New Drugs for the Treatment of Diabetes Mellitus

Initial combination therapy with alogliptin and pioglitazone in drug-naïve patients with type 2 diabetes

OBJECTIVE

To assess the efficacy and tolerability of alogliptin plus pioglitazone for initial combination therapy in drug-naïve type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

This 26-week, double-blind, parallel-group study randomized 655 patients with inadequately controlled type 2 diabetes to four arms: 25 mg alogliptin (A25) q.d. monotherapy, 30 mg pioglitazone (P30) q.d. monotherapy, or 12.5 (A12.5) or 25 mg alogliptin q.d. plus pioglitazone (P30) q.d. combination therapy. Primary efficacy was A1C change from baseline with the high-dose combination (A25+P30) versus each monotherapy.

RESULTS

Combination therapy with A25+P30 resulted in greater reductions in A1C (-1.7±0.1% from an 8.8% mean baseline) vs. A25 (-1.0±0.1%, P<0.001) or P30 (-1.2±0.1%, P<0.001) and in fasting plasma glucose (-2.8±0.2 mmol/l) vs. A25 (-1.4±0.2 mmol/l, P<0.001) or P30 (-2.1±0.2 mmol/l, P=0.006). The A25+P30 safety profile was consistent with those of its component monotherapies.

CONCLUSIONS

Alogliptin plus pioglitazone combination treatment appears to be an efficacious initial therapeutic option for type 2 diabetes.

Blood glucose control and coronary heart disease

Epidemiologic data support the hypothesis of a direct and independent relationship between hyperglycemia and cardiovascular disease. The lack of a clear-cut threshold value in diabetic patients, and the persistence of the relationship in nondiabetic population as well, suggest that glycemia is a continuous variable, similarly to other cardiovascular risk factors. Moreover, increased plasma glucose levels contribute to cardiovascular risk by activating multiple atherogenic mechanisms. In spite of evident plausibility for hyperglycemia as a cardiovascular risk factor per se, intervention data remain controversial. Results of recent large-scale intervention trials, such as ACCORD, ADVANCE, and VADT, seem to undermine the concept that tight glycemic control confers some protection against cardiovascular disease in patients with type 2 diabetes, while maintenance of near-normal glycemic control from earlier stage of the disease and during acute coronary events seems to be more beneficial. However, individualized therapies remain the cornerstone of strategies aimed to reduce cardiovascular risk associated to hyperglycemia.

Randomized comparison of the effects of rosiglitazone vs. placebo on peak integrated cardiovascular performance, cardiac structure, and function

AIMS

To assess the effect of rosiglitazone on cardiovascular performance and cardiac function.

METHODS AND RESULTS

One hundred and fifty type 2 diabetes patients with cardiovascular disease (CVD) or ≥ 1 other CVD risk factor were randomized to receive rosiglitazone vs. placebo for 6 months. The primary outcome was peak oxygen uptake indexed to fat-free mass (VO(2peak)-FFM) during maximum exercise. A subset of 102 subjects underwent cardiac magnetic resonance imaging (cMRI). On hundred and eight subjects completed the study, including 75 completing the cMRI substudy. No significant differences were observed in mean VO(2peak)-FFM between rosiglitazone and placebo (26.1 ± 7.0 vs. 27.6 ± 6.6 mL/kg-FFM/min; P = 0.26). Compared with placebo, the rosiglitazone group had lower hematocrit (38 vs. 41%; P < 0.001) and more peripheral oedema (53.7 vs. 33.3%; P = 0.03). In the cMRI substudy, compared with placebo, the rosiglitazone group had larger end-diastolic volume (128.1 vs. 112.0 mL; P = 0.01) and stroke volume (83.7 vs. 72.9 mL; P = 0.01), and a trend toward increased peak ventricular filling rate (79.4 vs. 60.5; P = 0.07).

