Invokana (canagliflozin) lowers blood sugar by forcing your kidneys to flush excess glucose out through urine instead of reabsorbing it back into the bloodstream. It belongs to a class of drugs called SGLT2 inhibitors, and beyond glucose control, it also offers measurable protection for the heart and kidneys.
What Happens in Your Kidneys
Your kidneys filter about 180 grams of glucose from your blood every day. Normally, almost all of it gets reabsorbed back into the bloodstream through a protein called SGLT2, which sits on the inner surface of tiny tubes (proximal tubules) in the kidney. SGLT2 pulls glucose and sodium together from the filtered fluid back into kidney cells, and from there the glucose crosses into the blood on the other side.
Invokana blocks that SGLT2 protein. When it binds to SGLT2, glucose can no longer be pulled back into kidney cells, so it stays in the urine and leaves the body. This process also reduces sodium reabsorption at the same site, which lowers the energy demands on kidney cells and contributes to a modest drop in blood pressure. The overall effect is straightforward: your body disposes of extra sugar rather than recycling it.
How Much It Lowers Blood Sugar
In FDA clinical trials, the lower dose (100 mg daily) reduced HbA1c by about 0.9 percentage points more than placebo when used alone, and the higher dose (300 mg) reduced it by roughly 1.2 points. Those are meaningful drops for a single medication. When added on top of metformin, the reductions were smaller but still significant: around 0.6 to 0.8 points depending on dose.
The drug works regardless of insulin levels, which is a key distinction from many other diabetes medications. Because it targets the kidney rather than the pancreas, it doesn’t depend on your body producing or responding to insulin. That said, its blood sugar effect weakens as kidney function declines, since less glucose is being filtered in the first place. Invokana is not recommended for improving blood sugar control in people whose kidney filtration rate (eGFR) falls below 30.
Weight Loss and Blood Pressure Effects
Because you’re literally excreting calories in your urine, Invokana produces consistent weight loss. Across pooled clinical data, patients lost an average of about 3.3% of their body weight compared to placebo, and that reduction held for at least a year regardless of dose. For someone weighing 220 pounds, that translates to roughly 7 pounds.
Systolic blood pressure also drops by an average of 4.4 mmHg compared to placebo. This comes partly from the sodium loss at the kidney and partly from a mild diuretic effect. Neither the weight loss nor the blood pressure reduction requires any additional medication or lifestyle change on top of taking the pill.
Heart and Kidney Protection
Invokana’s benefits extend well beyond blood sugar numbers. In the CANVAS trial program, which enrolled over 10,000 people with type 2 diabetes and high cardiovascular risk, canagliflozin reduced the combined risk of heart attack, stroke, or cardiovascular death by 14%. Among patients with established heart disease, that reduction was 18%.
The kidney data is even more striking. The CREDENCE trial, the first major kidney outcomes trial for any SGLT2 inhibitor, found that canagliflozin reduced the risk of end-stage kidney disease (meaning dialysis or transplant) by 32%. The broader kidney endpoint, which included doubling of creatinine levels, dropped by 34%. These results were significant enough to prompt the American Diabetes Association to update its treatment guidelines. For patients who already have substantial protein in their urine (a sign of kidney damage), Invokana can be continued at 100 mg specifically for kidney protection even when kidney function is reduced.
Common Side Effects
The most frequent side effect is genital yeast infections, a direct consequence of sugar-rich urine creating a favorable environment for fungal growth. In clinical trials, about 10.6% of women on the 100 mg dose developed genital yeast infections compared to 2.8% on placebo. For men, the rate was 4.2% versus 0.7% on placebo. These infections are treatable with standard antifungal medications, but they can recur.
Urinary tract infections are also more common. Increased urination and mild dehydration are expected effects of the drug’s mechanism, so staying well hydrated matters. Some people experience lightheadedness when standing up, particularly early in treatment or if they’re already taking blood pressure medications.
A Rare but Serious Risk: Ketoacidosis With Normal Blood Sugar
SGLT2 inhibitors carry a small risk of a condition called euglycemic diabetic ketoacidosis. This is a dangerous buildup of acid in the blood that normally occurs alongside very high blood sugar, but with Invokana, it can happen even when blood sugar readings look normal or only mildly elevated (under 200 mg/dL). That’s what makes it tricky: the usual warning sign of sky-high glucose is absent.
Symptoms include nausea, vomiting, abdominal pain, fatigue, and difficulty breathing. If you’re on Invokana and develop these symptoms, a normal reading on your glucose monitor does not rule out this condition. Ketone testing (urine strips are available over the counter) is the better check. Situations that increase risk include surgery, prolonged fasting, illness, heavy alcohol use, or a very low-carb diet. Invokana is typically paused before planned surgeries and during acute illness for this reason.
How Dosing Works in Practice
Invokana is taken once daily before the first meal. Most people start at 100 mg, and the dose can be increased to 300 mg for additional blood sugar control. Kidney function determines whether you can take it: initiation is not recommended if your eGFR is below 30. However, if you’re already on it and your kidney function declines, you may be able to continue the 100 mg dose for its heart and kidney protective benefits, particularly if you have significant protein in your urine.
The blood sugar lowering effect begins within the first day, though the full impact on HbA1c takes weeks to manifest in lab results. Weight loss and blood pressure changes also develop gradually over the first several months before stabilizing.