Rationale, design, and methods for glycemic control in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) Trial

Do Clinical Outcomes and Quality of Life Differ by the Number of Antianginals for Stable Ischemic Heart Disease? Insights from the BARI 2D Trial

Medical therapy, including antianginal treatment, is the cornerstone in the management of stable ischemic heart disease (SIHD). However, it remains unclear whether combining antianginal agents provides benefits beyond monotherapy in terms of quality of life (QoL) and cardiovascular outcomes. We used data from the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial, which compared cardiovascular and QoL outcomes in patients with SIHD and diabetes mellitus randomized to revascularization with intensive medical therapy or intensive medical therapy alone. We categorized patients into 3 groups: ≥2 versus 1 versus 0 antianginals. We compared patient characteristics, QoL metrics, and cardiovascular end points at baseline and at 5 years, creating a multivariable model to adjust for key clinical confounders. Of 2,368 patients, 348 patients (14.7%) were on 0 antianginals, 1,020 patients (43.1%) were on 1 antianginal, and 1,000 patients (42.2%) were on ≥2 antianginals at baseline. The most common antianginal class was β blockers. At baseline, patients on 0 antianginals had better QoL metrics (self-health score, Duke activity status index, and energy rating) than patients on ≥2 antianginals. However, at the 1-year follow-up, patients taking only 1 antianginal showed greater QoL improvement than those taking 0 antianginal, without any incremental benefit in QoL metrics seen in patients taking ≥2 antianginal agents, even after adjusting for multiple covariates such as age, heart failure, diabetes control, and myocardial jeopardy index. Lastly, at the 5-year follow-up, after adjustment, there were no differences in all-cause mortality, major adverse cardiovascular events, or myocardial infarction between patients taking different numbers of antianginals. Adults on a single antianginal for SIHD and diabetes mellitus had similar or better improvements in QoL than those on 2 or more antianginal agents at 1 year of follow-up. These findings merit further research to better understand the impact of medical therapy intensity on QoL in patients with SIHD and associated co-morbidities.

Aerobic exercise training may improve nerve function in type 2 diabetes and pre-diabetes: A systematic review

Diabetic neuropathy is a major complication of type 2 diabetes. Emerging evidence also suggests that people with pre-diabetes may develop similar symptoms related to nerve dysfunction. While regular exercise provides many benefits to patients with diabetes, whether exercise influences nerve function has not been established. As such, the aim of this systematic review was to evaluate current evidence regarding the effect of exercise training on the progression and development of diabetic neuropathy. A systematic search of MEDLINE (Ovid), CINAHL, AMED, PEDro, the Cochrane Library, Embase, and Scopus databases identified a total of 12 studies that were eligible for inclusion in this systematic review. Quality rating and data extraction were performed by two independent reviewers. The 12 included studies examined people with pre-diabetes (n = 1) and with type 2 diabetes (n = 11). There was heterogeneity of study quality and exercise type and dosage among these studies. Eleven studies reported that exercise training had a positive influence on nerve function or neuropathy-related symptoms; and only one study reported mild adverse events. Evidence from this systematic review suggests aerobic exercise training may positively influence nerve function among people with type 2 diabetes, with minimal risk of adverse events. Further research will be required to determine the optimal dosage of exercise training and the effect on nerve function in pre-diabetes and in women with previous gestational diabetes. This review is registered on PROSPERO (CRD42018088182).

Insulin and glucose-lowering agents for treating people with diabetes and chronic kidney disease

BACKGROUND

Diabetes is the commonest cause of chronic kidney disease (CKD). Both conditions commonly co-exist. Glucometabolic changes and concurrent dialysis in diabetes and CKD make glucose-lowering challenging, increasing the risk of hypoglycaemia. Glucose-lowering agents have been mainly studied in people with near-normal kidney function. It is important to characterise existing knowledge of glucose-lowering agents in CKD to guide treatment.

OBJECTIVES

To examine the efficacy and safety of insulin and other pharmacological interventions for lowering glucose levels in people with diabetes and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 February 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs looking at head-to-head comparisons of active regimens of glucose-lowering therapy or active regimen compared with placebo/standard care in people with diabetes and CKD (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2) were eligible.

