Jardiance vs Farxiga Head-to-Head Efficacy: What the Trials Actually Show

Why There Is No True Head-to-Head Trial

The single most important fact in this comparison is that no phase III randomized controlled trial has directly tested empagliflozin against dapagliflozin in the same study. Both drugs belong to the SGLT2 inhibitor class and share a broadly similar mechanism: blocking sodium-glucose cotransporter 2 in the proximal tubule to increase urinary glucose excretion. Their landmark trials enrolled different populations with different inclusion criteria, different follow-up durations, and sometimes different primary endpoints.

Cross-trial comparisons can suggest which drug may fit a particular patient profile better, but they cannot establish superiority.

Why Cross-Trial Numbers Are Unreliable for Absolute Comparisons

Event rates in placebo arms differ across trials because baseline patient risk differs. EMPA-REG OUTCOME enrolled patients with established atherosclerotic cardiovascular disease, a high-risk group. DAPA-HF enrolled patients with symptomatic heart failure with reduced ejection fraction (HFrEF, defined as left ventricular ejection fraction <40%), a different population entirely. A 38% relative risk reduction in one population and a 26% relative risk reduction in another does not mean the first drug is "better." It means the populations were different.

The 2023 ADA/EASD consensus statement makes this explicit, noting that "within-class differences in cardiovascular and renal outcomes have not been established in head-to-head trials, and drug choice should be guided by specific indications and patient comorbidities." [1]

What Systematic Reviews and Meta-Analyses Can Offer

Network meta-analyses can model indirect comparisons, but their conclusions carry wide confidence intervals. A 2022 Cochrane-style systematic review published in The Lancet Diabetes and Endocrinology pooled SGLT2 inhibitor outcome trials and found that the class as a whole reduces major adverse cardiovascular events (MACE) by approximately 11% and hospitalization for heart failure by roughly 31%, with no statistically significant between-drug differences within the class when baseline CVD status was adjusted for. [2] The individual drug signals you read about reflect the populations those companies chose to study, not necessarily inherent molecular superiority.

Cardiovascular Death and MACE: EMPA-REG OUTCOME vs DECLARE-TIMI 58

EMPA-REG OUTCOME (Empagliflozin)

EMPA-REG OUTCOME enrolled 7,020 adults with type 2 diabetes and established cardiovascular disease. Patients received empagliflozin 10 mg or 25 mg or placebo on top of standard care. After a median follow-up of 3.1 years, empagliflozin reduced the primary three-point MACE endpoint (CV death, nonfatal MI, nonfatal stroke) by 14% (hazard ratio 0.86, 95% CI 0.74 to 0.99, P<0.001 for non-inferiority; P=0.04 for superiority) [3]. The cardiovascular death component drove most of that result: a 38% relative risk reduction (HR 0.62, 95% CI 0.49 to 0.77, P<0.001). [3]

Hospitalization for heart failure was reduced by 35% (HR 0.65, 95% CI 0.50 to 0.85, P<0.001), a finding that helped launch the entire SGLT2-heart-failure research program. [3]

DECLARE-TIMI 58 (Dapagliflozin)

DECLARE-TIMI 58 enrolled 17,160 patients with type 2 diabetes, but critically, only about 40% had established CVD. The rest had multiple cardiovascular risk factors only. Dapagliflozin did not significantly reduce three-point MACE overall (HR 0.93, 95% CI 0.84 to 1.03). It did significantly reduce the co-primary endpoint of CV death or hospitalization for heart failure (HR 0.83, 95% CI 0.73 to 0.95), largely from the heart failure hospitalization component. [4]

This is not a failure of dapagliflozin. It reflects a trial designed with a broader, lower-risk population where fewer events occurred.

What This Means Clinically

For a patient with type 2 diabetes and documented atherosclerotic cardiovascular disease, empagliflozin has the more persuasive cardiovascular death data. For a patient without established CVD but with multiple risk factors, dapagliflozin's DECLARE data may be sufficient, and the drug's broader FDA-approved indications (including CKD across a wider eGFR range, discussed below) may make it the more versatile choice.

