactions with various antihyperglycaemic agents that are usually associated with a higher risk of hypoglycaemia.

The insulin sensitiser pioglitazone does not influence skin microcirculatory function in patients with type 2 diabetes treated with insulin

AIMS/HYPOTHESIS

Insulin resistance is associated with abnormal microvascular function. Treatment with insulin sensitisers may provoke oedema, suggesting microvascular effects. The mechanisms underlying the peripheral oedema observed during glucose-lowering treatment with thiazolidinediones are unclear. Therefore we examined the effect of pioglitazone on microvascular variables involved in oedema formation.

METHODS

Subjects (40-80 years) with type 2 diabetes and on insulin were randomised to 9 weeks of pioglitazone therapy (30 mg/day; n=14) or placebo (n=15). The following assessments were performed at baseline and 9 weeks: microvascular filtration capacity; isovolumetric venous pressure; capillary pressure; capillary recruitment following venous or arterial occlusion; postural vasoconstriction; and maximum blood flow. A number of haematological variables were also measured including vascular endothelium growth factor (VEGF), IL-6 and C-reactive protein (CRP).

RESULTS

Pioglitazone did not significantly influence any microcirculatory variable as compared with placebo (analysis of covariance [ANCOVA] for microvascular filtration capacity for the two groups, p=0.26). Mean VEGF increased with pioglitazone (61.1 pg/ml), but not significantly more than placebo (9.76 pg/ml, p=0.94). HbA(1c) levels and the inflammatory markers IL-6 and CRP decreased with pioglitazone compared with placebo (ANCOVA: p=0.009, p=0.001 and p=0.004, respectively).

CONCLUSIONS/INTERPRETATION

Pioglitazone improved glycaemic control and inflammatory markers over 9 weeks but had no effect on microcirculatory variables associated with oedema or insulin resistance in type 2 diabetic patients treated with insulin.

Addition of pioglitazone to stable insulin therapy in patients with poorly controlled type 2 diabetes: results of a double-blind, multicentre, randomized study

AIM

To determine the effects of pioglitazone treatment combined with insulin on glucose and lipid metabolism in patients with type 2 diabetes.

METHODS

In a multicentre, double-blind study, 690 patients [body mass index, 33.19 kg/m2 +/- 5.47; haemoglobin A1c (A1C), 9.78 +/- 1.51; mean duration, 12.9 years] with diabetes poorly controlled with a stable insulin dose (> 30 U/day for > or =30 days) were randomly allocated to pioglitazone 30 or 45 mg once daily for 24 weeks.

RESULTS

In the pioglitazone 30- and 45-mg groups, respectively, 71 and 70% of patients completed the study. At 24 weeks, statistically significant, dose-dependent mean decreases from baseline were seen in the pioglitazone 30- and 45-mg groups for A1C (-1.17 and -1.46%, respectively) and fasting plasma glucose (-31.9 and -45.8 mg/dl, respectively). Insulin dosage also decreased significantly (-4.5 and -7.3 U, respectively; p < or = 0.05) from baseline. Decreases in triglycerides [pioglitazone 45 mg: -5.9% (p < or = 0.05)], very low-density lipoprotein cholesterol [pioglitazone 45 mg: -6.2% (p < or = 0.05)] and free fatty acids [-0.94 (p < or = 0.05) and -2.13 (p < 0.0001) mg/dl, respectively] and increases in high-density lipoprotein cholesterol (9.7 and 13.0%, respectively; p < 0.0001) also were observed from baseline. Small but significant increases in total and low-density lipoprotein cholesterol (p < 0.01) from baseline were observed. Mean weight gain was 2.9 and 3.4 kg in the respective groups; lower limb oedema was reported in 13 and 12% of patients, respectively. The incidences of oedema, weight gain and heart failure were not higher than anticipated in this population. No evidence of hepatotoxicity or clinically significant elevations in liver function test parameters was seen.

CONCLUSIONS

In patients with poorly controlled type 2 diabetes, addition of pioglitazone to insulin significantly improved glycaemic control, had a positive effect on important components of the lipid profile in a dose-dependent manner and was generally well tolerated.