DATA COLLECTION AND ANALYSIS

Four authors independently assessed study eligibility, risk of bias, and quality of data and performed data extraction. Continuous outcomes were expressed as post-treatment mean differences (MD). Adverse events were expressed as post-treatment absolute risk differences (RD). Dichotomous clinical outcomes were presented as risk ratios (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Forty-four studies (128 records, 13,036 participants) were included. Nine studies compared sodium glucose co-transporter-2 (SGLT2) inhibitors to placebo; 13 studies compared dipeptidyl peptidase-4 (DPP-4) inhibitors to placebo; 2 studies compared glucagon-like peptide-1 (GLP-1) agonists to placebo; 8 studies compared glitazones to no glitazone treatment; 1 study compared glinide to no glinide treatment; and 4 studies compared different types, doses or modes of administration of insulin. In addition, 2 studies compared sitagliptin to glipizide; and 1 study compared each of sitagliptin to insulin, glitazars to pioglitazone, vildagliptin to sitagliptin, linagliptin to voglibose, and albiglutide to sitagliptin. Most studies had a high risk of bias due to funding and attrition bias, and an unclear risk of detection bias.Compared to placebo, SGLT2 inhibitors probably reduce HbA1c (7 studies, 1092 participants: MD -0.29%, -0.38 to -0.19 (-3.2 mmol/mol, -4.2 to -2.2); I2 = 0%), fasting blood glucose (FBG) (5 studies, 855 participants: MD -0.48 mmol/L, -0.78 to -0.19; I2 = 0%), systolic blood pressure (BP) (7 studies, 1198 participants: MD -4.68 mmHg, -6.69 to -2.68; I2 = 40%), diastolic BP (6 studies, 1142 participants: MD -1.72 mmHg, -2.77 to -0.66; I2 = 0%), heart failure (3 studies, 2519 participants: RR 0.59, 0.41 to 0.87; I2 = 0%), and hyperkalaemia (4 studies, 2788 participants: RR 0.58, 0.42 to 0.81; I2 = 0%); but probably increase genital infections (7 studies, 3086 participants: RR 2.50, 1.52 to 4.11; I2 = 0%), and creatinine (4 studies, 848 participants: MD 3.82 μmol/L, 1.45 to 6.19; I2 = 16%) (all effects of moderate certainty evidence). SGLT2 inhibitors may reduce weight (5 studies, 1029 participants: MD -1.41 kg, -1.8 to -1.02; I2 = 28%) and albuminuria (MD -8.14 mg/mmol creatinine, -14.51 to -1.77; I2 = 11%; low certainty evidence). SGLT2 inhibitors may have little or no effect on the risk of cardiovascular death, hypoglycaemia, acute kidney injury (AKI), and urinary tract infection (low certainty evidence). It is uncertain whether SGLT2 inhibitors have any effect on death, end-stage kidney disease (ESKD), hypovolaemia, fractures, diabetic ketoacidosis, or discontinuation due to adverse effects (very low certainty evidence).Compared to placebo, DPP-4 inhibitors may reduce HbA1c (7 studies, 867 participants: MD -0.62%, -0.85 to -0.39 (-6.8 mmol/mol, -9.3 to -4.3); I2 = 59%) but may have little or no effect on FBG (low certainty evidence). DPP-4 inhibitors probably have little or no effect on cardiovascular death (2 studies, 5897 participants: RR 0.93, 0.77 to 1.11; I2 = 0%) and weight (2 studies, 210 participants: MD 0.16 kg, -0.58 to 0.90; I2 = 29%; moderate certainty evidence). Compared to placebo, DPP-4 inhibitors may have little or no effect on heart failure, upper respiratory tract infections, and liver impairment (low certainty evidence). Compared to placebo, it is uncertain whether DPP-4 inhibitors have any effect on eGFR, hypoglycaemia, pancreatitis, pancreatic cancer, or discontinuation due to adverse effects (very low certainty evidence).Compared to placebo, GLP-1 agonists probably reduce HbA1c (7 studies, 867 participants: MD -0.53%, -1.01 to -0.06 (-5.8 mmol/mol, -11.0 to -0.7); I2 = 41%; moderate certainty evidence) and may reduce weight (low certainty evidence). GLP-1 agonists may have little or no effect on eGFR, hypoglycaemia, or discontinuation due to adverse effects (low certainty evidence). It is uncertain whether GLP-1 agonists reduce FBG, increase gastrointestinal symptoms, or affect the risk of pancreatitis (very low certainty evidence).Compared to placebo, it is uncertain whether glitazones have any effect on HbA1c, FBG, death, weight, and risk of hypoglycaemia (very low certainty evidence).Compared to glipizide, sitagliptin probably reduces hypoglycaemia (2 studies, 551 participants: RR 0.40, 0.23 to 0.69; I2 = 0%; moderate certainty evidence). Compared to glipizide, sitagliptin may have had little or no effect on HbA1c, FBG, weight, and eGFR (low certainty evidence). Compared to glipizide, it is uncertain if sitagliptin has any effect on death or discontinuation due to adverse effects (very low certainty).For types, dosages or modes of administration of insulin and other head-to-head comparisons only individual studies were available so no conclusions could be made.

AUTHORS' CONCLUSIONS

Evidence concerning the efficacy and safety of glucose-lowering agents in diabetes and CKD is limited. SGLT2 inhibitors and GLP-1 agonists are probably efficacious for glucose-lowering and DPP-4 inhibitors may be efficacious for glucose-lowering. Additionally, SGLT2 inhibitors probably reduce BP, heart failure, and hyperkalaemia but increase genital infections, and slightly increase creatinine. The safety profile for GLP-1 agonists is uncertain. No further conclusions could be made for the other classes of glucose-lowering agents including insulin. More high quality studies are required to help guide therapeutic choice for glucose-lowering in diabetes and CKD.

Sex, Prescribing Practices and Guideline Recommended, Blood Pressure, and LDL Cholesterol Targets at Baseline in the BARI 2D Trial

Background. Research has shown less aggressive treatment and poorer control of cardiovascular disease (CVD) risk factors in women than men. Methods. We analyzed sex differences in pharmacotherapy strategies and attainment of goals for hemoglobin A1c (HbA1c), blood pressure (BP), and low density lipoprotein cholesterol (LDL-C) in patients with type 2 diabetes and established coronary artery disease enrolled into the BARI 2D trial. Results. Similar numbers of drugs were prescribed in both women and men. Women were less frequent on metformin or sulfonylurea and more likely to take insulin and to be on higher doses of hydroxymethylglutaryl-CoA reductase inhibitors (statins) than men. After adjusting for baseline differences and treatment prescribed, women were less likely to achieve goals for HbA1c (OR = 0.71, 95% CI 0.57, 0.88) and LDL-C (OR = 0.64, 95% CI 0.53, 0.78). More antihypertensives were prescribed to women, and yet BP ≤ 130/80 mmHg did not differ by sex. Conclusions. Women entering the BARI 2D trial were as aggressively treated with drugs as men. Despite equivalent treatment, women less frequently met targets for HbA1c and LDL-C. Our findings suggest that there may be sex differences in response to drug therapies used to treat diabetes, hypertension, and hyperlipidemia.