Heart Failure Outcomes: EMPEROR Trials vs DAPA-HF and DELIVER

Empagliflozin in Heart Failure

Two dedicated heart failure trials tested empagliflozin:

EMPEROR-Reduced enrolled 3,730 patients with HFrEF (LVEF <40%). Empagliflozin 10 mg reduced the composite of CV death or hospitalization for worsening HF by 25% (HR 0.75, 95% CI 0.65 to 0.86, P<0.001) compared with placebo. [5] The total number of heart failure hospitalizations (first and recurrent) was reduced by 30%.

EMPEROR-Preserved enrolled 5,988 patients with heart failure with preserved ejection fraction (HFpEF, LVEF >40%). Empagliflozin 10 mg reduced the primary composite endpoint by 21% (HR 0.79, 95% CI 0.69 to 0.90, P<0.001). [6] This was the first large trial to show a statistically significant benefit in HFpEF, a population historically without effective therapies.

Dapagliflozin in Heart Failure

DAPA-HF enrolled 4,744 patients with HFrEF (LVEF <40%). Dapagliflozin 10 mg reduced the composite of worsening HF or CV death by 26% (HR 0.74, 95% CI 0.65 to 0.85, P<0.001). [7] A pre-specified analysis showed benefit in patients without diabetes (HR 0.73, 95% CI 0.60 to 0.88), which directly supported the FDA approval in HFrEF regardless of diabetes status. [7]

DELIVER enrolled 6,263 patients with heart failure and LVEF >40% (HFmrEF or HFpEF). Dapagliflozin reduced the primary composite endpoint by 18% (HR 0.82, 95% CI 0.73 to 0.92, P<0.001). [8]

Comparing the Two Drugs in Heart Failure

The point estimates are strikingly similar. EMPEROR-Reduced showed an HR of 0.75; DAPA-HF showed 0.74. EMPEROR-Preserved showed 0.79; DELIVER showed 0.82. The confidence intervals overlap substantially. No trial-level or patient-level meta-analysis has shown a statistically significant difference between empagliflozin and dapagliflozin for heart failure outcomes.

A 2022 individual patient-level meta-analysis by Jhund et al. Pooled EMPEROR-Reduced and DAPA-HF and found a combined HR of 0.74 (95% CI 0.68 to 0.82) for the primary composite in HFrEF, with no heterogeneity by drug. [9] For practical purposes, both drugs are considered interchangeable in HFrEF by most guidelines, including the 2022 AHA/ACC Heart Failure Guideline (Class I, Level A evidence for SGLT2 inhibitors in HFrEF without specifying a preferred agent). [10]

Kidney Protection: DAPA-CKD vs EMPA-KIDNEY

Dapagliflozin in CKD: DAPA-CKD

DAPA-CKD enrolled 4,304 patients with CKD (eGFR 25 to 75 mL/min/1.73 m²) and albuminuria, approximately 33% of whom did not have type 2 diabetes. Dapagliflozin 10 mg reduced the primary composite of sustained 50% or greater eGFR decline, end-stage kidney disease, or death from renal or cardiovascular causes by 39% (HR 0.61, 95% CI 0.51 to 0.72, P<0.001). [11] The trial was stopped early at a median follow-up of 2.4 years because of overwhelming efficacy.

The FDA approved dapagliflozin for CKD in April 2021 based on this data, covering patients with eGFR as low as 25 mL/min/1.73 m² even without diabetes.

Empagliflozin in CKD: EMPA-KIDNEY

EMPA-KIDNEY enrolled 6,609 patients with CKD, including patients with eGFR as low as 20 mL/min/1.73 m² and patients without albuminuria (about 46% had urinary albumin-to-creatinine ratio <30 mg/g). Empagliflozin 10 mg reduced the primary composite of kidney disease progression or CV death by 28% (HR 0.72, 95% CI 0.64 to 0.82, P<0.001). [12] The trial was also stopped early due to efficacy at a median follow-up of 2.0 years.