CONCLUSION

Rosiglitazone increased peripheral oedema but had no pernicious effects on cardiovascular performance or cardiac function, with modest improvement in selected cMRI measures. Changes in indirect markers of plasma volume suggest expansion with rosiglitazone.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT00424762.

Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes

BACKGROUND

In a previous pooled analysis of 12 double-blind clinical studies that included data on 6,139 patients with type 2 diabetes, treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to be generally well tolerated compared with treatment with control agents. As clinical development of sitagliptin continues, additional studies have been completed, and more patients have been exposed to sitagliptin. The purpose of the present analysis is to update the safety and tolerability assessment of sitagliptin by pooling data from 19 double-blind clinical studies.

METHODS

The present analysis included data from 10,246 patients with type 2 diabetes who received either sitagliptin 100 mg/day (N = 5,429; sitagliptin group) or a comparator agent (placebo or an active comparator) (N = 4,817; non-exposed group). The 19 studies from which this pooled population was drawn represent the double-blind, randomized studies that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years and for which results were available as of July 2009. These 19 studies assessed sitagliptin taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin). Patients in the non-exposed group were taking placebo, metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin. The analysis used patient-level data from each study to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events.

RESULTS

Summary measures of overall adverse events were similar in the sitagliptin and non-exposed groups, except for an increased incidence of drug-related adverse events in the non-exposed group. Incidence rates of specific adverse events were also generally similar between the two groups, except for increased incidence rates of hypoglycemia, related to the greater use of a sulfonylurea, and diarrhea, related to the greater use of metformin, in the non-exposed group and constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events.

CONCLUSIONS

In this updated pooled safety analysis of data from 10,246 patients with type 2 diabetes, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.

Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes

BACKGROUND

In a previous pooled analysis of 12 double-blind clinical studies that included data on 6,139 patients with type 2 diabetes, treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to be generally well tolerated compared with treatment with control agents. As clinical development of sitagliptin continues, additional studies have been completed, and more patients have been exposed to sitagliptin. The purpose of the present analysis is to update the safety and tolerability assessment of sitagliptin by pooling data from 19 double-blind clinical studies.

METHODS

The present analysis included data from 10,246 patients with type 2 diabetes who received either sitagliptin 100 mg/day (N = 5,429; sitagliptin group) or a comparator agent (placebo or an active comparator) (N = 4,817; non-exposed group). The 19 studies from which this pooled population was drawn represent the double-blind, randomized studies that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years and for which results were available as of July 2009. These 19 studies assessed sitagliptin taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin). Patients in the non-exposed group were taking placebo, metformin, pioglitazone, a sulfonylurea +/- metformin, insulin +/- metformin, or rosiglitazone + metformin. The analysis used patient-level data from each study to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events.

RESULTS

Summary measures of overall adverse events were similar in the sitagliptin and non-exposed groups, except for an increased incidence of drug-related adverse events in the non-exposed group. Incidence rates of specific adverse events were also generally similar between the two groups, except for increased incidence rates of hypoglycemia, related to the greater use of a sulfonylurea, and diarrhea, related to the greater use of metformin, in the non-exposed group and constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events.

CONCLUSIONS

In this updated pooled safety analysis of data from 10,246 patients with type 2 diabetes, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.

The effect of intensive glucose control on all-cause and cardiovascular mortality, myocardial infarction and stroke in persons with type 2 diabetes mellitus: a systematic review and meta-analysis

