SGLT2 inhibitors are a class of medications that lower blood sugar by causing your kidneys to flush excess glucose out through urine. Originally developed for type 2 diabetes, they’ve proven so effective at protecting the heart and kidneys that they’re now prescribed for heart failure and chronic kidney disease even in people without diabetes. The most commonly prescribed ones are canagliflozin (Invokana), dapagliflozin (Farxiga), and empagliflozin (Jardiance).
How They Work
Your kidneys filter about 180 grams of glucose from your blood every day, and under normal circumstances, nearly all of it gets reabsorbed back into your bloodstream. A protein called SGLT2, located in the early filtering tubes of the kidney, handles the bulk of that reabsorption. SGLT2 inhibitors block this protein, preventing 30% to 60% of filtered glucose from being reabsorbed. That glucose stays in your urine and leaves your body.
Because this mechanism works independently of insulin, the drugs lower blood sugar without forcing the pancreas to work harder. The result is a typical reduction in HbA1c (a measure of average blood sugar over three months) of 0.5% to 1.0%. That’s a meaningful drop, roughly equivalent to what many other diabetes medications achieve, but with a set of additional benefits that most blood sugar drugs don’t offer.
Benefits Beyond Blood Sugar
The reason SGLT2 inhibitors have reshaped treatment guidelines has less to do with glucose control and more to do with what they do for the heart and kidneys. By blocking glucose and sodium reabsorption together, they reduce fluid volume in the body, lower blood pressure modestly (about 3 mmHg systolic on average), and promote mild weight loss through calorie loss in urine.
The cardiovascular data is striking. Across 13 major clinical trials, SGLT2 inhibitors consistently reduced hospitalizations for heart failure by roughly 30%. In two landmark trials, empagliflozin cut cardiovascular death by 38%, and dapagliflozin reduced it by 18%. That consistency held across a wide range of patients, including those with multiple other health conditions.
For kidney protection, meta-analyses show SGLT2 inhibitors significantly slow the progression of chronic kidney disease and reduce the risk of kidney failure. In one large trial, the risk of kidney disease progression or cardiovascular death dropped by 36% in people with diabetes and by 18% in those without. The kidney benefits appear strongest in people with higher body weight, with the protective effect diminishing in people with a BMI below 25.
Who Should Take Them
Current guidelines give SGLT2 inhibitors a top-tier recommendation (Class 1a) for people with diabetes who also have heart failure, chronic kidney disease, or established cardiovascular disease. For people without diabetes, they carry the same strong recommendation if you have heart failure or significant protein in the urine (a marker of kidney damage).
Your doctor can typically start an SGLT2 inhibitor if your kidney filtration rate (eGFR) is 30 or above. If your kidney function declines after you’ve already started, the medication can usually be continued. It’s only stopped when side effects become problematic or kidney function drops to the point of needing dialysis.
Common Side Effects
The most frequent side effect is genital yeast infections, which makes sense: extra sugar in the urine creates an environment where yeast thrives. The risk is about two to three times higher than in people not taking these drugs, affecting roughly 8% to 10% of users compared to 3% to 5% on placebo. These infections are typically mild and treatable with standard antifungal medications. They’re more common in women but can affect men as well.
Increased urination is expected, since the drugs work by moving more glucose and water through the kidneys. Some people experience mild dehydration, particularly early on or in hot weather, so staying well-hydrated matters. Urinary tract infections occur somewhat more often, though the increase is smaller than with yeast infections.
A Rare but Serious Risk: Ketoacidosis With Normal Blood Sugar
The most important safety concern is euglycemic diabetic ketoacidosis, a condition where the body builds up dangerous levels of acid (ketones) in the blood while blood sugar remains deceptively normal, below 250 mg/dL. In typical ketoacidosis, very high blood sugar serves as a red flag. With SGLT2 inhibitors, that warning sign can be absent, making it easy to miss.
Symptoms to watch for include nausea, vomiting, abdominal pain, unusual fatigue, loss of appetite, and shortness of breath or unusually deep, rapid breathing. Some people notice a fruity smell on their breath. This condition is uncommon but requires emergency treatment. It’s more likely to occur during illness, surgery, prolonged fasting, or significant reductions in food intake, all situations where your doctor may advise temporarily stopping the medication.
What Taking Them Looks Like Day to Day
SGLT2 inhibitors are taken as a single pill once daily, with or without food. Most people notice increased urination in the first few weeks, which tends to become less noticeable over time. The modest weight loss, typically a few pounds, comes from the calories lost through glucose in urine rather than from appetite suppression, and it generally stabilizes within the first few months.
Because the drugs lower blood sugar without depending on insulin levels, the risk of hypoglycemia (dangerously low blood sugar) is low when used alone. That risk increases if you’re also taking insulin or certain other diabetes medications, so dose adjustments to those drugs may be needed. Good hygiene practices can help reduce the risk of genital infections, and drinking enough water throughout the day helps prevent dehydration-related issues like dizziness or lightheadedness.