Despite its common association with type 2 diabetes, you may have heard about people with type 1 diabetes being prescribed metformin off-label and be wondering about its safety and how the prescription drug works for people with type 1.
This article will investigate the use of metformin for type 1 diabetes and will answer some common questions you might have about using metformin as a person with type 1 diabetes.
Why would someone with type 1 diabetes want to take metformin?
People with type 1 diabetes may be prescribed metformin off-label (not approved by the FDA) for assistance with insulin resistance, to help better manage their blood sugar levels, and in some cases for weight loss (usually as a result of insulin resistance as well).
Several clinical trials and meta-analyses have established that taking metformin can lead to modest weight loss. Though this isn’t the most common reason people have prescribed metformin, the drug is known to reduce appetite and help the body be slightly more metabolically efficient, which can lead to weight loss over time.
Even though trials have shown that A1c levels do not change significantly for people with type 1 diabetes who start taking metformin, research has found that adding metformin to an existing insulin regimen does reduce the amount of insulin people need to take each day.
For people with type 1 diabetes, metformin is always used in conjunction with insulin therapy.
Can metformin replace insulin?
It is not safe for people with insulin-dependent diabetes to attempt to replace insulin with metformin.
Management of type 1 diabetes requires insulin therapy. This is because if you have type 1 diabetes, your pancreas produces no insulin.
Metformin can significantly help lower blood sugar levels, but it doesn’t increase or restore the body’s ability to produce insulin.
It’s important to consult with your doctor about medications you’re taking to make sure your prescriptions and plan of care are up-to-date and to help prevent unintended interactions – but metformin will not allow people with type one diabetes to stop taking insulin.
Is taking insulin better than taking metformin?
There is no superiority between insulin and metformin. Rather, they work in different ways that can be complementary in some cases.
There are also many kinds of insulin, all of which are injected or administered subcutaneously (under the skin) by an insulin pump – or in the case of Afrezza, inhaled.
As a general matter, insulin helps to bring down your blood sugar levels faster than metformin can.
Metformin helps you manage your blood sugar levels, can fight insulin resistance, and can even help you lose weight.
But there are also downsides to both metformin and insulin.
Metformin can cause stomach discomfort, diarrhea, and other digestive issues, especially if the dose is too large or if you take it on an empty stomach.
Insulin is a powerful hormone, and taking too much insulin can cause low blood sugar (hypoglycemia), which can be very dangerous if untreated.
Clinical trials over many years have established that when metformin alone is insufficient to manage blood sugar levels for people with type 2 diabetes, combining it with insulin therapy is an effective way to improve control as measured by A1c.
Again, insulin therapy is necessary for people with type 1 diabetes, while metformin therapy is not.
However, because metformin and insulin work differently, there are reasons why researchers are now exploring metformin’s potential usefulness among people with type 1 diabetes.
What happens when a person with type 1 diabetes takes metformin?
In 2017, a meta-analysis published in the journal Diabetologia showed that over 15% of adults with type 1 diabetes in Scotland had been prescribed metformin. In France, metformin has an indication for type 1 diabetes in addition to type 2.
The analysis, entitled “A New Perspective on Metformin Therapy in Type 1 Diabetes,” neatly summarizes it this way:
“Perhaps because of such compelling evidence in type 2 diabetes, off-label use of metformin in type 1 diabetes is quite common in clinical practice.”
The research found that people with type 1 diabetes who took metformin in addition to insulin experienced a significant reduction in the amount of insulin they needed to take each day (a nearly 7 unit per day reduction) once metformin was added.
Subsequent research in 2018 reinforced these findings, showing net benefits for people with type 1 diabetes who add metformin to their existing insulin regimen. Adding metformin was again shown to help with weight management, it decreased daily insulin needs and slightly improved blood pressure.
While there were also some minor improvements in average blood sugar levels, these changes were not significantly different from a placebo group.
Except for gastrointestinal upset, there were no serious metformin side effects reported from these studies.
Finally, as noted by Dr. Leon Gussow in Emergency Medicine News, metformin has been having a moment in the spotlight in recent years due to its hypothesized benefits for cardiovascular health, inflammation-reduction, and improvements in all-cause mortality.
Dr. Gussow is quick to note, though, that the evidence base here is in mice and other test animals – not in humans.
Nonetheless, this off-label use for purported general health benefits appears common and can be especially helpful for people living with type 1 diabetes who are already at a heightened risk for heart disease, stroke, and premature death.
As with all prescription drugs, metformin should only be taken under the guidance of a doctor or other medical professional, and your medical history and health goals will have a significant bearing on whether or not a metformin prescription is likely to be helpful.
Frequently asked questions
There is limited evidence that taking metformin may extend lifespan, but significant clinical trials are underway to learn more. One of the largest trials working to establish a fact base about metformin’s effects on aging and longevity is known as TAME (Targeting Aging with Metformin).
For now, not enough is known about the effects of metformin on life expectancy to judge, and this is true for people with type 1 diabetes and without.
At least until more is known, it’s safe to rely on general guidance from your doctor to improve health, including keeping your blood sugar levels in range, eating a healthy diet, getting enough exercise, managing stress, and avoiding risky behaviors like smoking cigarettes.
Because insulin therapy is absolutely necessary for people living with type 1 diabetes, metformin is usually considered to be optional, and its clinical evidence base is not as robust as it is for the treatment of type 2 diabetes.
No, unlike insulin which starts to lower blood sugar very quickly, metformin generally takes 2-5 days to lower average blood sugar levels.
Some people will not notice effects from metformin for as long as two weeks after starting the drug, and some will never see any effect at all.
If you stop taking metformin, the drug will stay in your system for about 4 days, so it’s important to be aware that you may have to adjust your insulin doses when you start or stop taking metformin.
Many of these drugs have not been tested extensively in people with type 1 diabetes, so it’s important to talk with your doctor or other medical professionals to understand what treatment options are safe and likely to be effective.
Because the pancreas of a person with type 1 diabetes cannot produce insulin, these medications are not effective – and therefore, metformin combination drugs would not have a benefit for a person with type 1 diabetes.
There are plenty of conditions and circumstances that might warrant taking metformin even if you don’t have diabetes. These include conditions like PCOS, or a need to lose weight that a doctor believes might be aided by metformin.
Beyond that, many clinical trials are still ongoing to determine if there are health benefits for otherwise healthy people to take daily metformin.
While tests in animals show some improvements in cardiovascular health, inflammation, and decreases in all-cause mortality, these findings are so far tentative and have not been widely demonstrated in people yet.
Though metformin is generally understood to be quite safe, it’s important to recognize that it does carry some risk of side effects. Metformin can cause upset stomach, vitamin B-12 deficiency, hypoglycemia (low blood sugar), and very rarely – though most seriously – lactic acidosis.
For these reasons, it’s always important to work with your doctor and medical care team to understand the risks and benefits of metformin before taking it.