We performed a meta-analysis of studies evaluating the effect of intensive glucose control on major adverse cardiovascular events in patients with type 2 diabetes from 1990 to 2009. A search of the published literature and the Cochran Central Register for Controlled Trials was performed using pre-specified inclusion criteria consisting of randomised controlled trials evaluating intensive glycaemic control and reporting the individual endpoints of all-cause mortality, non-fatal myocardial infarction, and non-fatal stroke. Incident rate ratios for these endpoints were calculated using standard meta-analytic techniques of pooled data from eligible trials. Six reports from four randomised trials including 27,544 patients met the pre-specified inclusion criteria. Mean follow-up was 5.4 years; haemoglobin A(1C) at study end was 6.6% vs. 7.4% in patients randomised to intensive compared with conventional glucose control. Intensive glucose control did not affect the incident rate ratio for all-cause mortality (1.01, 95% confidence interval 0.86-1.18, p=0.54) or stroke (1.02, 95% confidence interval 0.88-1.20, p=0.62). However, there was a statistically significant 14% reduction in non-fatal myocardial infarction in patients randomised to intensive glucose control (0.86, 95% confidence interval 0.77-0.97, p=0.015). Although intensification of glucose control did not affect mortality or non-fatal stroke, the risk for non-fatal myocardial infarction was significantly reduced in patients with type 2 diabetes.

Potentiation by candesartan of protective effects of pioglitazone against type 2 diabetic cardiovascular and renal complications in obese mice

OBJECTIVES

The efficacy of renin-angiotensin system (RAS) blockers on type 2 diabetes and its complications remains to be defined. This study was undertaken to test the hypothesis that candesartan may enhance the protective effects of pioglitazone against type 2 diabetes.

METHODS

We compared the effects of pioglitazone, candesartan, and their combination on cardiorenal and vascular injury, diabetes, and tissue oxidative stress in obese and type 2 diabetic db/db mice, and also examined the effects of tempol, a superoxide dismutase (SOD) mimetic, on db/db mice to define the role of oxidative stress.

RESULTS

The addition of candesartan to pioglitazone significantly potentiated the suppressive effects of pioglitazone on cardiac macrophage infiltration and interstitial fibrosis, and glomerular macrophage infiltration and sclerosis in db/db mice. These benefits of the combination of pioglitazone and candesartan in db/db mice were attributed to additive attenuation of cardiorenal oxidative stress, through the attenuation of NADPH oxidase or the restoration of Cu/Zn-SOD and EC-SOD. The combination of these drugs reversed vascular endothelial dysfunction in db/db mice more than either monotherapy, by causing more phosphorylation of eNOS. Candesartan slightly augmented the improvement of glucose tolerance by pioglitazone in db/db mice, and this additive effect was mediated by more attenuation of oxidative stress.

CONCLUSIONS

Our work demonstrated that candesartan significantly potentiated the protective effects of pioglitazone against cardiorenal and vascular injury, and diabetes in obese type 2 diabetic mice. Thus, the combination of pioglitazone with candesartan is potentially a promising therapeutic strategy for type 2 diabetes.

Covalent peroxisome proliferator-activated receptor gamma adduction by nitro-fatty acids: selective ligand activity and anti-diabetic signaling actions

The peroxisome proliferator-activated receptor-gamma (PPARgamma) binds diverse ligands to transcriptionally regulate metabolism and inflammation. Activators of PPARgamma include lipids and anti-hyperglycemic drugs such as thiazolidinediones (TZDs). Recently, TZDs have raised concern after being linked with increased risk of peripheral edema, weight gain, and adverse cardiovascular events. Most reported endogenous PPARgamma ligands are intermediates of lipid metabolism and oxidation that bind PPARgamma with very low affinity. In contrast, nitro derivatives of unsaturated fatty acids (NO(2)-FA) are endogenous products of nitric oxide ((*)NO) and nitrite (NO(2)(-))-mediated redox reactions that activate PPARgamma at nanomolar concentrations. We report that NO(2)-FA act as partial agonists of PPARgamma and covalently bind PPARgamma at Cys-285 via Michael addition. NO(2)-FA show selective PPARgamma modulator characteristics by inducing coregulator protein interactions, PPARgamma-dependent expression of key target genes, and lipid accumulation is distinctively different from responses induced by the TZD rosiglitazone. Administration of this class of signaling mediators to ob/ob mice revealed that NO(2)-FA lower insulin and glucose levels without inducing adverse side effects such as the increased weight gain induced by TZDs.