Determinants of successful glycemic control among participants in the BARI 2D trial: a post-hoc analysis

OBJECTIVE

The BARI 2D trial compared insulin provision (IP) versus insulin sensitization (IS) for the primary outcome of total mortality in participants with T2DM and cardiovascular disease (CVD). In this analysis we examine baseline characteristics that are associated with successful long-term glycemic control.

RESEARCH DESIGN AND METHODS

In a 2×2 factorial design, 2368 participants were randomized to either IP or IS therapy, and to either prompt revascularization with medical therapy or medical therapy alone. Successful long-term glycemic control (success) was defined by simultaneously meeting 1) a mean HbA1c level of <7.0% after each participant's third year of follow-up period, and 2) adherence with medications only from the assigned glycemic treatment arm during >80% of the BARI 2D follow-up. The association between baseline variables and success was determined using unadjusted and adjusted logistic regression models.

RESULTS

1917 participants (962 IP and 955 IS participants) had sufficiently long follow-up and data for this analysis. Among these IP and IS participants, 235 and 335 participants met both criteria of success, respectively (p<0.001). Those not on insulin at entry had higher odds of success (OR 2.25; CI 1.79-2.82) when treated with IS versus IP medications, irrespective of baseline HbA1c levels. Younger age, shorter duration of T2DM, and lower HbA1c at baseline were also each independently associated with higher success when treated with IS versus IP medications.

CONCLUSION

Patients similar to those in the BARI 2D trial may have a higher chance of achieving success with IS versus IP medications if they are younger, have shorter duration of T2DM, have lower HbA1c levels, have moderate or strenuous physically activity, and are not on insulin. In contrast, increasing age, longer duration of T2DM, higher HbA1c, and insulin therapy are associated with increased chance of success if treated with IP medications.

Favorable effects of insulin sensitizers pertinent to peripheral arterial disease in type 2 diabetes: results from the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial

OBJECTIVE

The aim of this manuscript was to report the risk of incident peripheral arterial disease (PAD) in a large randomized clinical trial that enrolled participants with stable coronary artery disease and type 2 diabetes and compare the risk between assigned treatment arms.

RESEARCH DESIGN AND METHODS

The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial randomly assigned participants to insulin sensitization (IS) therapy versus insulin-providing (IP) therapy for glycemic control. Results showed similar 5-year mortality in the two glycemic treatment arms. In secondary analyses reported here, we examine the effects of treatment assignment on the incidence of PAD. A total of 1,479 BARI 2D participants with normal ankle-brachial index (ABI) (0.91-1.30) were eligible for analysis. The following PAD-related outcomes are evaluated in this article: new low ABI≤0.9, a lower-extremity revascularization, lower-extremity amputation, and a composite of the three outcomes.

RESULTS

During an average 4.6 years of follow-up, 303 participants experienced one or more of the outcomes listed above. Incidence of the composite outcome was significantly lower among participants assigned to IS therapy than those assigned to IP therapy (16.9 vs. 24.1%; P<0.001). The difference was significant in time-to-event analysis (hazard ratio 0.66 [95% CI 0.51-0.83], P<0.001) and remained significant after adjustment for in-trial HbA1c (0.76 [0.59-0.96], P=0.02).

CONCLUSIONS

In participants with type 2 diabetes who are free from PAD, a glycemic control strategy of insulin sensitization may be the preferred therapeutic strategy to reduce the incidence of PAD and subsequent outcomes.

Tree-based identification of subgroups for time-varying covariate survival data

Classification and regression tree analyses identify subsets of a sample that differ on an outcome. Discrimination of subsets is performed using recursive binary splitting on a set of covariates, allowing for interactions of variable subgroups not easily captured in standard model building techniques. Using classification and regression tree with epidemiological data can be problematic as there is often a need to adjust for potential confounders and to account for time-varying covariates in the context of right-censored survival data. While classification and regression tree variations exist individually for survival analysis, time-varying covariates and incorporating possible confounders, examples of classification and regression tree using all three together are lacking. We propose a method to identify subsets of time-varying covariate risk factors that affect survival while adjusting for possible confounders. The technique is demonstrated on data from the Bypass Angioplasty Revascularization Investigation 2 Diabetes clinical trial to find combinations of modifiable time-varying cardiac risk factors (e.g. smoking status, blood pressure, lipid levels and HbA1c level) that are associated with time-to-event clinical outcomes.

Perioperative glycaemic control for diabetic patients undergoing surgery

BACKGROUND

Patients with diabetes mellitus are at increased risk of postoperative complications. Data from randomised clinical trials and meta-analyses point to a potential benefit of intensive glycaemic control, targeting near-normal blood glucose, in patients with hyperglycaemia (with and without diabetes mellitus) being submitted to surgical procedures. However, there is limited evidence concerning this question in patients with diabetes mellitus undergoing surgery.

OBJECTIVES

To assess the effects of perioperative glycaemic control for diabetic patients undergoing surgery.

SEARCH METHODS

Trials were obtained from searches of The Cochrane Library, MEDLINE, EMBASE, LILACS, CINAHL and ISIS (all up to February 2012).

SELECTION CRITERIA

We included randomised controlled clinical trials that prespecified different targets of perioperative glycaemic control (intensive versus conventional or standard care)

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. We summarised studies using meta-analysis or descriptive methods.

