By Dr. Sharon Oorange
Is metformin bad for you? There is quite a bit of misinformation out there about this popular medication. Metformin therapy may cause diarrhea and lower vitamin B12 levels, but most things you hear about metformin aren’t true. Here are 10 Big Myths about Metformin.
1) Metformin is bad for your kidneys.
It’s not. There may be some confusion here because up until 2016, patients with higher creatinine levels—a potential sign of kidney dysfunction—were advised not to take metformin. But metformin, in fact, does not cause kidney problems, and that recommendation has since changed. Now, labels for metformin say that only patients with late-stage chronic kidney disease (stage IV or V) should not use the medication.
2) Metformin is bad for your liver.
The truth is, in the vast majority of cases, it’s not. The liver isn’t involved in processing and metabolizing metformin at all. Instead, metformin leaves the body unchanged in the urine. Metformin could actually be beneficial to patients with certain liver diseases.
Still, liver injury due to metformin is a very rare, but possible, reaction. Patients who experience this reaction have usually used metformin for 4 to 8 weeks at the same time as using other medications that can damage the liver.
3) Metformin is dangerous to take during pregnancy.
4) Metformin causes dementia.
No. In fact, a recent study of 17,000 veterans with diabetes found that taking metformin was associated with a lower risk of dementia than other diabetes drugs known as sulfonylureas (like glyburide and glipizide). And just this month, a study showed that metformin use was associated with reduced rates of dementia and improved cognitive function among African American patients with type 2 diabetes.
5) Metformin is bad for your heart.
This is one I hear quite a bit from patients, and it’s not true. Studies suggest that metformin exhibits heart-protective effects in the setting of a heart attack. Metformin therapy is also associated with a reduced risk of death and disease in patients affected by both diabetes and heart failure.
6) Metformin causes scary lactic acidosis.
The risk of metformin causing lactic acidosis of the blood is exceedingly rare. A Cochrane systematic review of 70,490 patients with type 2 diabetes on metformin did not report a single case of metformin-induced lactic acidosis. The risk of metformin causing lactic acidosis appears to be no greater than that of non-metformin therapies.
7) Metformin raises cholesterol.
Nope! In fact, metformin has improves lipid (cholesterol) metabolism and lowers LDL cholesterol along with triglycerides.
8) Metformin is bad for the pancreas.
Metformin is not a known cause of acute pancreatitis and lowers (not raises) the risk of pancreatic cancer.
9) Metformin causes cancer.
This is also not true. Metformin appears to be protective. In just one example, the Women’s Health Initiative (WHI) found that metformin was associated with fewer cancer-related death in patients with diabetes. Studies also show that metformin may prevent colorectal polyps from returning after removal. These tiny growths in the colon can turn into cancer, which suggests that metformin may play a protective role in colon cancer.
10) You can’t have a CT scan with contrast when taking metformin.
Intravenous contrast is often given prior to CT scan imaging. In patients with no evidence of acute kidney injury or end-stage kidney disease, there’s no need to discontinue metformin either prior to or following the administration of contrast media. In patients taking metformin who have acute kidney injury or severe chronic kidney disease (stage IV or stage V), metformin should be temporarily discontinued prior to the procedure and withheld for 48 hours after the procedure.
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