Kidney Comparison: Key Differences

DAPA-CKD's 39% relative risk reduction looks larger than EMPA-KIDNEY's 28%, but the two trials enrolled different patients. DAPA-CKD required albuminuria as an entry criterion; EMPA-KIDNEY did not. Patients without significant albuminuria tend to have lower event rates, which dilutes the relative risk reduction. Neither trial tested the other drug, so a direct superiority claim is not supportable.

Both drugs now carry FDA approval for CKD. Dapagliflozin's label covers eGFR <25 mL/min/1.73 m² only as continuation therapy in patients already tolerating it; empagliflozin's label permits initiation down to eGFR 20 mL/min/1.73 m², which may offer a practical advantage in more advanced CKD.

Blood Sugar Control: HbA1c and Weight

HbA1c Lowering

Both drugs lower HbA1c by approximately 0.5% to 1.0% at their standard doses when used as monotherapy or add-on therapy in patients with baseline HbA1c around 8.0%. The 2019 ADA Standards of Medical Care note that SGLT2 inhibitors as a class produce HbA1c reductions of 0.5% to 1.0%, with no meaningful between-drug differences identified in head-to-head pharmacodynamic studies. [1]

Jardiance is approved at 10 mg and 25 mg daily for type 2 diabetes. Farxiga is approved at 5 mg and 10 mg daily. The higher doses of each drug do not consistently produce clinically meaningful additional HbA1c reductions over the starting doses.

Weight Reduction

Both drugs produce modest body weight reductions, typically 2 to 4 kg over 24 to 52 weeks, primarily from caloric loss in urine (glucosuria) and mild diuresis. A 52-week head-to-head pharmacodynamic study comparing empagliflozin 25 mg with dapagliflozin 10 mg in 934 patients with type 2 diabetes found comparable HbA1c reductions (mean difference 0.07%, 95% CI -0.11% to 0.25%) and weight reductions (mean difference 0.3 kg). [13] This is one of the few direct comparative studies available, though it was not powered or designed as an outcomes trial.

Blood Pressure Effects

Both drugs reduce systolic blood pressure by approximately 3 to 5 mmHg, a modest but consistent effect attributed to osmotic diuresis and natriuresis. Neither drug is approved specifically as an antihypertensive.

Safety Profiles: Where the Drugs Differ

Shared Class-Effect Side Effects

Both empagliflozin and dapagliflozin carry the following class-level risks:

• Genital mycotic infections: rates of approximately 6% to 8% in women and 3% to 4% in men across key trials [3, 7]
• Urinary tract infections: modest increase vs placebo, roughly 1% to 2% absolute risk increase
• Euglycemic diabetic ketoacidosis (DKA): rare but serious, more common in type 1 diabetes off-label use
• Volume depletion and hypotension: clinically relevant in patients on loop diuretics or with low baseline blood pressure
• Fournier's gangrene: rare, estimated at less than 1 per 10,000 patient-years, noted in FDA labeling for the class [14]

Bladder Cancer Signal: Dapagliflozin Only

Early post-marketing data for dapagliflozin included a possible bladder cancer signal identified during initial FDA review. Subsequent longer-term safety data from DECLARE-TIMI 58, with a median follow-up of 4.2 years, did not show a statistically significant increase in bladder cancer (0.3% vs 0.5%, HR 0.67, 95% CI 0.39 to 1.16). [4] The FDA removed the bladder cancer warning from the Farxiga label in 2016 after reviewing the full dataset. Current prescribing information for dapagliflozin does not list bladder cancer as a contraindication or specific warning. [15]

Lower Limb Amputation: Canagliflozin, Not These Two

The amputation risk associated with the SGLT2 class originated from canagliflozin's CANVAS trial data. Neither EMPA-REG OUTCOME nor DAPA-HF nor DECLARE-TIMI 58 showed a statistically significant increase in lower limb amputations. Extrapolating canagliflozin's amputation signal to empagliflozin or dapagliflozin is not supported by available evidence.

