Metformin vs. Invokana
See how Metformin and Invokana compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Metformin and Invokana both lower blood sugar in type 2 diabetes, but metformin works mainly in the liver and gut while Invokana works in the kidneys.
Metformin is usually prescribed first because of its long safety record and low cost, while Invokana is often added on or chosen for its heart and kidney benefits.
The two drugs cause different side effects: metformin mainly causes digestive upset, while Invokana raises the risk of genital and urinary infections.
Metformin vs. Invokana Drug Summary
Metformin
Metformin is a biguanide, the first-line oral medication for type 2 diabetes. It lowers blood sugar mainly by reducing how much glucose the liver releases and improving the body's response to insulin. It comes as a tablet or liquid, usually taken with meals once or twice a day, or once daily for the extended-release form.
Invokana
Invokana (canagliflozin) is an SGLT2 inhibitor used to control blood sugar in type 2 diabetes. It works by blocking glucose reabsorption in the kidneys, so extra sugar leaves the body through urine. It is taken as a single tablet once a day, before the first meal, and can also lower cardiovascular and kidney risks in certain patients.
Metformin vs. Invokana Side Effects
Metformin
Invokana
Metformin vs. Invokana Dosage
Metformin
Invokana
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg twice daily | Week 1 |
| Maximum dose | 500 mg once daily | Week 1 |
| Dose changes | 2 increases | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 100 mg once daily | At the start |
| Maximum dose | 100 mg once daily | Same as starting |
| Dose changes | None | Fixed dose |
Metformin
| STAGE | DOSE | WHEN |
| Starting dose | 500 mg twice daily | Week 1 |
| Maximum dose | 500 mg once daily | Week 1 |
| Dose changes | 2 increases | As tolerated |
Invokana
| STAGE | DOSE | WHEN |
| Starting dose | 100 mg once daily | At the start |
| Maximum dose | 100 mg once daily | Same as starting |
| Dose changes | None | Fixed dose |
Metformin vs. Invokana Indications
Metformin
Metformin is FDA-approved to improve blood sugar control in adults and children 10 and older with type 2 diabetes, usually alongside diet and exercise. Doctors also prescribe it off-label for polycystic ovary syndrome and for weight management in people with prediabetes.
Type 2 diabetes in adults (FDA-approved)
Type 2 diabetes in children 10+ (FDA-approved)
PCOS (off-label)
Prediabetes or weight management (off-label)
Invokana
Invokana is FDA-approved as an add-on to diet and exercise to control blood sugar in adults and children 10 and older with type 2 diabetes. It's also approved to lower cardiovascular risk in heart disease and to slow kidney disease in people with diabetic kidney disease.
Type 2 diabetes in adults (FDA-approved)
Type 2 diabetes in children 10+ (FDA-approved)
Lowering CV event risk in heart disease (FDA-approved)
Slowing diabetic kidney disease (FDA-approved)
Metformin vs. Invokana Pros and Cons
Metformin
Metformin has decades of safety data, a low risk of causing low blood sugar on its own, and is the guideline-recommended starting point for type 2 diabetes. It is inexpensive as a generic, though it does not carry FDA-approved cardiovascular or kidney protection claims.
Pros
Decades of real-world safety data as first-line therapy
Low risk of hypoglycemia when used alone
Typically $4 to $30 per month as a generic, before insurance
Simple oral dosing, no injections needed
Cons
Common GI side effects, especially when starting
Boxed warning for rare but serious lactic acidosis
Not usable in severe kidney impairment
No FDA-approved heart or kidney protection claim
Invokana
Invokana carries FDA-approved cardiovascular and kidney protection claims beyond blood sugar control, which metformin does not have. It is a once-daily tablet, but it raises the risk of genital yeast infections and carries its own boxed warning for lower limb amputation.
Pros
FDA-approved to reduce cardiovascular event risk
FDA-approved to slow diabetic kidney disease progression
Once-daily oral tablet
Can modestly reduce body weight and blood pressure
Cons
Boxed warning for increased leg and foot amputation risk
Raises risk of genital yeast infections and UTIs
Rare risk of euglycemic diabetic ketoacidosis
Roughly $550 to $830 per month without insurance, before savings programs
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