MAIN RESULTS

Twelve trials randomised 694 diabetic participants to intensive control and 709 diabetic participants to conventional glycaemic control. The duration of the intervention ranged from just the duration of the surgical procedure up to 90 days. The number of participants ranged from 13 to 421, and the mean age was 64 years. Comparison of intensive with conventional glycaemic control demonstrated the following results for our predefined primary outcomes: analysis restricted to studies with low or unclear detection or attrition bias for infectious complications showed a risk ratio (RR) of 0.46 (95% confidence interval (CI) 0.18 to 1.18), P = 0.11, 627 participants, eight trials, moderate quality of the evidence (grading of recommendations assessment, development and evaluation - (GRADE)). Evaluation of death from any cause revealed a RR of 1.19 (95% CI 0.89 to 1.59), P = 0.24, 1365 participants, 11 trials, high quality of the evidence (GRADE).On the basis of a posthoc analysis, there is the hypothesis that intensive glycaemic control may increase the risk of hypoglycaemic episodes if longer-term outcome measures are analysed (RR 6.92, 95% CI 2.04 to 23.41), P = 0.002, 724 patients, three trials, low quality of the evidence (GRADE). Analysis of our predefined secondary outcomes revealed the following findings: cardiovascular events had a RR of 1.03 (95% CI 0.21 to 5.13), P = 0.97, 682 participants, six trials, moderate quality of the evidence (GRADE) when comparing the two treatment modalities; and renal failure also did not show significant differences between intensive and regular glucose control (RR 0.61, 95% CI 0.34 to 1.08), P = 0.09, 434 participants, two trials, moderate quality of the evidence (GRADE). We did not meta-analyse length of hospital stay and intensive care unit (ICU) stay due to substantial unexplained heterogeneity. Mean differences between intensive and regular glucose control groups ranged from -1.7 days to 2.1 days for ICU stay and between -8 days to 3.7 days for hospital stay (moderate quality of the evidence (GRADE)). One trial assessed health-related quality of life in 12/37 (32.4%) of participants in the intervention group and 13/44 (29.5%) of participants in the control group, and did not show an important difference (low quality of the evidence (GRADE)) in the measured physical health composite score of the short-form 12-item health survey (SF-12). None of the trials examined the effects of the interventions in terms of costs.

AUTHORS' CONCLUSIONS

The included trials did not demonstrate significant differences for most of the outcomes when targeting intensive perioperative glycaemic control compared with conventional glycaemic control in patients with diabetes mellitus. However, posthoc analysis indicated that intensive glycaemic control was associated with an increased number of patients experiencing hypoglycaemic episodes. Intensive glycaemic control protocols with near-normal blood glucose targets for patients with diabetes mellitus undergoing surgical procedures are currently not supported by an adequate scientific basis. We suggest that insulin treatment regimens, patient- and health-system relevant outcomes, and time points for outcome measures should be defined in a thorough and uniform way in future studies.

Presentation in patients with angiographically documented coronary artery disease and type II diabetes mellitus (from the BARI 2D Clinical Trial)

Clinically stable patients with type 2 diabetes mellitus and coronary artery disease are not often thought to present with the symptom of typical angina. The aims of this study were to enumerate the proportion of patients presenting with typical angina or other cardiac symptoms and to elucidate what important clinical variables are associated with the presence of typical angina in patients with type 2 diabetes mellitus and angiographically documented coronary artery disease. Symptoms of angina, anginal equivalents, or an absence of symptoms were obtained using baseline data from the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial (n = 2,319). A bivariate analysis stratified by the presence or absence of previous revascularization and logistic regression modeling with a stepwise covariate selection was used. Eighty-two percent of patients had symptoms, while 18% presented asymptomatically. This was further divided approximately into typical angina (1/5), anginal equivalents (1/5), combination (2/5), and asymptomatic (1/5). A history of previous revascularization was a determinant of the type of symptom presentation with regard to the variables gender, age, current insulin use, myocardial jeopardy index score, and use of β blockers. In the multivariate logistic regression analysis, of the available candidate variables, only a history of β-blocker use (odds ratio 1.53, 95% confidence interval 1.24 to 1.94, p <0.0001) and previous percutaneous coronary intervention (odds ratio 1.55, 95% confidence interval 1.24 to 1.94, p <0.0001) had higher odds of an association with typical angina. In conclusion, a large proportion of patients with type 2 diabetes mellitus and coronary artery disease indeed have symptoms. Future studies of long-term outcomes associated with these symptoms are needed.

Cardiovascular risk and thiazolidinediones--what do meta-analyses really tell us?

Meta-analyses of clinical trials suggest that the use of the thiazolidinedione (TZD), rosiglitazone, in patients with type 2 diabetes mellitus may increase the risk of myocardial ischaemic events by 30-40%. Although these controversial data must be interpreted with caution, in the absence of definitive prospective cardiovascular (CV) outcomes data, they represent a prominent source of evidence concerning the CV safety of rosiglitazone. The results of meta-analyses and a large randomized-controlled CV outcomes trial provide strong evidence that pioglitazone does not increase the risk of coronary events. This article clarifies the clinical significance of these meta-analytical findings alongside other sources of evidence and assesses their impact on evolving treatment guidelines and recommendations for the use of TZDs in patients with type 2 diabetes.

Health status after treatment for coronary artery disease and type 2 diabetes mellitus in the Bypass Angioplasty Revascularization Investigation 2 Diabetes trial

BACKGROUND

Health status is a key outcome for comparing treatments, particularly when mortality does not differ significantly.

METHODS AND RESULTS

Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) randomized 2368 patients with type 2 diabetes mellitus and stable ischemic heart disease to (1) prompt revascularization versus medical therapy and (2) insulin sensitization versus insulin provision. Randomization was stratified by the intended method of revascularization, coronary artery bypass graft surgery or percutaneous coronary intervention. The Duke Activity Status Index and RAND Energy, Health Distress, and Self-Rated Health scales were assessed at study entry and annually thereafter; linear mixed models were used to evaluate the effect of randomized treatment on these measures. Health status improved significantly from baseline to 1 year (P<0.001) in each randomized treatment group. Compared with medical therapy, prompt revascularization was associated with significantly greater improvements in Duke Activity Status Index (1.32 points; P<0.001), Energy (1.36 points; P=0.02), and Self-rated Health (1.77 points; P=0.007) but not Health Distress (-0.47; P=0.46). These treatment effects were largely maintained over 4 years of follow-up. The effect of revascularization on the Duke Activity Status Index was significantly larger in the subgroup of patients intended for coronary artery bypass graft surgery compared with the subgroup intended for percutaneous coronary intervention. Health status did not differ significantly on any of the 4 measures between the insulin provision and insulin sensitization strategies.

