7 Signs Metformin Is Working: A Guide for Women

The most reliable signs metformin is working are steadier blood sugar, a falling A1c, fewer cravings, and more consistent energy. But those are big promises, right? If you’re new to metformin and just started taking it, you may not notice any changes right away. That's because the medication works gradually, and the benefits from steadier blood sugar and overall metabolic health can take time.

Let’s back up a bit: Metformin is a medication that helps your body respond better to insulin, which in turn helps keep blood sugar levels steady. Because of that, metformin can be prescribed for a few different reasons, from type 2 diabetes to off-label uses like polycystic ovary syndrome (PCOS, now known as polyendocrine metabolic ovarian syndrome, or PMOS) or mild weight loss. What “working” looks like depends on why you’re taking metformin in the first place. 

If you’re taking metformin (or will be starting it soon), it’s helpful to learn the key signs to watch for so you’ll know that the medication is working, how long it takes to work, and what to discuss with a clinician (like one at Midi) if metformin doesn’t appear to be doing enough for you. 

What Is Metformin and How Does It Work?

Metformin is an FDA approved medication for type 2 diabetes. It’s also commonly prescribed off-label to manage a range of conditions, including:

• prediabetes
• gestational diabetes
• PCOS
• mild weight loss

Metformin can also be prescribed during the menopause transition to help offset the rise in insulin resistance that can occur during perimenopause and menopause. 

So how does metformin work? In short, metformin improves insulin sensitivity, decreases insulin resistance, and reduces the amount of glucose your body produces. Overall, you should see steadier blood sugar levels overall, as well as after eating.

That’s not only a boon for your blood sugar. By reducing insulin levels, ovarian androgen levels also decline. Regulating hormones in this way can help to restore more regular ovulation and menstrual cycles if you have PCOS.

Although metformin is a widely used, effective medication, results don’t happen overnight. Improving insulin sensitivity or hormonal regulation takes time—and a healthy lifestyle, too.

7 Signs Metformin Is Working

Metformin targets metabolic pathways, so you should see improvements in your lab numbers and certain high blood sugar symptoms. Here are a handful of signs metformin is working:

1. Blood sugar changes 

Regular lab work will reveal your blood sugar control. Clinicians primarily focus on a reduction in hemoglobin A1c (HbA1C), a measure of your average blood sugar level over the past 3 months. If you have diabetes, the A1c goal is typically 7% or less. 

2. Gradual weight loss 

Metformin is not a weight loss drug, so when it’s used for this purpose, it’s considered off-label rather than a first-line treatment. Still, it may lead to modest and gradual weight changes. For example, one study including approximately 3,200 people found that one-third of them lost at least 5% of their body weight during their first year taking metformin—and many of them kept this weight off long-term (the study looked at how they were doing 6 to 15 years later). More broadly, many people with diabetes lose around 2% to 3% of their body weight within the first year of starting metformin.

3. Reduced appetite

Some people who take metformin notice a reduced appetite, which can reduce the number of calories you eat. The medication may do this by affecting appetite hormones in the gut that communicate with the brain, among other possible physiologic effects. If you feel as if you have a better handle on your food choices and intake while taking metformin, the medication may be giving you an assist.

4. Menstrual regularity 

A hallmark symptom of PCOS is irregular or missed menstrual periods. If you’re taking metformin to manage PCOS and your cycle is becoming more regular and predictable, that’s a strong sign metformin is working for PCOS.

5. Decreased inflammation 

One of the benefits of metformin is that the drug has anti-inflammatory properties, which is a reason why it’s being looked at for treating inflammatory conditions. Blood testing for inflammatory blood markers, such as decreased ESR (erythrocyte sedimentation rate) value, can help reflect this. 

6. Reduced risk of disease progression 

Research indicates that metformin can reduce the odds of prediabetes progressing to full-blown type 2 diabetes by 35%. Diabetes can take years to develop, so the sooner you start taking metformin, the easier it can be to manage your glucose level.

7. Fewer symptoms of high blood sugar

Increased thirst and hunger, frequent urination, fatigue, and moodiness are some symptoms of diabetes. These all happen due to uncontrolled blood sugar. With better blood sugar management on metformin, you may start to see an improvement in these symptoms.

How Long Does It Take for Metformin to Work?

It depends on what specific benefits you’re honing in on. After you start taking metformin, the medication will reach peak levels in your bloodstream in 24 to 48 hours. 