UCF-101 mitigates streptozotocin-induced cardiomyocyte dysfunction: role of AMPK

Diabetic heart disease contributes to the high mortality in diabetics, although effective clinical management is lacking. The protease inhibitor 5-[5-(2-nitrophenyl) furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid (UCF-101) was reported to protect the hearts against ischemic injury. This study examined the role of UCF-101 on streptozotocin (STZ)-induced diabetic heart defect. Vehicle or UCF-101 was administrated to STZ diabetic mice, and cardiomyocyte mechanical properties were analyzed. UCF-101 reduced STZ-induced hyperglycemia and alleviated STZ-induced aberration in cardiomyocyte contractile mechanics. Diabetes dramatically decreased AMPK phosphorylation at Thr(172) of catalytic alpha-subunit, which was restored by UCF-101. Neither diabetes nor UCF-101 affected the expression of HtrA2/Omi and XIAP or caspase-3 activity. The AMPK activator resveratrol mimicked the UCF-101-induced beneficial effect against diabetic cardiac dysfunction. Mechanical properties in cardiomyocytes from the AMPK-kinase-dead (KD) mice displayed markedly impaired contractile function reminiscent of diabetes. STZ injection in AMPK-KD mice failed to elicit any additional cardiomyocyte contractile defect. UCF-101 significantly downregulated the AMPK-degrading enzymes PP2A and PP2C, the effect of which was mimicked by resveratrol. Taken together, these results indicate that UCF-101 protects against STZ-induced cardiac dysfunction, possibly through AMPK signaling.

Diabetic cardiomyopathy

Diabetic cardiomyopathy is a distinct primary disease process, independent of coronary artery disease, which leads to heart failure in diabetic patients. Epidemiological and clinical trial data have confirmed the greater incidence and prevalence of heart failure in diabetes. Novel echocardiographic and MR (magnetic resonance) techniques have enabled a more accurate means of phenotyping diabetic cardiomyopathy. Experimental models of diabetes have provided a range of novel molecular targets for this condition, but none have been substantiated in humans. Similarly, although ultrastructural pathology of the microvessels and cardiomyocytes is well described in animal models, studies in humans are small and limited to light microscopy. With regard to treatment, recent data with thiazoledinediones has generated much controversy in terms of the cardiac safety of both these and other drugs currently in use and under development. Clinical trials are urgently required to establish the efficacy of currently available agents for heart failure, as well as novel therapies in patients specifically with diabetic cardiomyopathy.

Prevention of weight gain in adult patients with type 2 diabetes treated with pioglitazone

Pioglitazone, a thiazolidinedione (TZD) commonly used to treat type 2 diabetes, is associated with weight gain. Our study was designed to examine the effectiveness of three lifestyle-treatment programs of varying intensity on prevention of pioglitazone-induced weight gain and to measure the composition of the change in body weight. Thirty-nine adult overweight and obese subjects with type 2 diabetes mellitus were all treated with pioglitazone and prospectively randomized to one of three lifestyle-treatment programs with increasing level of intensity for 24 weeks. Body composition was measured by dual-energy X-ray absorptiometry (DXA), computed tomography, and multifrequency bioimpedance analysis both before and after therapy. Subjects demonstrated a "dose-response" effectiveness to three levels of lifestyle intervention to mitigate pioglitazone-induced weight gain. Mean (s.d.) weight change (kg) for the usual, standard, and intensive lifestyle groups were 4.9 +/- 4.9 (P = 0.005), 1.8 +/- 3.4 (P = 0.02), and -0.2 +/- 4.4 (NS) respectively. Total body fat increased 2.6 +/- 3.4 kg (P = 0.04) for the usual group and decreased for the intensive group -0.4 +/- 3.5 (NS). Change in abdominal subcutaneous and visceral adipose tissue (VAT) did not differ between groups, although ratio of visceral/subcutaneous fat decreased for the standard and intensive groups (NS). Both usual (P < 0.05) and standard care (NS) groups gained total body water. This is the first prospective, randomized study that demonstrates the beneficial effect of participation in a comprehensive lifestyle-weight-management program on lessening of weight gain associated with pioglitazone.