CONCLUSIONS

Prompt coronary revascularization was associated with small yet statistically significant improvements in health status compared with initial medical therapy among patients with diabetes mellitus and stable ischemic heart disease.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT00006305.

Peroxisome proliferator-activated receptors, metabolic syndrome and cardiovascular disease

Metabolic syndrome (MetS) is a constellation of risk factors including insulin resistance, central obesity, dyslipidemia and hypertension that markedly increase the risk of Type 2 diabetes (T2DM) and cardiovascular disease (CVD). The peroxisome proliferators-activated receptor (PPAR) isotypes, PPARα, PPARδ/ß and PPARγ are ligand-activated nuclear transcription factors, which modulate the expression of an array of genes that play a central role in regulating glucose, lipid and cholesterol metabolism, where imbalance can lead to obesity, T2DM and CVD. They are also drug targets, and currently, PPARα (fibrates) and PPARγ (thiazolodinediones) agonists are in clinical use for treating dyslipidemia and T2DM, respectively. These metabolic characteristics of the PPARs, coupled with their involvement in metabolic diseases, mean extensive efforts are underway worldwide to develop new and efficacious PPAR-based therapies for the treatment of additional maladies associated with the MetS. This article presents an overview of the functional characteristics of three PPAR isotypes, discusses recent advances in our understanding of the diverse biological actions of PPARs, particularly in the vascular system, and summarizes the developmental status of new single, dual, pan (multiple) and partial PPAR agonists for the clinical management of key components of MetS, T2DM and CVD. It also summarizes the clinical outcomes from various clinical trials aimed at evaluating the atheroprotective actions of currently used fibrates and thiazolodinediones.

The Bypass Angioplasty Revascularization Investigation 2 Diabetes randomized trial of different treatment strategies in type 2 diabetes mellitus with stable ischemic heart disease: impact of treatment strategy on cardiac mortality and myocardial infarction

BACKGROUND

The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial in 2368 patients with stable ischemic heart disease assigned before randomization to percutaneous coronary intervention or coronary artery bypass grafting strata reported similar 5-year all-cause mortality rates with insulin sensitization versus insulin provision therapy and with a strategy of prompt initial coronary revascularization and intensive medical therapy or intensive medical therapy alone with revascularization reserved for clinical indication(s). In this report, we examine the predefined secondary end points of cardiac death and myocardial infarction (MI).

METHODS AND RESULTS

Outcome data were analyzed by intention to treat; the Kaplan-Meier method was used to assess 5-year event rates. Nominal P values are presented. During an average 5.3-year follow-up, there were 316 deaths (43% were attributed to cardiac causes) and 279 first MI events. Five-year cardiac mortality did not differ between revascularization plus intensive medical therapy (5.9%) and intensive medical therapy alone groups (5.7%; P=0.38) or between insulin sensitization (5.7%) and insulin provision therapy (6%; P=0.76). In the coronary artery bypass grafting stratum (n=763), MI events were significantly less frequent in revascularization plus intensive medical therapy versus intensive medical therapy alone groups (10.0% versus 17.6%; P=0.003), and the composite end points of all-cause death or MI (21.1% versus 29.2%; P=0.010) and cardiac death or MI (P=0.03) were also less frequent. Reduction in MI (P=0.001) and cardiac death/MI (P=0.002) was significant only in the insulin sensitization group.

CONCLUSIONS

In many patients with type 2 diabetes mellitus and stable ischemic coronary disease in whom angina symptoms are controlled, similar to those enrolled in the percutaneous coronary intervention stratum, intensive medical therapy alone should be the first-line strategy. In patients with more extensive coronary disease, similar to those enrolled in the coronary artery bypass grafting stratum, prompt coronary artery bypass grafting, in the absence of contraindications, intensive medical therapy, and an insulin sensitization strategy appears to be a preferred therapeutic strategy to reduce the incidence of MI.

Cardiovascular disease and intensive glucose control in type 2 diabetes mellitus: moving practice toward evidence-based strategies

Type 2 diabetes mellitus (T2DM) is associated with a high risk of complications, essentially macrovascular events. Surprisingly, the effect of improved glucose control on coronary and cerebrovascular complications and the target level of glycated hemoglobin (HbA(1c)) in this population remains questionable. We here report the results of 4 recently published randomized controlled trials (ACCORD, ADVANCE, VADT, UKPDS post-trial), which did not demonstrate a significant reduction of cardiovascular events in the intensive group compared to the standard group. On the contrary, in ACCORD, the study with the most ambitious goal (HbA(1c) < 6%), the overall and cardiovascular mortality was greater in the intensive group, although the risk of microangiopathic complications, especially nephropathy, was significantly decreased. VADT suggests that one possibility for the lack of observed effect of intensive therapy could be that the cardiovascular benefit is delayed. This contrasts strongly with the long-term postintervention outcomes of UKPDS, which show a persistent benefit of glycemic control during 10 years of post-trial follow-up ('legacy effect'). Therefore, the best way to protect patients with T2DM against coronary and cerebrovascular disease is to target all cardiovascular risk factors as early as possible by an individualized approach.