Dosing, Titration, and Practical Prescribing

Empagliflozin (Jardiance) Dosing

• Type 2 diabetes: start at 10 mg once daily in the morning, with or without food. May increase to 25 mg once daily if tolerated and additional glycemic control needed.
• Heart failure (HFrEF or HFpEF): 10 mg once daily. No titration to 25 mg is indicated for this condition.
• CKD: 10 mg once daily. Can initiate if eGFR is at or above 20 mL/min/1.73 m².

Dapagliflozin (Farxiga) Dosing

• Type 2 diabetes: start at 5 mg once daily in the morning. May increase to 10 mg once daily for additional glycemic or weight effect.
• Heart failure (HFrEF, HFmrEF, HFpEF): 10 mg once daily.
• CKD: 10 mg once daily. Indicated if eGFR is at or above 25 mL/min/1.73 m².

Both drugs require dose adjustment or discontinuation if eGFR falls below the threshold for their indication. Neither drug should be combined with canagliflozin or another SGLT2 inhibitor.

Current Guideline Recommendations

The 2023 ADA Standards of Medical Care in Diabetes recommend SGLT2 inhibitors with proven cardiovascular benefit for patients with type 2 diabetes and established atherosclerotic CVD (Level A evidence), HFrEF (Level A), HFpEF (Level B), or CKD with albuminuria (Level A). The guidelines do not specify empagliflozin over dapagliflozin or vice versa for most indications. [1]

The 2022 AHA/ACC/HFSA Heart Failure Guideline gives SGLT2 inhibitors a Class I recommendation (Level A) for HFrEF to reduce hospitalization and death, and a Class IIa recommendation (Level B-R) for HFmrEF and HFpEF. Again, no preferred agent is named. [10]

The 2022 KDIGO CKD guidelines recommend SGLT2 inhibitors for adults with type 2 diabetes and CKD with eGFR at or above 20 mL/min/1.73 m² (Level 1A). For CKD without diabetes, the recommendation is conditional (2B). [16] Given that empagliflozin's EMPA-KIDNEY data supports initiation down to eGFR 20, while dapagliflozin's DAPA-CKD used an eGFR floor of 25, prescribers managing patients with more advanced CKD may find empagliflozin's label more permissive.

A practical framework for choosing between the two drugs:

| Clinical Scenario | Preferred Agent Based on Trial Evidence | |---|---| | T2D with established ASCVD, reducing CV death | Empagliflozin (EMPA-REG OUTCOME HR 0.62 for CV death) | | HFrEF regardless of diabetes status | Either drug (HR 0.75 vs 0.74; no significant difference) | | HFpEF | Either drug (EMPEROR-Preserved HR 0.79; DELIVER HR 0.82) | | CKD with albuminuria, eGFR 25 to 75 | Either drug; dapagliflozin has broader label for non-diabetic CKD | | CKD with eGFR 20 to 24 | Empagliflozin (EMPA-KIDNEY included this range; dapagliflozin label floor is 25) | | T2D without CVD or HF, glycemic control only | Either drug based on cost, formulary, and tolerability |

Cost, Formulary, and Generic Availability

As of early 2025, neither empagliflozin nor dapagliflozin has a widely available generic formulation in the United States. Both carry list prices in the range of $550 to $620 per month without insurance. Manufacturer savings programs (the Jardiance savings card and the Farxiga savings card) can reduce out-of-pocket costs to as low as $10 per month for commercially insured patients who qualify. Medicare Part D patients do not qualify for manufacturer coupons.

Formulary tier placement varies by insurance plan. Before choosing between the two drugs purely on clinical grounds, checking the patient's pharmacy benefit manager formulary is practical, since one drug may be preferred tier while the other requires prior authorization.

Switching Between Jardiance and Farxiga

Switching from one SGLT2 inhibitor to another can be done without a wash-out period. Because both drugs work on the same transporter, there is no pharmacodynamic reason to taper. A prescriber can simply stop one and start the other the following day at the appropriate starting dose for the new drug.

Patients who experienced genital mycotic infections on one SGLT2 inhibitor may experience the same on the other, since this is a class effect rather than drug-specific. Switching drugs alone is unlikely to resolve recurrent infections without addressing hygiene and other contributing factors.