Metformin is a well-known diabetes medication used to help manage blood sugar levels, most often for people with prediabetes, gestational diabetes, and type 2 diabetes. It's often used as a first line of defense for helping people achieve better glycemic control.

Although metformin is primarily used to treat diabetes, its benefits reach well beyond blood sugar management. In this article, you’ll learn the surprising advantages of metformin for people without diabetes, including its potential to support fertility and even enhance longevity, along with some notable side effects to consider.

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What Is Metformin?

Metformin is an oral prescription medication most commonly used to treat type 2 diabetes. Developed in the 1920s and finally approved for use in the 1990s, metformin belongs to a class of drugs known as biguanides. It reduces the amount of sugar the liver releases into the bloodstream and increases the body's sensitivity to insulin. Since metformin improves insulin sensitivity, it's generally not used for people with type 1 diabetes, who rely on insulin injections to manage their blood sugar levels. However, it may be prescribed alongside insulin in certain cases to help enhance insulin sensitivity in those with type 1 diabetes.¹

Whether prescribed alone or alongside other medications, metformin is incredibly effective at helping to manage blood glucose levels. Beyond its use as a diabetes medication, metformin has gained popularity as a treatment for many other areas of health as well. 

How Does Metformin Work?

Metformin’s effectiveness in managing blood glucose levels comes from its unique ability to improve the body's handling of insulin. 

Metformin primarily reduces the amount of glucose produced by the liver and the amount your stomach and intestines absorb from the food you eat. Instead of increasing the amount of insulin the pancreas produces, it improves the insulin sensitivity of your cells, helping your body more effectively use the insulin it already produces. This dual action helps prevent the spikes in blood sugar that can be harmful over time, making metformin an effective tool to reduce the negative effects of high blood sugar.¹

Benefits of Metformin Beyond Diabetes

Although metformin is primarily prescribed as a diabetes treatment, research suggests it may offer additional, off-label benefits for people with or without diabetes. Beyond its beneficial effects on metabolic health, metformin may positively impact a number of body systems, with potential benefits ranging from weight loss and cancer prevention to improved fertility.

Prediabetes

Metformin is often used to help prevent the progression of prediabetes to type 2 diabetes when lifestyle changes may not be enough. Prediabetes can often be reversed, but if not, it can lead to type 2 diabetes, heart disease, and stroke. Metformin helps reverse prediabetes, much like it treats diabetes by increasing insulin sensitivity and reducing glucose production in the liver. Research shows that metformin can lower the risk of prediabetes progressing to type 2 diabetes by 35 to 42 percent, making it a highly effective tool for maintaining better metabolic health.^{2, 3}

Fertility

Insulin resistance is a common feature of polycystic ovary syndrome (PCOS) and can lead to menstrual cycle dysfunction, including missed ovulation, infertility, and an increased risk of miscarriage. Metformin has been shown to regulate menstrual cycles and enhance fertility, particularly in women with PCOS. Additionally, metformin may improve fertility in men with metabolic syndrome by boosting testosterone production.^{4, 5}

Lower Cholesterol

Metformin may help reduce the progression or development of high cholesterol in people with type 2 diabetes, effectively reducing the risk of heart disease. A meta-analysis of clinical trials has found that metformin may help lower total cholesterol,  LDL cholesterol, and triglycerides.⁶

Longevity

Some studies suggest that metformin may contribute to longevity by reducing inflammation and improving metabolic health, even in people without diabetes. While current research doesn’t confirm that metformin directly extends the lifespan, its positive effects on lifestyle and age-related diseases like diabetes, cardiovascular disease, and cancer could help increase the number of healthy years lived.⁷

Weight Loss

Metformin is not officially approved as a weight loss medication, but research suggests it may support weight loss for people with a body mass index (BMI) categorized as overweight or obese. One small study found that patients with obesity who took metformin lost an average of 6.5 percent body weight after six months of metformin treatment, regardless of whether they had type 2 diabetes or not. Its effectiveness in weight reduction is likely due to its ability to improve insulin sensitivity and reduce appetite.^{8, 9}

Cancer Prevention

Recent research suggests that metformin therapy may lower the risk of developing cancers such as colon, pancreatic, and liver cancer while also enhancing the effectiveness of treatments like chemotherapy and radiation therapy thanks to its ability to inhibit cell growth and prevent tumor development. In one large population study, people with diabetes who took metformin had a reduced risk of all cancers compared to those using sulfonylureas, another commonly prescribed oral diabetes medication.^{10, 11}

Dementia

Insulin resistance in the brain is associated with an increased risk of developing Alzheimer’s Dementia. Through its ability to combat insulin resistance, metformin may reduce the risk of dementia, although studies have found that the dose of metformin may be an important factor to consider. 

One large study found that people who took low doses of metformin had a decreased risk of developing dementia over a three and five-year period. In contrast, those taking higher doses did not see the same benefit. Some of the negative cognitive effects of high doses of metformin may be related to nutrient deficiencies, which can be caused if not addressed.^{12, 13}

<div class="pro-tip"><strong>Also Read: </strong><a href=signs-metformin-is-working>How Long Does Metformin Take to Work? 6 Signs to Look For</a></a>.</div>

Side Effects Of Metformin

While metformin is a generally well-tolerated and safe diabetes drug, it can cause some undesired side effects, including gastrointestinal effects, which impact up to 30 percent of people taking it. Some of the most common side effects include:¹⁴ 

• Diarrhea: Many people experience gastrointestinal issues, with diarrhea being the most frequently reported side effect of metformin.
• Nausea: Along with diarrhea, nausea is common, particularly when starting the medication. 
• Dysgeusia: A metallic taste or other changes in taste can occur when taking metformin, as it can accumulate and be excreted through the salivary glands.¹⁵
• Headache: Some people may experience headaches as their body adjusts to metformin.
• Heartburn: Metformin can sometimes cause a burning sensation in the chest or throat, known as heartburn, due to irritation of the gastrointestinal lining and delayed stomach emptying.¹⁶
• Muscle Pain: In some cases, metformin users report muscle pain or discomfort, which can vary in intensity.
• Vitamin B12 Deficiency: Long-term use of metformin has been linked to decreased vitamin B12 levels, which may lead to symptoms like fatigue, weakness, and cognitive effects if not addressed with supplementation.¹⁷

These side effects are usually mild and often improve as the body gets used to the medication. A very serious but rare side effect is metformin-induced lactic acidosis (MALA). MALA occurs when there’s too much acid in the blood, which can be life-threatening. If you experience any side effects of metformin, it's important to consult with your diabetes care provider to decide if metformin is the best treatment option for your needs. 

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<div class="pro-tip"><strong>Learn More: </strong><a href=foods-to-avoid-while-taking-metformin>6 Foods You Should Avoid While Taking Metformin</a>.</div>