Cardiovascular disease and intensive glucose control in type 2 diabetes mellitus: moving practice toward evidence-based strategies

Type 2 diabetes mellitus (T2DM) is associated with a high risk of complications, essentially macrovascular events. Surprisingly, the effect of improved glucose control on coronary and cerebrovascular complications and the target level of glycated hemoglobin (HbA_1c) in this population remains questionable. We here report the results of 4 recently published randomized controlled trials (ACCORD, ADVANCE, VADT, UKPDS post-trial), which did not demonstrate a significant reduction of cardiovascular events in the intensive group compared to the standard group. On the contrary, in ACCORD, the study with the most ambitious goal (HbA_1c < 6%), the overall and cardiovascular mortality was greater in the intensive group, although the risk of microangiopathic complications, especially nephropathy, was significantly decreased. VADT suggests that one possibility for the lack of observed effect of intensive therapy could be that the cardiovascular benefit is delayed. This contrasts strongly with the long-term postintervention outcomes of UKPDS, which show a persistent benefit of glycemic control during 10 years of post-trial follow-up (‘legacy effect’). Therefore, the best way to protect patients with T2DM against coronary and cerebrovascular disease is to target all cardiovascular risk factors as early as possible by an individualized approach.

Impact of glycemic treatment choices on cardiovascular complications in type 2 diabetes

As the diabetic population has significant morbidity and mortality from cardiovascular disease (CVD), much of its medical care focuses on CVD prevention and treatment. Some medications used to treat hyperglycemia may have beneficial effects on CV outcomes, others may have negative effects, while still others seem to have no direct effect. Although past epidemiological studies have shown a relationship between glycated hemoglobin levels and CV events in patients with type 2 diabetes, recent large randomized clinical trials (ACCORD, ADVANCE, and VADT) lasting 3.5 to 5.6 years have found that intensive glycemic control either has no impact on CV outcomes or even worsens them. Results of the 10-year follow-up of the UKPDS suggest that tight glycemic control of younger, newly diagnosed patients with type 2 diabetes may have CV benefits many years later. Because the pathogenesis of atherosclerosis spans decades, it may be that beneficial effects of tight glycemic control on CV outcomes are mainly in younger patients without established macrovascular disease. There is an emerging notion that tight glycemic control may be beneficial in primary prevention of CVD in younger patients with diabetes, but may become deleterious in older patients with established or subclinical CVD. Thus, while tight control may lessen microvascular disease, it may increase the risk of hypoglycemia and possibly of adverse CV events. In each patient, the goals of glycemic control need to be individualized based on age, overall prognosis, presence of macrovascular disease, and risk of hypoglycemia.

Glycemic targets for patients with type 2 diabetes mellitus

Cardiovascular disease is the predominant cause of death in diabetic patients, and reducing the risk of cardiovascular disease in diabetics has recently been the focus of several highly publicized large trials, including ACCORD (Action To Control Cardiovascular Risk in Diabetes), ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation), and VADT (Veterans Affairs Diabetes Trial). These studies randomized high-risk diabetic patients into either intensive treatment or standard treatment. The glycemic control arm of ACCORD was terminated 17 months before the planned end of the study because of a finding of significantly increased all-cause and cardiovascular mortality in the intensive treatment group. These findings were not duplicated in either ADVANCE or VADT. Multiple possible explanations have been brought forward, including a higher incidence of death from unrecognized hypoglycemia, effects due to increased exposure to particular antidiabetic medications, adverse effects of rapid correction of hyperglycemia, weight gain, and differences in baseline characteristics. None of these were validated in post hoc analyses of the trial data, and the cause of the increased mortality remains elusive. Subgroup analyses suggest that those who start off with better control of their diabetes or without preexisting cardiovascular disease may have the most to gain from tight glycemic control. Reducing the risk of macrovascular disease and death in diabetic patients requires not only attention to glucose control but also meticulous attention to control of nonglycemic risk factors, including hypertension, hyperlipidemia, smoking, lack of exercise, and unhealthy diet as well as timely prescription of medications with proven preventative benefits, such as aspirin and statins.

A randomized trial of therapies for type 2 diabetes and coronary artery disease

BACKGROUND

Optimal treatment for patients with both type 2 diabetes mellitus and stable ischemic heart disease has not been established.

METHODS

We randomly assigned 2368 patients with both type 2 diabetes and heart disease to undergo either prompt revascularization with intensive medical therapy or intensive medical therapy alone and to undergo either insulin-sensitization or insulin-provision therapy. Primary end points were the rate of death and a composite of death, myocardial infarction, or stroke (major cardiovascular events). Randomization was stratified according to the choice of percutaneous coronary intervention (PCI) or coronary-artery bypass grafting (CABG) as the more appropriate intervention.

RESULTS

At 5 years, rates of survival did not differ significantly between the revascularization group (88.3%) and the medical-therapy group (87.8%, P=0.97) or between the insulin-sensitization group (88.2%) and the insulin-provision group (87.9%, P=0.89). The rates of freedom from major cardiovascular events also did not differ significantly among the groups: 77.2% in the revascularization group and 75.9% in the medical-treatment group (P=0.70) and 77.7% in the insulin-sensitization group and 75.4% in the insulin-provision group (P=0.13). In the PCI stratum, there was no significant difference in primary end points between the revascularization group and the medical-therapy group. In the CABG stratum, the rate of major cardiovascular events was significantly lower in the revascularization group (22.4%) than in the medical-therapy group (30.5%, P=0.01; P=0.002 for interaction between stratum and study group). Adverse events and serious adverse events were generally similar among the groups, although severe hypoglycemia was more frequent in the insulin-provision group (9.2%) than in the insulin-sensitization group (5.9%, P=0.003).