Dose and formulation can both affect how quickly and well metformin works to lower your blood sugar. Unlike insulin, metformin doesn’t cause a sudden drop—rather, its glucose-lowering effects build gradually. Research suggests that blood glucose levels typically begin falling within the first 1 to 2 weeks of treatment, with continued reductions as your dose is increased over time.

Because A1c is a measure of your blood sugar over months, you’ll get a more accurate understanding of how well metformin is working for you if you wait 2 or 3 months to check your A1c. That said, your clinician may recommend checking A1c or other blood sugar labs earlier to make sure your numbers are improving. 

Clinicians often initially prescribe metformin at a lower dose to limit gastrointestinal (GI) side effects and increase from there. How well you’re tolerating metformin and how well you can get to a maintenance dose will also affect your results. When blood sugars are better managed consistently, your metabolic health will begin to improve.

Using metformin with healthy lifestyle habits can make a huge difference. And the bigger the changes, the bigger the potential benefit. For example, if you weren’t exercising before and now walk daily and do resistance exercise twice weekly, you might be pleasantly surprised at what your blood sugar numbers are showing. Same goes with what you eat—if you’ve started eating a more balanced diet (such as a Mediterranean diet), you may also be pleased at your glucose levels.

Which Lab Tests Show Metformin Is Working?

Several lab tests can provide insight into your metabolic health and help monitor diabetes. Lab tests used for type 2 diabetes, prediabetes, and gestational diabetes are:

• A1c (your average blood sugar levels over a few months) 
• fasting blood sugar (your level when you wake up in the morning)
• glucose tolerance test (how your blood sugar responds to a super-sugary liquid)
• blood sugar testing (can occur any time for type 2 diabetes)

Your clinician will provide clear guidance on when to do follow-up labs to check that your numbers are moving in the right direction. Generally, they pay most attention to whether your readings show a downward trend toward healthier blood sugar levels, rather than focusing on a single reading alone. If you use a home glucose monitor or wear a continuous glucose monitor, you can track your trends, too. The goal is to aim for steadier overall readings and minimize large post-meal blood sugar spikes.

One quick side note: Metformin can interfere with how your body absorbs vitamin B12, an important nutrient for energy levels. (Low levels can cause a type of anemia.) But these numbers are usually pretty low: In long-term studies, low B12 occurred in about 4.3% of people taking metformin compared to 2.3% taking a placebo at 5 years, with risk increasing the longer someone stays on the medication. Your clinician may recommend a cobalamin (B12) test (a blood test to check B12 levels) annually or more often as needed.

Signs Metformin Is Working for PCOS

Metformin can be prescribed off-label to treat PCOS. Insulin resistance drives many PCOS symptoms, and improving insulin sensitivity can help regulate the menstrual cycle and ovulation, as well as reduce more serious long-term health risks associated with PCOS.

If you have the condition, look for signs metformin is working for PCOS, like: 

• more regular and predictable menstrual cycles with ovulation (cycle regularity can take several months to improve)
• improvement in acne (some research shows this happens after 12 weeks)
• reduction in unwanted hair growth
• potential help with gradual weight loss

Metformin in Perimenopause and Menopause: What Women Should Know

As you head into midlife—and the years of perimenopause and menopause—your estrogen levels are going to shift significantly. Estrogen levels gradually decline, fluctuating along the way, triggering symptoms of menopause and potentially leading hormonal weight gain. 

Estrogen protects against type 2 diabetes through its effects on insulin sensitivity and body fat deposition. As menopause approaches, fluctuating estrogen levels can raise your risk of insulin resistance. On top of that, body composition may change and muscle mass declines. And because muscles, which are incredibly metabolically active, soak up and use glucose for energy, this is an important change. Plus, as your body starts to preferentially store fat in your abdomen, an increase in visceral fat is another risk factor for insulin resistance. This is where metformin may come in handy: by helping your body use insulin more efficiently, it can offset some of these shifts happening during the menopausal transition.

Midlife symptoms like fatigue, appetite shifts, and weight changes can overlap with high blood sugar and menopause, so it can be more challenging to go by “how you feel” alone when gauging whether metformin is working. Blood labs will provide the data you need to stick with treatment, adjust, or move on to something else.

It’s possible that some symptoms are menopause related (or not related to menopause or insulin at all!). Talk with a healthcare professional about your symptoms, including those that are new or changing, rather than attributing every issue to blood sugar. They may recommend additional treatments alongside metformin. 

