New England Journal of Medicine JUNE 08, 2015

Effect of Sitagliptin on Cardiovascular Outcomes in Type 2 Diabetes

Jennifer B. Green, M. Angelyn Bethel, Paul W. Armstrong, John B. Buse, et al. for the TECOS Study Group

Bottom Line

The TECOS trial demonstrated that the addition of sitagliptin to usual care in patients with type 2 diabetes and established cardiovascular disease did not increase the risk of major adverse cardiovascular events compared to placebo.

Key Findings

1. The primary composite cardiovascular endpoint (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina) occurred in 11.4% of patients in the sitagliptin group compared to 11.6% in the placebo group (hazard ratio, 0.98; 95% CI, 0.89 to 1.08; P<0.001 for non-inferiority).

2. There was no significant difference between the sitagliptin and placebo groups in the rate of hospitalization for heart failure (3.1% vs. 3.1%; hazard ratio, 1.00; 95% CI, 0.83 to 1.20).

3. Rates of death from any cause were similar between groups (7.5% in the sitagliptin group vs. 7.8% in the placebo group; hazard ratio, 0.96; 95% CI, 0.85 to 1.09).

4. Glycemic equipoise was maintained, with a small initial difference in HbA1c levels that narrowed to approximately 0.1% over the course of the study, indicating cardiovascular safety was independent of glucose-lowering efficacy.

Study Design

Design

RCT

Double-Blind

Sample

14,671

Patients

Duration

3.0 yr

Median

Setting

Multicenter, 38 countries

Population Patients aged ≥50 years with type 2 diabetes, established atherosclerotic cardiovascular disease, and HbA1c between 6.5% and 8.0%.

Intervention Sitagliptin 100 mg daily (or 50 mg if eGFR was 30–50 mL/min/1.73 m2) added to existing usual care.

Comparator Placebo added to existing usual care.

Outcome Time to first confirmed event of a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina.

Study Limitations

• The study enrolled patients with relatively well-controlled diabetes (HbA1c 6.5% to 8.0%), limiting the generalizability of results to populations with poorly controlled hyperglycemia.

• The median follow-up of 3.0 years may be insufficient to capture very long-term cardiovascular benefits or rare adverse events.

• The trial was strictly designed to assess non-inferiority rather than superiority, limiting its ability to conclude cardiovascular benefit.

Clinical Significance

The TECOS trial provided crucial evidence that the DPP-4 inhibitor sitagliptin can be used for glycemic management in high-risk patients with established cardiovascular disease without increasing cardiovascular risk, fulfilling post-marketing regulatory safety requirements.

Historical Context

Following the 2008 FDA guidance mandating that new anti-hyperglycemic therapies demonstrate cardiovascular safety, several trials were conducted to assess the cardiovascular risk profile of DPP-4 inhibitors; TECOS followed the SAVOR-TIMI 53 and EXAMINE trials, providing reassurance regarding the cardiovascular safety of the sitagliptin class.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

The TECOS trial was designed to evaluate the cardiovascular safety of sitagliptin. Based on its mechanism of action as a dipeptidyl peptidase-4 (DPP-4) inhibitor, how does sitagliptin lower blood glucose, and why was a dedicated cardiovascular outcomes trial (CVOT) required for this medication class?

Key Response

Sitagliptin inhibits the DPP-4 enzyme, which normally degrades incretin hormones like GLP-1 and GIP. By prolonging the action of these hormones, it stimulates insulin secretion and suppresses glucagon in a glucose-dependent manner. Following the 2007 rosiglitazone controversy, which suggested increased cardiovascular risk, the FDA mandated that all new type 2 diabetes medications undergo CVOTs to demonstrate, at minimum, that they do not increase major adverse cardiovascular events (MACE).

Resident

In a patient with type 2 diabetes and established coronary artery disease, current guidelines often prioritize SGLT2 inhibitors or GLP-1 receptor agonists. Given the results of the TECOS trial, what is the clinical role of sitagliptin in this high-risk population, and how does its cardiovascular profile differ from the newer classes?

Key Response

TECOS demonstrated 'cardiovascular neutrality,' meaning sitagliptin did not increase or decrease MACE. Unlike SGLT2 inhibitors (e.g., empagliflozin) or certain GLP-1 receptor agonists (e.g., liraglutide), which have shown 'cardiovascular benefit' (superiority) in reducing MACE, sitagliptin is used when those agents are contraindicated, not tolerated, or when a weight-neutral, oral agent with low hypoglycemia risk is needed without the expectation of additional cardioprotection.

