Jardiance (empagliflozin) works by blocking a specific protein in your kidneys that normally recycles glucose back into your bloodstream. Instead of reabsorbing that glucose, your kidneys flush it out through urine. This single action triggers a cascade of benefits that extend well beyond blood sugar control, which is why Jardiance is now prescribed for heart failure and chronic kidney disease in addition to type 2 diabetes.
The Kidney Protein Jardiance Blocks
Your kidneys filter about 180 grams of glucose from your blood every day. Under normal circumstances, nearly all of it gets reabsorbed back into the bloodstream through transport proteins lining the tiny tubes (tubules) inside the kidney. The main transporter responsible for this recycling is called SGLT2, a high-capacity protein sitting on the surface of cells early in the kidney tubule. SGLT2 handles roughly 90% of all glucose reabsorption.
Jardiance selectively blocks SGLT2. With that transporter shut down, a significant portion of filtered glucose stays in the tubule and leaves the body in urine. The result is a meaningful drop in blood sugar that doesn’t depend on insulin. This is an important distinction: most diabetes medications work by increasing insulin production or improving insulin sensitivity. Jardiance sidesteps that system entirely, which is why it pairs well with other diabetes drugs and why it works even in people whose insulin-producing cells are struggling.
What That Means for Blood Sugar
The standard starting dose is 10 mg once daily, taken in the morning with or without food. If tolerated, your doctor may increase it to 25 mg. Because the drug causes your body to dump excess glucose through urine, it produces a steady, moderate reduction in blood sugar throughout the day rather than a sharp spike-and-drop pattern. The glucose-lowering effect naturally scales with how high your blood sugar is: the more glucose in your blood, the more gets filtered and excreted. When blood sugar is normal, less glucose is available to excrete, which lowers the risk of hypoglycemia compared to medications that stimulate insulin release.
How It Protects the Heart
Jardiance’s heart benefits were a surprise when they first emerged in clinical trials, and the mechanisms turn out to be more complex than just lowering blood sugar. The drug reduces the volume of fluid circulating in your body through two routes: it pulls extra glucose into the urine (which drags water along with it), and it increases sodium excretion. This mild diuretic effect reduces the amount of blood the heart has to pump with each beat and lowers the pressure the heart pumps against. For a heart that’s already weakened, this reduction in workload can be significant.
But the benefits go deeper than fluid management. At the cellular level, Jardiance appears to block a sodium-hydrogen exchange protein in heart muscle cells. When this exchanger is inhibited, sodium and calcium levels inside heart cells drop. Lower intracellular calcium helps the heart relax more fully between beats, which improves filling and overall pumping efficiency. There’s also evidence the drug reduces inflammation and scarring (fibrosis) in cardiac tissue, and that it shifts the heart’s fuel source toward ketone bodies, which are a more efficient energy source for a struggling heart muscle.
Clinical trials have confirmed these effects translate to real outcomes. In the EMPIRE-HF trial, patients on empagliflozin showed improvements in measures of heart pumping function, including how well the right side of the heart contracts. These findings are part of why Jardiance is now approved for heart failure regardless of whether the patient has diabetes.
How It Protects the Kidneys
The kidney protection mechanism is elegant. When Jardiance blocks glucose and sodium reabsorption early in the kidney tubule, more of those solutes flow downstream to a sensor point called the macula densa. This sensor detects the extra solute and triggers an automatic feedback loop that constricts the blood vessel feeding into the kidney’s filtering unit. The result is lower pressure inside the filter itself.
This matters because in diabetes and chronic kidney disease, the kidney filters often operate under abnormally high pressure, a state called hyperfiltration. Think of it like running a coffee filter under a fire hose instead of a gentle pour: over time, the excessive force damages the delicate filtering structures. By restoring more normal pressure, Jardiance slows the progressive kidney damage that characterizes these conditions. At the same time, the feedback loop dials down a hormonal system (the renin-angiotensin system) that further contributes to high pressure in the kidney filters.
Weight Loss and Blood Pressure Effects
Because you’re literally excreting calories in your urine, Jardiance produces modest weight loss. In clinical trials, patients lost an average of 1.7 to 1.9 kg (roughly 3.7 to 4.2 pounds) more than those on placebo. Most of this reduction comes from fat tissue rather than water weight alone. The fluid loss from increased urination also contributes to a reduction in blood pressure. These secondary effects are not dramatic on their own, but they complement the drug’s direct cardiovascular and metabolic benefits.
Common Side Effects
The most predictable side effects come directly from the mechanism. Extra glucose in your urine creates a favorable environment for yeast, so genital yeast infections are notably more common. In clinical trials, about 5.4% to 6.4% of women taking Jardiance developed genital yeast infections compared to 1.5% on placebo. For men, the rates were 1.6% to 3.1% versus 0.4% on placebo. These infections are generally mild and treatable, but they can be recurrent.
Urinary tract infections are also reported, though the increase over placebo is smaller. In pooled trial data, UTI rates were 9.3% for the 10 mg dose compared to 7.6% for placebo. When broken down by sex, UTI rates in women were 18.4% on the 10 mg dose versus 16.6% on placebo, while men showed rates of 3.6% versus 3.2%. Increased urination itself is expected and not a side effect per se; it’s the drug doing exactly what it’s designed to do.
Ketoacidosis Risk
A rarer but serious risk is a condition called euglycemic ketoacidosis, where the body develops dangerously high acid levels from ketone buildup even though blood sugar appears normal or only mildly elevated. This happens because Jardiance shifts the body’s metabolism in ways that can promote ketone production, and the blood sugar reading can be misleadingly reassuring (below 250 mg/dL) while the underlying chemistry is dangerous.
Certain factors raise this risk. People with low body weight or depleted energy stores are more vulnerable, as are those whose insulin-producing cells are already compromised. Common triggers include surgery, serious infections, prolonged fasting, dehydration, and persistent vomiting. Jardiance is not approved for type 1 diabetes in the United States specifically because ketoacidosis rates can reach as high as 9% in that population. Symptoms to be aware of include nausea, vomiting, abdominal pain, unusual fatigue, and difficulty breathing.