When you take metformin, a first-line oral medication for type 2 diabetes that helps lower blood sugar by reducing liver glucose production and improving insulin sensitivity. It's one of the most prescribed drugs in the world, but it's not safe for everyone—especially if your kidneys aren't working well. The link between kidney function, how well your kidneys filter waste and regulate fluid balance, measured by eGFR (estimated glomerular filtration rate) and metformin, a first-line oral medication for type 2 diabetes that helps lower blood sugar by reducing liver glucose production and improving insulin sensitivity isn’t just a footnote—it’s a critical safety rule. If your kidneys can’t clear metformin properly, the drug builds up and can cause a rare but dangerous condition called lactic acidosis. That’s why doctors check your kidney numbers before prescribing it and keep checking them after.
Most people with normal kidney function can take standard doses of metformin—usually 500 to 2,000 mg daily. But if your eGFR drops below 45 mL/min, your doctor will likely reduce your dose. If it falls below 30, they’ll stop it entirely. This isn’t guesswork. It’s based on FDA guidelines and years of real-world data showing how metformin clears from the body. People with mild kidney issues (eGFR 30–44) can still use metformin, but only at lower doses and with more frequent monitoring. And if you’re over 65, have heart failure, or are dehydrated, your risk goes up—even if your eGFR looks okay. That’s why doctors don’t just look at one number. They consider your whole picture: age, other meds, fluid intake, recent illness.
What you’ll find in this collection are real, practical guides on how metformin interacts with kidney health, how to interpret your lab results, what to do if your dose needs changing, and how to stay safe while managing diabetes with reduced kidney function. You’ll see posts that explain how to talk to your doctor about your eGFR, what alternatives exist if metformin isn’t right for you, and how other drugs you take might affect your kidneys or metformin levels. No theory. No fluff. Just clear steps and facts you can use today.
