Metformin is among the most used diabetes medications used in the United States, with over 92 million prescriptions dispensed in 2020. Despite how commonly Metformin is prescribed, the medicine does not work the same way for everyone. While some people may notice improvements within the first two days of taking Metformin, others may have to wait longer to see any positive change in blood sugar levels or weight.

If you recently started taking this medication, it is normal to feel eager for prompt and visible outcomes. This blog post will highlight how Metformin works in diabetes and how to tell common signs if Metformin is working as intended.

How Does Metformin Work?

Metformin is taken by mouth and regulates blood sugar levels by reducing glucose production in the liver and increasing insulin sensitivity. Metformin is commonly known as Glucophage but has various other brand names, such as Fortamet and Glumetza. The primary role of Metformin is to regulate the excessive release of glucose from the liver into the bloodstream. Doing so helps prevent an unnecessary increase in blood glucose levels. Moreover, Metformin enhances the body's sensitivity to insulin, the hormone the pancreas produces that facilitates glucose utilization for energy.

Metformin can be taken alone or in combination with other diabetes medications, including insulin, to treat type 2 diabetes. It is also found in combination with other antidiabetic agents, such as Sitagliptin (Janumet) and Dapagliflozin (Xigduo XR), among others. This medication, often combined with a healthy diet, exercise, and weight management, can help patients to manage blood sugar levels effectively. It may also be used by people with type 1 diabetes who experience insulin resistance.

Signs Metformin is Working

While the timeline for experiencing noticeable changes varies from person to person, several key signs indicate Metformin is working as intended. By recognizing these signs, individuals can gain confidence in their treatment and progress toward better health.

NOTE: Not noticing any immediate improvement does not imply the medication is ineffective. The best way to tell if Metformin works is to monitor your blood sugar at home with a glucometer or visit your doctor.

Stable Blood Sugar Levels

One of Metformin therapy's primary goals is to control blood sugar by lowering high blood sugar. Since Metformin helps reduce glucose production in the liver and increases insulin sensitivity, you can expect a gradual decline in blood glucose levels over time.

Regular monitoring of your blood sugar, both fasting and post-meal readings, will help you track your progress. Consistent readings within the target range, particularly after meals when you may be used to higher levels, indicate that Metformin effectively controls your blood sugar.

Improved HbA1c Levels

Another important marker of long-term blood sugar control is the measurement of HbA1c (glycated hemoglobin) levels. This test reflects average blood glucose levels over the past two to three months. With Metformin treatment, you should observe a reduction in your HbA1c levels during routine check-ups. Lower HbA1c values indicate improved glucose management, suggesting that Metformin works effectively.

Weight Loss

Over 85 percent of people with type 2 diabetes are obese or overweight, making excessive weight gain a significant risk factor. Metformin is known to have modest effects on weight loss or weight management, which can benefit individuals with type 2 diabetes. It is important to note that the FDA has NOT approved Metformin to induce weight loss due to inconsistencies. One study from 1995 compared individuals with diabetes who received Metformin treatment and experienced weight loss of up to 3.8kg vs. a non-Metformin receiving group.

A systematic review published in 2005 did not demonstrate significant results with Metformin in weight loss. Of particular note, though, the Diabetes Prevention Program Research group published a study in 2012 that patients adherent to Metformin experienced a 2.1kg average loss over a two year follow up.  One additional study from 2012 associated Metformin with about 5.8kg weight loss in its subjects. While the results are mixed from studies, it can be generalized that Metformin seems to impact weight loss in patients with diabetes positively. Noticing a gradual decrease in weight or better weight control while taking Metformin can be a positive indicator that the medication assists your weight management.

Signs Metformin is not Working

Metformin is generally effective for many individuals; however, there are instances where metformin may not provide the desired results. One study published 2009 found that between 2004-2006, about 42 percent of people prescribed Metformin did not meet treatment goals.

That said, it is essential to understand certain signs indicating Metformin is not working optimally. If you experience any of these signs, don't hesitate to consult your healthcare provider for further evaluation and potential adjustments to your treatment plan:

No Change in Blood Sugar 

If controlling blood glucose levels seems impossible despite taking metformin as prescribed, it could be a sign that the medication is not working. You may notice these persistent spikes after meals or when you wake up (in the morning).

Monitoring your blood sugar at home with a glucometer is the easiest way to track your daily blood sugar levels and identify any patterns of elevated readings

HbA1c has not Improved

HbA1c is a crucial indicator of long-term blood sugar control. If your HbA1c levels remain unchanged or do not show the desired improvement over time (usually after the first three months after starting the treatment), it may indicate that Metformin is not adequately managing your blood sugars. Periodic HbA1c tests, usually performed every three months, can provide insights into the effectiveness of your treatment.

Persistent Hyperglycemia Symptoms

According to the American Diabetes Association, some symptoms of high blood sugar (hyperglycemia) include

  • High levels of glucose in the urine
  • Frequent urination
  • Increased thirst
  • Increased hunger

Since Metformin is intended to improve diabetes-related symptoms, the presence of these symptoms despite regular Metformin usage may suggest that the medication isn't adequately addressing your condition.

It's essential to recognize that occasional increases in blood sugar can occur due to other factors, including stress or consuming a large meal. The best recommendation is to consult your doctor for further evaluation and guidance ONLY when you observe a consistent pattern of high blood sugar levels.

Poor Weight Management

While Metformin isn't officially a weight loss medicine, research has found a strong connection between Metformin usage and significant weight loss in overweight and obese people with type 2 diabetes. However, some individuals may not observe any significant changes regarding weight loss with Metformin.

