Metformin (Glucophage) is first line therapy for diabetes which carries the benefit of helping with weight loss. It’s cheap, does not result in risky low blood sugars (hypoglycemia), has a cheap generic—oh AND it may help you live longer. In a previous blog I told you about the exciting early evidence that metformin may help prevent aging.
Well, a recent loosening of restrictions from the FDA means that 40% or 50% of patients with type 2 diabetes who have mild-moderate chronic kidney disease (CKD) will now be eligible to take metformin.
- Labeling of metformin and metformin-containing drugs (Janumet, Metaglip, Glucovance) will be changed to show that they are safe to use for people with mild to moderate renal (kidney) impairment. This is great because many diabetics have kidney disease and this opens up metformin use for you.
- Instead of your doctor measuring just a creatinine blood test for your kidney function, your doctor can do tests to estimate your GFR (glomerular filtration rate) which takes into account your age, gender, race and/or weight. Just so you know, this is easily done with a GFR calculator where you enter blood creatinine (Cr) and other factors and get the GFR number back.
- Now, before starting metformin, your doctor will estimate your GFR instead of your creatinine. The restrictions now: If you have a GFR lower than 30 mL/min, which is severe kidney disease (stage 4 or higher), you should still not use metformin. It’s also not recommended that you start metformin if you have stage 3 chronic kidney disease (GFR 30-45).
- Your doctor should do a GFR check once a year if you are taking metformin.
- One other change: before, everyone taking metformin had to stop taking it prior to imaging studies like a CT scan. Now, it’s only recommended you stop taking metformin before certain imaging procedures if your GFR is between 30 and 60 mL/min—or if you have a history of liver disease, alcoholism, or heart failure. If you do need to stop taking it for a CT scan or other imaging, you can restart 48 hours after the procedure as long as your kidney function is stable.