Metformin is often the first step in treating high blood sugar levels and insulin resistance. Here are the key points to keep in mind if your doctor has prescribed it.
For those with diabetes and prediabetes, our bodies’ relationship with insulin can be complicated. Fortunately, medications like metformin can help with this connection.
Metformin is a prescription medication that can help moderately decrease blood sugar levels. It works by stopping your liver from producing sugar, while also helping with insulin resistance throughout the rest of the body. Metformin also assists in lowering the glucose that the intestine absorbs from food.
“Metformin not only lowers the blood sugar, but it also helps the body use the insulin that it produces better,” says Dr. Tannaz Moin, assistant professor of endocrinology, diabetes, and metabolism at the David Geffen School of Medicine at UCLA. “That’s why for all these years, metformin has been considered the first-line, go-to medication for [people] with type 2 diabetes.”
If you have a recent diagnosis of diabetes or prediabetes and your doctor prescribed metformin, or if you’re currently discussing treatment options, here are six things to know.
Modern use of metformin actually traces back to an herbal medicine used in medieval Europe called Galega officinalis, also known as goat’s rue or French lilac. The active ingredient in goat’s rue led to the discovery of metformin, which is a less potent and less toxic version of those earlier treatments.
Today, metformin is one of the best known medications for diabetes, having undergone years of research and testing.
“Metformin is one of the oldest, most well studied, and therefore, safest medications we have to treat diabetes,” says Moin. “We have decades and decades of experience using this medication.”
Regulating blood sugar is often a Goldilocks pursuit — we’re constantly looking for levels that are just right, not too high and not too low.
When our blood sugar gets too high, this is called hyperglycemia. Hyperglycemia can happen after eating certain meals or when our bodies don’t use insulin properly.
On the other side of the coin is hypoglycemia. Hypoglycemia is when our blood sugar gets too low. For those who take medications to reduce blood sugar — also called anti-hyperglycemic medications — hypoglycemia is a constant concern.
With metformin, the risk of hypoglycemia is very low. That’s because it generally decreases A1C by about 1% for most people, which isn’t enough to trigger hypoglycemia in most cases.
That being said, it’s still important to be vigilant. Hypoglycemia is a risk when taking anti-hyperglycemic medication, especially for those who drink alcohol frequently or have trouble maintaining balanced diets.
The most common side effects of metformin include gastrointestinal issues, such as nausea, bloating, diarrhea, and vomiting. For most people, these side effects are mild and usually go away over time.
Some people who have been taking metformin for a year or more may also experience a vitamin B12 deficiency, Moin says, so make sure you check your vitamin B12 levels with your doctor roughly once a year.
To counter the possibility of experiencing side effects, most doctors will recommend starting with a smaller dose (around 500 milligrams (mg), for example). Then, doctors prescribe more over the course of several weeks to reach a full dose, which is usually 2,000 mg. It’s also a good idea to take metformin shortly after eating to lessen side effects.
If you experience gastrointestinal issues while taking metformin, there’s also the option to take an extended-release version. By gradually spreading out the effects of the medication, your stomach will have an easier time processing it.
Keep in mind that the severity of side effects also depends on factors like your age, other health conditions, and other medications you’re taking.
In the past, some doctors avoided prescribing metformin because of the risk of lactic acidosis, a serious condition that can occur if metformin builds up in your body and disrupts your pH balance.
In recent years, doctors and the Food and Drug Administration (FDA) have gone deeper into the data and found that metformin is safe for the majority of people, as long as you don’t have significant kidney problems. This is because your kidneys help clear metformin from your system, so if they aren’t working properly, the metformin can accumulate.
Lactic acidosis is also a greater risk if you have liver problems, are over the age of 65, have serious heart issues, or consume moderate to heavy amounts of alcohol regularly.
Moin points out that the FDA has even issued an updated recommendation specifying the levels of kidney function that are cause for concern.
Your estimated glomerular filtration rate (eGFR), which measures the efficacy of your kidney function, should be 45 or higher if you’re taking metformin. If your eGFR is between 30 to 45, the FDA recommends against starting metformin. But if you start metformin and your eGFR later falls below 45, it’s up to your doctor to assess the risks.
Some initial analysis suggests that metformin may have effects on aging, due to its ability to help our bodies regulate blood sugar and use insulin.
But since doctors usually prescribe the medication to people with diabetes, it’s unclear whether lower mortality is due to effectively treating the condition or an additional boost to longevity. More studies need to be done in order to fully understand the effects of metformin on aging and aging-related conditions.
Today, there are many diabetes medications to choose from. Metformin is one of the oldest and most effective, but other treatments and paths exist that may suit your needs better.
The most important thing to remember is that the treatment you choose is ultimately a shared decision between you and your doctor. “It’s really important to sit down with your physician so they know where you’re coming from,” Moin says. “Having those informed conversations is essential.”
Medically reviewed on July 28, 2022
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