If you have been taking the medicine as prescribed, following a healthy diet, and engaging in regular physical activity but still struggle with weight gain or find it challenging to lose weight, it could mean that Metformin is not effectively contributing to your weight management.

What Can Metformin Be Used for?

Metformin is widely prescribed as a first-line treatment for type 2 diabetes. It is highly effective in managing blood sugar levels by reducing glucose production in the liver, increasing insulin sensitivity, and facilitating glucose uptake and utilization by peripheral tissues. Metformin helps regulate blood glucose by addressing insulin resistance and can be used as monotherapy or combined with other diabetes medications, including insulin.

Despite being officially used for the management of type 2 diabetes, Metformin can be prescribed off-label for several conditions, including the following:

Type 1 Diabetes

Metformin is not typically prescribed as a primary treatment for type 1 diabetes, which is associated with the pancreas making little or no insulin. However, in some cases where individuals with type 1 diabetes also experience insulin resistance, Metformin may be prescribed to improve insulin sensitivity and manage blood sugar.


Polycystic ovary syndrome (PCOS) is a hormonal disorder affecting 5% to 10% of reproductive-age women. It disrupts menstrual cycles, elevates androgen levels, and impairs regular ovulation, leading to fertility issues.

PCOS is often associated with insulin resistance, making it a risk factor for Type 2 diabetes, as recognized by the American Diabetes Association. Metformin has shown effectiveness in off-label use for PCOS treatment. It addresses metabolic and reproductive abnormalities, improving the chances of conception.


Prediabetes, as defined by the CDC, is a significant health condition where blood sugar levels are abnormally elevated but not yet at the diabetes diagnosis level. Uncontrolled blood sugar can lead to Type 2 diabetes, heart disease, and stroke, emphasizing the importance of addressing prediabetes seriously. Metformin has demonstrated efficacy as an off-label treatment to prevent the progression from prediabetes to Type 2 diabetes.

Weight Management

In a naturalistic outpatient setting, Metformin can trigger weight loss in overweight and obese individuals, regardless of their insulin sensitivity or resistance. This weight loss effect could be linked to the fact that Metformin causes loss of appetite.

Side Effects of Metformin

Metformin can cause some side effects like all medications, but not everyone experiences them. Moreover, where they are present, they are usually mild and resolve within a few weeks. If you notice any of these side effects, please bring them up to your healthcare provider as soon as you realize them. 

Some common side effects that may occur, but are not limited to:

  • Nausea
  • Vomiting
  • Diarrhea
  • Stomach ache
  • Loss of appetite
  • Metallic taste in the mouth
  • Vitamin B12 deficiency (symptoms include extreme tiredness, muscle weakness, sore tongue, mouth ulcers, vision problems, pale or yellow skin, etc.)
  • Low blood sugar (especially when taken with other diabetes medicines, such as insulin or gliclazide). Symptoms include hunger, trembling or shaking, sweating, confusion, and difficulty concentrating.

Frequently Asked Questions

How long does it take for Metformin to work?

Metformin's impact on blood sugar levels is usually not immediate. Typically, noticeable effects can be observed within 48 hours of taking the medication, while the most significant changes may take around 4-5 days to occur. However, it may take some patients several weeks to notice the full benefits of Metformin.

How can I maximize the benefits of Metformin?

To maximize the benefits of Metformin, it is essential to follow a comprehensive approach to diabetes management. This includes maintaining a healthy lifestyle by adopting a balanced diet, engaging in regular physical activity, managing stress levels, getting sufficient sleep, and reducing the intake of certain foods and beverages that may interfere with the medication. Complying with prescribed medication dosage and scheduling regular check-ups with your healthcare provider is also crucial for optimizing the benefits of Metformin.

What are the alternatives to Metformin?

Some commonly prescribed alternatives to Metformin include DPP-4 inhibitors, GLP-1 receptor agonists, SGLT-2 inhibitors, and insulin therapy. The choice of alternative medication depends on individual circumstances and medical history, which you should discuss with your healthcare provider.

Does Metformin give you energy?

Metformin is not prescribed to boost energy levels. Its primary function is to lower blood sugar levels by reducing glucose production in the liver and improving insulin sensitivity. The effects of Metformin on energy levels can vary among individuals, and it is always best to consult your healthcare provider for personalized advice.


Metformin is crucial in managing type 2 diabetes by improving insulin sensitivity and regulating blood sugar levels. Monitoring and recognizing the signs that Metformin is working can help you gauge the effectiveness of your treatment.

Stable blood sugar levels, improved HbA1c levels, weight management, increased energy levels, and a potential reduction in the need for additional diabetes medications are all positive indicators of Metformin's efficacy.

Remember to consult your healthcare provider regularly and discuss any concerns or questions you may have about your treatment plan. With proper monitoring and medical guidance, Metformin can contribute significantly to your overall diabetes management and help you lead a healthier life.


At Diabetic Me, we are committed to delivering information that is precise, accurate, and pertinent. Our articles are supported by verified data from research papers, prestigious organizations, academic institutions, and medical associations to guarantee the integrity and relevance of the information we provide. You can learn more about our process and team on the about us page.

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About the Author

Ely Fornoville

Hi, I'm Ely Fornoville, and I am the founder of Diabetic Me. Being a type 1 diabetic since 1996, I developed a passion to help people learn more about diabetes. I write about diabetes and share stories from other diabetics around the world. I currently use a Medtronic Guardian 4 CGM and a MiniMed 780G insulin pump with Humalog insulin.

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