Jardiance (empagliflozin) typically lowers A1C by 0.7 to 0.9 percentage points when used on its own. So if your A1C is 8.0%, you can expect it to drop to roughly 7.1 to 7.3% over several months. That’s a meaningful reduction, though it’s moderate compared to some other diabetes medications.
The 10 mg vs. 25 mg Difference
Jardiance comes in two doses: 10 mg and 25 mg, taken once daily. Most people start at 10 mg. If that doesn’t bring your A1C to target, your doctor may increase to 25 mg, but the added benefit is small. The American Academy of Family Physicians notes that the higher dose produces “only minor A1C changes” beyond what the 10 mg dose achieves. In practical terms, you’re looking at roughly a 0.1 to 0.2 percentage point difference between the two doses.
This matters because some people assume doubling down on the dose will dramatically improve their numbers. It generally won’t. If 10 mg isn’t getting you where you need to be, adding or switching to a different class of medication is often more effective than bumping up to 25 mg alone.
How Long It Takes to Work
Jardiance starts working immediately. The drug causes your kidneys to flush excess glucose into your urine, and that process begins with the first dose. On 10 mg, your body eliminates about 64 grams of glucose per day through urine; on 25 mg, about 78 grams per day.
However, A1C reflects your average blood sugar over roughly three months, so the number on your lab work won’t shift overnight. Clinical trials measured significant A1C reductions at 24 weeks (about six months). The effect holds up over time: at two years, patients on 25 mg maintained an A1C reduction of 0.75 percentage points from their starting level. That durability is notable because some other diabetes medications lose effectiveness over the years.
Why Your Starting A1C Matters
People with higher baseline A1C levels tend to see larger absolute drops. If your A1C is 9% or above, Jardiance may pull it down more than the average 0.7 to 0.9 points. If you’re starting closer to 7.5%, the reduction will likely be on the smaller end. This is a common pattern across diabetes drugs, not something unique to Jardiance. The mechanism explains why: if your blood sugar is higher, more glucose gets filtered through the kidneys, and more gets flushed out by the drug.
There’s also a built-in safety floor. Jardiance stops lowering blood sugar once levels drop enough that your kidneys can reabsorb all the filtered glucose through a backup transport system. This means the risk of dangerously low blood sugar (hypoglycemia) is low when Jardiance is used on its own, unlike insulin or certain older medications.
How Jardiance Actually Works
Your kidneys filter about 180 grams of glucose from your blood every day. Normally, a transporter protein in the early part of the kidney tubule recaptures about 97% of that glucose and sends it back into the bloodstream. Jardiance blocks that transporter, so a significant portion of the glucose passes through and leaves your body in urine instead. It’s a fundamentally different approach from medications that increase insulin production or improve insulin sensitivity.
Because the drug works through the kidneys rather than through insulin, its blood sugar lowering ability depends on kidney function. In people with reduced kidney filtration rates (below about 45 mL/min), the A1C benefit shrinks because less glucose is being filtered in the first place. That said, Jardiance is still recommended for kidney protection in people with chronic kidney disease, even when the blood sugar effect is reduced.
Benefits Beyond A1C
The glucose your body flushes out carries calories with it. In 24-week clinical trials, people on 10 mg lost an average of 2.8% of their body weight, while those on 25 mg lost about 3.2%. For someone weighing 200 pounds, that translates to roughly 5.6 to 6.4 pounds. It’s not dramatic weight loss, but it’s consistent and happens without any changes to diet or exercise.
Blood pressure also tends to drop. Studies show Jardiance lowers 24-hour systolic blood pressure by about 3 to 4 points on average. Again, modest on paper, but meaningful when combined with the other metabolic improvements.
The cardiovascular data is where Jardiance really stands out. In a landmark trial of people with type 2 diabetes and existing heart disease, Jardiance reduced the risk of cardiovascular death by 38% compared to placebo. That result was striking enough to reshape how diabetes treatment guidelines are written. The American Diabetes Association now recommends SGLT2 inhibitors like Jardiance for people with type 2 diabetes who have heart disease, heart failure, or chronic kidney disease, regardless of what their A1C looks like. In other words, the heart and kidney benefits are considered important enough to justify the medication even if blood sugar control isn’t the primary goal.
Common Side Effects
The most well-known side effect is genital yeast infections, a direct consequence of having extra sugar in your urine. In clinical trials, about 5 to 6% of women on Jardiance developed genital yeast infections, compared to 1.5% on placebo. For men, rates were 1.6 to 3.1% on the medication versus 0.4% on placebo. These infections are treatable and usually not severe, but they can be recurring and uncomfortable.
Urinary tract infections also occur at slightly higher rates. Staying well hydrated helps reduce the risk of both types of infection.
A rare but serious concern is diabetic ketoacidosis (DKA), a condition where the body produces dangerously high levels of ketones. In people with type 2 diabetes, the estimated incidence is low, roughly 0.6 to 4.9 events per 1,000 person-years. The risk is higher in people who eat very low-carb or ketogenic diets, are dehydrated, or have reduced insulin production. Symptoms include nausea, vomiting, abdominal pain, and unusual fatigue. What makes Jardiance-related DKA tricky is that blood sugar levels may appear normal or only mildly elevated, so it can be missed if you’re only checking glucose.