CONCLUSIONS

Overall, there was no significant difference in the rates of death and major cardiovascular events between patients undergoing prompt revascularization and those undergoing medical therapy or between strategies of insulin sensitization and insulin provision. (ClinicalTrials.gov number, NCT00006305.)

Is it possible to reduce cardiovascular risk with glucose-lowering approaches?

Diabetes mellitus is a strong, independent risk factor for cardiovascular events, and a key determinant of the level of this risk is the degree of glucose elevation. Clinical trials have not demonstrated that lowering glucose levels in people with established, long-duration diabetes mellitus has a clear cardiovascular benefit, and one trial reported that this approach increased mortality. In individuals with recent-onset diabetes mellitus, however, control of glucose level has established benefits on diabetes-related eye disease and kidney disease (which are themselves cardiovascular risk factors), and 10 years of intensive glucose control in these patients reduces the 15-20-year risk of myocardial infarction and mortality. These observations, along with the facts that the prevalence of diabetes mellitus is growing and that people typically have the disease for 20-40 years of their lives, support the importance of controlling glucose level and preventing its progressive rise over time. Currently available evidence suggests that therapeutic efforts that target hyperglycemia early in the course of diabetes have a long-term cardiovascular benefit.

Reassessing the cardiovascular risks and benefits of thiazolidinediones

This article is designed for the general cardiologist, endocrinologist, and internist caring for patients with diabetes and coronary artery disease. Despite the burden of coronary disease in diabetics, little is known about the impact of commonly used oral hypoglycemic agents on cardiovascular outcomes. As the untoward effects of insulin resistance (IR) are increasingly recognized, there is interest in targeting this defect. Insulin resistance contributes to dyslipidemia, hypertension, inflammation, hypercoagulability, and endothelial dysfunction. The aggregate impact of this process is progression of systemic atherosclerosis and an increased risk of adverse cardiovascular outcomes. As such, much attention has been paid to the peroxisome-proliferator-activated receptor gamma (PPARg) agonists rosiglitazone and pioglitazone (thiazolidinediones [TZDs]). Many studies have demonstrated a beneficial effect on the atherosclerotic process; specifically, these agents have been shown to reduce markers of inflammation, retard progression of carotid intimal thickness, prevent restenosis after coronary stenting, and prevent cardiovascular death and myocardial infarction in 1 large trial. Such benefits come at the risk of fluid retention and heart failure (HF) exacerbation, and the net effect on plasma lipids is still poorly understood. Thus, the aggregate risk-benefit ratio is poorly defined. A recent meta-analysis has raised significant concerns regarding the overall cardiovascular safety of 1 particular PPARg agonist (rosiglitazone), prompting international debate and regulatory changes. This review scrutinizes the clinical evidence regarding the cardiovascular risks and benefits of PPARg agonists. Future studies of PPARg agonists, and other emerging drugs that treat IR and diabetes, must be designed to look at cardiovascular outcomes.

Baseline characteristics of patients with diabetes and coronary artery disease enrolled in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial

BACKGROUND

The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial was undertaken to determine whether early revascularization intervention is superior to deferred intervention in the presence of aggressive medical therapy and whether antidiabetes regimens targeting insulin sensitivity are more or less effective than regimens targeting insulin provision in reducing cardiovascular events among patients with type 2 diabetes mellitus and stable coronary artery disease (CAD).

METHODS

The BARI 2D trial is a National Institutes of Health-sponsored randomized clinical trial with a 2 x 2 factorial design. Between 2001 and 2005, 49 clinical sites in North America, South America, and Europe randomized 2,368 patients. At baseline, the trial collected data on clinical history, symptoms, and medications along with centralized evaluations of angiograms, electrocardiograms, and blood and urine specimens.

RESULTS

Most of the BARI 2D patients were referred from the cardiac catheterization laboratory (54%) or cardiology clinic (27%). Of the randomized participants, 30% were women, 34% were minorities, 61% had angina, and 67% had multiregion CAD. Moreover, 29% had been treated with insulin, 58% had hemoglobin A(1c) >7.0%, 41% had low-density lipoprotein cholesterol >or=100 mg/dL, 52% had blood pressure >130/80 mm Hg, and 56% had body mass index >or=30 kg/m(2).

CONCLUSIONS

Baseline characteristics in BARI 2D are well balanced between the randomized treatment groups, and the clinical profile of the study cohort is representative of the target population. As a result, the BARI 2D clinical trial is in an excellent position to evaluate alternative treatment approaches for diabetes and CAD.

Effects of intensive glucose lowering in type 2 diabetes

BACKGROUND

Epidemiologic studies have shown a relationship between glycated hemoglobin levels and cardiovascular events in patients with type 2 diabetes. We investigated whether intensive therapy to target normal glycated hemoglobin levels would reduce cardiovascular events in patients with type 2 diabetes who had either established cardiovascular disease or additional cardiovascular risk factors.

METHODS

In this randomized study, 10,251 patients (mean age, 62.2 years) with a median glycated hemoglobin level of 8.1% were assigned to receive intensive therapy (targeting a glycated hemoglobin level below 6.0%) or standard therapy (targeting a level from 7.0 to 7.9%). Of these patients, 38% were women, and 35% had had a previous cardiovascular event. The primary outcome was a composite of nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes. The finding of higher mortality in the intensive-therapy group led to a discontinuation of intensive therapy after a mean of 3.5 years of follow-up.

RESULTS

At 1 year, stable median glycated hemoglobin levels of 6.4% and 7.5% were achieved in the intensive-therapy group and the standard-therapy group, respectively. During follow-up, the primary outcome occurred in 352 patients in the intensive-therapy group, as compared with 371 in the standard-therapy group (hazard ratio, 0.90; 95% confidence interval [CI], 0.78 to 1.04; P=0.16). At the same time, 257 patients in the intensive-therapy group died, as compared with 203 patients in the standard-therapy group (hazard ratio, 1.22; 95% CI, 1.01 to 1.46; P=0.04). Hypoglycemia requiring assistance and weight gain of more than 10 kg were more frequent in the intensive-therapy group (P<0.001).