Evaluation of the glycometabolic effects of ranolazine in patients with and without diabetes mellitus in the MERLIN-TIMI 36 randomized controlled trial

BACKGROUND

Ranolazine is a novel antianginal shown in an exploratory analysis in patients with diabetes mellitus and chronic angina to be associated with a decline in hemoglobin A(1c) (HbA(1c)). We designed a prospective evaluation of the effect of ranolazine on hyperglycemia as part of a randomized, double-blind, placebo-controlled outcomes trial.

METHODS AND RESULTS

We compared HbA(1c) (percentage) and the time to onset of a > or =1% increase in HbA(1c) among 4918 patients with acute coronary syndrome randomized to ranolazine or placebo in the MERLIN-TIMI 36 trial. Ranolazine significantly reduced HbA(1c) at 4 months compared with placebo (5.9% versus 6.2%; change from baseline, -0.30 versus -0.04; P<0.001). In patients with diabetes mellitus treated with ranolazine, HbA(1c) declined from 7.5 to 6.9 (change from baseline, -0.64; P<0.001). Diabetic patients were more likely to achieve an HbA(1c) <7% at 4 months with ranolazine compared with placebo (59% versus 49%; P<0.001) and were less likely to have a > or =1% increase in HbA(1c) (14.2% versus 20.6% at 1 year; hazard ratio, 0.63; 95% confidence interval, 0.51 to 0.77; P<0.001). Moreover, ranolazine reduced recurrent ischemia in diabetic patients (hazard ratio, 0.75; 95% confidence interval, 0.61 to 0.93; P=0.008). Notably, in patients without diabetes mellitus at baseline, the incidence of new fasting glucose >110 mg/dL or HbA(1c) > or =6% was reduced by ranolazine (31.8% versus 41.2%; hazard ratio, 0.68; 95% confidence interval, 0.53 to 0.88; P=0.003). Reported hypoglycemia did not increase with ranolazine (P=NS).

CONCLUSIONS

Ranolazine significantly improved HbA(1c) and recurrent ischemia in patients with diabetes mellitus and reduced the incidence of increased HbA(1c) in those without evidence of previous hyperglycemia. The mechanism of this effect is under investigation.

The failing diabetic heart: focus on diastolic left ventricular dysfunction

Diabetes mellitus (DM) is highly prevalent and is an important risk factor for congestive heart failure (HF). Increased left ventricular (LV) diastolic stiffness is recognized as the earliest manifestation of DM-induced LV dysfunction, but its pathophysiology remains incompletely understood. Mechanisms whereby DM increases LV diastolic stiffness differ between HF with normal LV ejection fraction (EF) (HFNEF) and HF with reduced LVEF (HFREF). In diabetic HFREF, fibrosis and deposition of advanced glycation end products (AGEs) are the most important contributors to high LV diastolic stiffness, whereas in diabetic HFNEF, elevated resting tension of hypertrophied cardiomyocytes is the most important contributor to high LV diastolic stiffness. As HF mortality remains high in DM despite proven efficacy of current treatments, better understanding of the pathophysiology of high LV diastolic stiffness could be beneficial for novel therapeutic strategies.