Clinician-guided care from a menopause-trained clinician, like one at Midi, is the best way to get a well-rounded metabolic health or weight loss plan suited to your specific life stage and symptoms. 

Signs Metformin Is Not Working for Blood Sugar Control 

Not everyone sees the changes described above, which can be incredibly discouraging. If that’s you, you might notice signs metformin is not working, like persistently high glucose readings despite medication treatment, an A1c that’s not improving after a few months, or symptoms of diabetes or insulin resistance that haven’t let up. 

The stalled—or not started—progress can occur for many reasons, including: 

• Your dose is still being adjusted
• Your lifestyle habits haven’t changed
• You’re not taking it as prescribed

Just know that it’s not always a reflection of what you’re doing (or not doing). Not everyone who takes metformin will respond to it. In one study on a diverse U.S. population, 43% of people were categorized as metformin non-responders, defined as not reaching an A1c goal of less than 7% within 18 months of treatment or starting another drug with metformin. Those whose A1c was higher at the start of metformin were more likely to not fully respond to the medication.  

What to Do if Metformin Is Not Working for Blood Sugar Control

If metformin is not working, you still have many options—and your clinician will guide you on the right path for you. Options include: 

• adjusting your metformin dose or formulation
• taking a lifestyle “audit” and reinforcing healthy habits (like sleep, nutrition, and exercise)
• switching medications (such as to a GLP-1, for instance)
• referring you to a primary care provider or endocrinologist (if you have type 2 diabetes that requires more intensive, specialized management)

Follow-up visits are the perfect chance to talk about your progress or concerns. You can ask any questions that you feel are most important, but here are some to get your brainstorm going:

• What are my current blood sugar numbers?
• What is my blood sugar goal?
• When should we recheck labs?
• How do we know if metformin is successful for me?
• What are other things I can be doing to improve my numbers and symptoms?

For care that acknowledges the challenges of midlife hormonal change and how that influences your health, Midi’s clinician-led approach can be a supportive next step to address your metformin response, hormones, and weight together. 

Key Takeaways

• Metformin is an FDA-approved medication for type 2 diabetes. It’s also commonly prescribed off-label to manage prediabetes, gestational diabetes, weight concerns, and PCOS.
• Metformin improves insulin sensitivity, decreases insulin resistance, and reduces the amount of glucose your body produces. 
• The most reliable signs metformin is working are steadier blood sugar, a falling A1c, fewer cravings, and more consistent energy. 
• Signs metformin is not working are persistently high glucose readings, an A1c that’s not declining after a few months, or symptoms of diabetes or insulin resistance that haven’t improved.
• A clinician-led approach can be a supportive next step to address your metformin response, hormones, and weight together. 

Frequently Asked Questions (FAQs)

Does metformin lower blood sugar?

Yes. Metformin lowers blood sugar by improving your body’s insulin sensitivity, decreasing insulin resistance, and reducing the amount of glucose your liver makes. Altogether, these effects can lead to steadier blood sugar levels, both while fasting and after meals.

What happens if you eat a lot of sugar while taking metformin?

Metformin works by decreasing glucose production in the body, reducing glucose absorption, and improving insulin sensitivity. If you eat a lot of sugar, your body will be better equipped to process that extra glucose if you’re taking metformin. However, if you have diabetes, experts do not recommend eating large amounts of sugar. Stick to a plant-based, high-fiber diet that limits added sugar.

What should you avoid eating while on metformin?

If you have type 2 diabetes or insulin resistance (prediabetes or PCOS), following the Diabetes Plate method is a good goal. Fill half your plate with non-starchy vegetables, one-quarter with carbohydrate foods (like starchy vegetables or fruits), and one-quarter with protein foods. Pair your meals with a zero-calorie drink, primarily water.

Can I eat eggs with metformin?

Yes, eggs are considered a lean protein food and are a type of protein that the American Diabetes Association recommends including in your diet if you’d like.

Is metformin a GLP-1?

No, it’s not that type of medication. Metformin is an oral anti-diabetic medication. Like certain GLP-1 medications, such as semaglutide (Ozempic), metformin treats type 2 diabetes because it improves blood sugar management. However, both medications are in different classes and work in unique ways. 

Does metformin cause hair loss?

Not typically. The most common side effects of metformin are low blood sugar, diarrhea, and nausea. Hair loss is not a listed side effect. Since metformin introduces a risk of B12 deficiency, and B12 deficiency has been associated with hair loss, there may be an indirect link for some people, but this is not expected.