CONCLUSIONS

As compared with standard therapy, the use of intensive therapy to target normal glycated hemoglobin levels for 3.5 years increased mortality and did not significantly reduce major cardiovascular events. These findings identify a previously unrecognized harm of intensive glucose lowering in high-risk patients with type 2 diabetes. (ClinicalTrials.gov number, NCT00000620.)

Relationship of glycemic control, exogenous insulin, and C-peptide levels to ischemic heart disease mortality over a 16-year period in people with older-onset diabetes: the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR)

OBJECTIVE

The purpose of this study was to examine the relationship of glycemic control and exogenous and endogenous insulin levels with all-cause and cause-specific mortality (ischemic heart disease and stroke) in an older-onset diabetic population.

RESEARCH DESIGN AND METHODS

The Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) is an ongoing, prospective, population-based cohort study of individuals with diabetes first examined in 1980-1982. A stratified sample of all individuals with diabetes diagnosed at 30 years of age or older was labeled "older-onset" (n = 1,370). Those participating in the 1984-1986 examination phase (n = 1,007) were included in the analysis. Endogenous insulin was determined by measurements of plasma C-peptide (in nanomoles per liter), and exogenous insulin was calculated in units per kilogram per day. Glycemic control was determined by levels of glycosylated hemoglobin (HbA(1)).

RESULTS

After 16 years of follow-up, 824 individuals died (all-cause mortality); 358 deaths involved ischemic heart disease and 137 involved stroke. C-peptide and HbA(1) were significantly associated with all-cause and ischemic heart disease mortality in our study. The hazard ratio (95% CI) values for all-cause mortality were 1.12 (1.07-1.17) per 1% increase in HbA(1), 1.20 (0.85-1.69) per 1 unit x kg(-1) x day(-1) increase in exogenous insulin, and 1.15 (1.04-1.29) per 1 nmol/l increase in C-peptide and for ischemic heart disease mortality were 1.14 (1.06-1.22), 1.50 (0.92-2.46), and 1.19 (1.02-1.39) for HbA(1), exogenous insulin, and C-peptide, respectively, after adjusting for relevant confounders. C-peptide was associated with stroke mortality only among men (1.65 [1.07-2.53]).

CONCLUSIONS

Our results show that individuals with higher endogenous insulin levels are at higher risk of all-cause, ischemic heart disease, and stroke mortality.

Should We Use PPAR Agonists to Reduce Cardiovascular Risk?

Trials of peroxisome proliferator-activated receptor (PPAR) agonists have shown mixed results for cardiovascular prevention. Fibrates are PPAR-alpha agonists that act primarily to improve dyslipidemia. Based on low- and high-density lipoprotein cholesterol (LDL and HDL) effects, gemfibrozil may be of greater cardiovascular benefit than expected, fenofibrate performed about as expected, and bezafibrate performed worse than expected. Increases in both cardiovascular and noncardiovascular serious adverse events have been observed with some fibrates. Thiazolidinediones (TZDs) are PPAR-gamma agonists used to improve impaired glucose metabolism but also influence lipids. Pioglitazone reduces atherosclerotic events in diabetic subjects, but has no net cardiovascular benefit due to increased congestive heart failure risk. Rosiglitazone may increase the risk of atherosclerotic events, and has a net harmful effect on the cardiovascular system when congestive heart failure is included. The primary benefit of TZDs appears to be the prevention of diabetic microvascular complications. Dual PPAR-alpha/gamma agonists have had unacceptable adverse effects but more selective agents are in development. PPAR-delta and pan-agonists are also in development. It will be imperative to prove that future PPAR agonists not only prevent atherosclerotic events but also result in a net reduction on total cardiovascular events without significant noncardiovascular adverse effects with long-term use.

Association of plasma resistin with glomerular filtration rate and albuminuria in hypertensive adults

Resistin, a recently discovered proinflammatory cytokine, has been variably associated with insulin resistance, inflammation, and renal dysfunction. We investigated the association of plasma resistin with estimated glomerular filtration rate and albuminuria in 1575 hypertensive adults without known coronary heart disease or stroke (857 blacks and 718 non-Hispanic whites). Resistin was measured by a solid phase sandwich immunoassay, estimated glomerular filtration rate was estimated from serum creatinine, and albuminuria was expressed as urine albumin:creatinine ratio. After adjustment for coronary heart disease risk factors (age, sex, body mass index, smoking history, systolic blood pressure, diabetes, and total and high-density lipoprotein cholesterol) and use of renin-angiotensin blockers and statins, higher plasma resistin levels were associated with lower estimated glomerular filtration rate in both ethnic groups (each P<0.0001); the association remained significant after further adjustment for a marker of insulin resistance (homeostasis model assessment for insulin resistance) and a marker of inflammation (plasma C-reactive protein) and was seen in subjects with and without diabetes (each P<0.0001) in both ethnic groups. Higher plasma resistin levels were associated with a higher urine albumin:creatinine ratio in black subjects with diabetes (P<0.0001) and non-Hispanic white subjects with diabetes (P=0.032), independent of coronary heart disease risk factors, hypertension medication use, and statin use; the association remained significant after additional adjustment for homeostasis model assessment for insulin resistance and C-reactive protein. In adults with hypertension, higher circulating resistin levels were associated with a lower estimated glomerular filtration rate and with increased urine albumin:creatinine ratio in the presence of concomitant diabetes. This association was independent of coronary heart disease risk factors and markers of insulin resistance and inflammation.