Thiazolidinediones: effects on the development and progression of type 2 diabetes and associated vascular complications

In addition to reducing hyperglycaemia, the metabolic actions of TZDs (pioglitazone and rosiglitazone) in theory might improve the prognosis of patients with type 2 diabetes. However, it appears from recent data that pioglitazone and rosiglitazone have different cardiovascular risk profiles. The scope of this paper is to examine the benefits and risks of pioglitazone and rosiglitazone. Three large clinical studies (DREAM, and ADOPT with rosiglitazone; PROactive with pioglitazone) have recently been reported. A lower annual rate of decline of ss-cell function observed with rosiglitazone in the ADOPT study, compared with metformin and glyburide (glibenclamide), along with a reduced progression to insulin use seen with pioglitazone in the PROactive study, provides evidence that TZDs are effective in treating progressive hyperglycaemia. In PROactive, although the primary endpoint was not met, pioglitazone was associated with a reduction in a secondary composite endpoint of clinical cardiovascular events in high-risk patients with existing macrovascular disease who were already receiving other glycaemic and cardiovascular medications. Further evidence supporting an anti-atherogenic effect of pioglitazone was gained from the PERISCOPE study of carotid intima-media thickness. Recent controversy concerning a possible increased risk of myocardial infarction associated with rosiglitazone has fuelled uncertainty about the risk-benefit profile of this agent. In 2008, an update of an American Diabetes Association-European Association for the Study of Diabetes consensus statement on initiation and adjustment of therapy in patients with type 2 diabetes advised clinicians against using rosiglitazone. Skeletal fractures have recently emerged as a side effect of both TZDs. Available data suggest that cardiovascular benefits observed with pioglitazone might not be a class effect of TZDs.

The effect of rosiglitazone on integrated cardiovascular performance, cardiac structure, function and myocardial triglyceride: trial design and rationale

The thiazolidinedione (TZD) class of medications has been associated with increased risk for peripheral oedema, as well as incident and worsening heart failure (HF). The mechanism of these observed effects remains unclear. Here we present the rationale and study design for a randomised clinical trial designed to evaluate the cardiac effects of rosiglitazone on integrated cardiovascular performance, cardiac structure and function. The study is a randomised, single-centre, double-blind, placebo-controlled, parallel-group clinical trial to evaluate the effect of rosiglitazone on integrated cardiovascular performance in a cohort of patients with type 2 diabetes mellitus (T2DM) at increased risk for developing heart failure (HF). Participants will be randomised to receive rosiglitazone or matching placebo for six months. All subjects will undergo maximal treadmill cardiopulmonary exercise testing at baseline and after six months on study drug, with the primary trial end point of peak oxygen uptake indexed to fat-free mass (VO 2peak-FFM). Approximately two-thirds of the study cohort will undergo cardiac magnetic resonance imaging (MRI) and spectroscopy (MRS) at baseline and after six months of study therapy to assess cardiac structure, function and myocardial triglyceride content. While concerns for peripheral oedema and HF continue to confound clinical use of TZD medications, the direct cardiac effects of these drugs remain poorly understood and the clinical relevance of these clinical observations remains unclear. The present study will combine a series of state-of-the-art assessments to evaluate the cardiac effects of rosiglitazone treatment.

Assessment of arterial stiffness, a translational medicine biomarker system for evaluation of vascular risk

AIMS

Stiffening of the large arteries is a common feature of aging and is exacerbated by a number of disorders such as hypertension, diabetes, and renal disease. Arterial stiffening is recognized as an important and independent risk factor for cardiovascular events. This article will provide a comprehensive review of the recent advance on assessment of arterial stiffness as a translational medicine biomarker for cardiovascular risk.

DISCUSSIONS

The key topics related to the mechanisms of arterial stiffness, the methodologies commonly used to measure arterial stiffness, and the potential therapeutic strategies are discussed. A number of factors are associated with arterial stiffness and may even contribute to it, including endothelial dysfunction, altered vascular smooth muscle cell (SMC) function, vascular inflammation, and genetic determinants, which overlap in a large degree with atherosclerosis. Arterial stiffness is represented by biomarkers that can be measured noninvasively in large populations. The most commonly used methodologies include pulse wave velocity (PWV), relating change in vessel diameter (or area) to distending pressure, arterial pulse waveform analysis, and ambulatory arterial stiffness index (AASI). The advantages and limitations of these key methodologies for monitoring arterial stiffness are reviewed in this article. In addition, the potential utility of arterial stiffness as a translational medicine surrogate biomarker for evaluation of new potentially vascular protective drugs is evaluated.