Fellow

The SAVOR-TIMI 53 trial using saxagliptin raised significant concerns regarding hospitalizations for heart failure (hHF). How did the TECOS results for sitagliptin impact the subspecialty understanding of DPP-4 inhibitors as a class regarding heart failure risk, and what are the implications for patients with baseline reduced ejection fraction?

Key Response

TECOS found no increase in hHF (HR 1.00; 95% CI 0.83-1.20), contrasting with the signal found in SAVOR-TIMI 53 (saxagliptin) and a non-significant trend in EXAMINE (alogliptin). This suggests that the risk of heart failure is not a class effect of DPP-4 inhibitors but rather molecule-specific or related to study populations. For fellows, this means sitagliptin (or linagliptin) is a preferred DPP-4 inhibitor option for patients with or at risk for heart failure if this class must be used.

Attending

A key feature of the TECOS trial was the 'treat-to-target' approach which resulted in only a 0.29% difference in HbA1c between the sitagliptin and placebo groups. How does this 'glycemic neutrality' strengthen the trial's findings regarding the direct cardiovascular effects of the drug molecule versus the effects of improved glucose control?

Key Response

By minimizing the difference in glycemic control between the two arms, TECOS largely isolated the pharmacological effects of sitagliptin from the metabolic benefits of lower blood sugar. This helps confirm that the observed cardiovascular safety was a direct property of the drug itself, rather than a byproduct of better HbA1c management, which is a common confounding factor in earlier diabetes trials (e.g., UKPDS).

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The TECOS trial utilized a non-inferiority design for its primary composite endpoint (MACE). Critically evaluate the choice of the non-inferiority margin (1.3 for the upper bound of the 95% CI) and discuss how the high rate of 'drop-in' medications in the placebo arm might impact the power and sensitivity of the trial to detect potential harm.

Key Response

The 1.3 margin is the standard FDA requirement for CVOTs. However, 'drop-in' therapy (placebo patients receiving other glucose-lowering drugs to maintain care) can dilute the treatment effect, biasing results toward the null. While this helps establish non-inferiority (safety), it makes it significantly harder to demonstrate superiority (benefit). Researchers must account for these 'compensation effects' when interpreting the lack of differentiation between treatment arms in long-term outcomes.

Journal Editor

As a reviewer, if you observed that the TECOS trial met its non-inferiority endpoint but showed no trend toward benefit despite high-risk enrollment, what specific concerns would you raise regarding the generalizability of these findings to a real-world primary prevention population?

Key Response

TECOS enrolled patients with 'established' cardiovascular disease (secondary prevention). A tough reviewer would note that while safety is established for the highest-risk patients, the benefit-risk ratio might differ in a lower-risk primary prevention population where the absolute risk of MACE is lower, potentially making even small, undetected safety signals or the lack of CV benefit more relevant in long-term therapy selection.

Guideline Committee

How did the TECOS trial specifically influence the ADA Standards of Care recommendations regarding the choice of DPP-4 inhibitors in patients with heart failure, and how does this compare to the level of evidence provided for SGLT2 inhibitors in the same guidelines?

Key Response

Following TECOS and the subsequent CARMELINA trial, guidelines (ADA Section 9) were updated to state that while SGLT2 inhibitors are the first-line choice for patients with heart failure (Level A evidence for benefit), if a DPP-4 inhibitor is required, sitagliptin or linagliptin are recommended over saxagliptin due to proven safety (Level A evidence for neutrality vs. Level B evidence for harm with saxagliptin).

Clinical Landscape

Noteworthy Related Trials

2013

SAVOR-TIMI 53 Trial

n = 16,492 · NEJM

Tested

Saxagliptin 5mg daily

Population

T2DM patients with history of or risk factors for CV disease

Comparator

Placebo

Endpoint

Composite of CV death, MI, or ischemic stroke

Key result: Saxagliptin did not increase or decrease the rate of ischemic events but resulted in an increased rate of hospitalization for heart failure.

2013

EXAMINE Trial

n = 5,380 · NEJM

Tested

Alogliptin 6.25/12.5/25mg daily

Population

T2DM patients with recent acute coronary syndrome

Comparator

Placebo

Endpoint

Composite of CV death, nonfatal MI, or nonfatal stroke

Key result: Alogliptin was noninferior to placebo with respect to major adverse cardiovascular events in patients with recent acute coronary syndrome.

2015

EMPA-REG OUTCOME Trial

n = 7,020 · NEJM

Tested

Empagliflozin 10/25mg daily

Population

T2DM patients with established CV disease

Comparator

Placebo

Endpoint

Composite of CV death, nonfatal MI, or nonfatal stroke

Key result: Empagliflozin significantly reduced the risk of CV death and hospitalization for heart failure compared to placebo.

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