CONCLUSIONS

Assessment of arterial stiffness is a sensitive and useful biomarker of cardiovascular risk because of its underlying pathophysiological mechanisms. PWV is an emerging biomarker useful for reflecting risk stratification of patients and for assessing pharmacodynamic effects and efficacy in clinical studies.

The metabolic syndrome

The "metabolic syndrome" (MetS) is a clustering of components that reflect overnutrition, sedentary lifestyles, and resultant excess adiposity. The MetS includes the clustering of abdominal obesity, insulin resistance, dyslipidemia, and elevated blood pressure and is associated with other comorbidities including the prothrombotic state, proinflammatory state, nonalcoholic fatty liver disease, and reproductive disorders. Because the MetS is a cluster of different conditions, and not a single disease, the development of multiple concurrent definitions has resulted. The prevalence of the MetS is increasing to epidemic proportions not only in the United States and the remainder of the urbanized world but also in developing nations. Most studies show that the MetS is associated with an approximate doubling of cardiovascular disease risk and a 5-fold increased risk for incident type 2 diabetes mellitus. Although it is unclear whether there is a unifying pathophysiological mechanism resulting in the MetS, abdominal adiposity and insulin resistance appear to be central to the MetS and its individual components. Lifestyle modification and weight loss should, therefore, be at the core of treating or preventing the MetS and its components. In addition, there is a general consensus that other cardiac risk factors should be aggressively managed in individuals with the MetS. Finally, in 2008 the MetS is an evolving concept that continues to be data driven and evidence based with revisions forthcoming.

Thiazolidinediones in type 2 diabetes: a cardiology perspective

OBJECTIVE

To examine the cardiovascular effects of thiazolidinediones (TZDs), discuss concerns regarding this drug class and its relation to heart failure (HF) and myocardial infarction (MI), and address the clinical implications of HF and MI.

DATA SOURCES

Literature was accessed through MEDLINE (1979-April 2008) using the search terms type 2 diabetes mellitus, thiazolidinediones, cardiovascular events, heart failure, myocardial infarction, and edema. Reviews, meta-analyses, clinical trials, observational studies (case-control, cohort), and descriptive studies (case reports, case series) were included.

STUDY SELECTION AND DATA EXTRACTION

All articles that were written in English and identified from the data sources were reviewed.

DATA SYNTHESIS

The American Diabetes Association recommends metformin as first-line therapy for type 2 diabetes, with the subsequent addition of a TZD, sulfonylurea, or insulin if the target is not met. Beyond glucose lowering, TZDs improve various factors associated with cardiovascular risk. Whether the effects translate into beneficial cardiovascular outcomes is controversial. In PROactive (Prospective Pioglitazone Clinical Trial in Macrovascular Events), pioglitazone did not produce a significant reduction in the primary endpoint that included a composite of coronary and vascular deaths, but the secondary composite endpoint of all-cause mortality, MI, or stroke was significantly reduced. Concerns related to HF have led to warnings in the labeling of TZDs. The drugs are contraindicated in patients with New York Heart Association Class III or IV HF. Rosiglitazone, but not pioglitazone, is associated with an increased risk of myocardial ischemic events, although the absolute magnitude is extremely small.

CONCLUSIONS

Although the glycemic efficacy of TZDs is comparable to that of metformin, adverse effects and higher costs make TZDs less appealing for initial therapy. Among the TZDs, pioglitazone should be considered based on cardiovascular safety data. In combination with metformin, pioglitazone may be particularly beneficial for patients with diabetes and metabolic syndrome. For patients on rosiglitazone who are achieving glycemic goals and tolerating the therapy without apparent complications, rosiglitazone may be continued.