Metformin: A Guide

When it comes to treating type 2 diabetes, there is no medicine more widely used than Metformin.

Metformin (Glucophage) is on the World Health Organization’s list of essential medicines due to its excellent effectiveness and safety profile.

Metformin is also very inexpensive. For these reasons, diabetes organizations recommend using Metformin as first-line therapy for type 2 diabetes (diabetes mellitus).

But what exactly is Metformin, and what are the benefits and drawbacks to its use? This article will provide a comprehensive overview of the popular drug.

What is Metformin?

Metformin is a medicine taken in pill form that is derived from the French lilac plant (Galega officinalis).

Metformin was first used to treat diabetes in the 1920s. But due to concerns about metformin side effects and being overshadowed by insulin, it did not become a significant treatment until the late 1990s and early 2000s.

Metformin was initially marketed under the name Glucophage xr (which means glucose-eater) and is now available in generic form.

The general starting dose of Metformin is 500mg per day, and this can be increased up to 2000mg per day. Metformin is taken once or twice daily and also includes a long-acting form known as Metformin ER (extended-release).

RELATED: Metformin Recall: Is Your Medication Affected?

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Who should consider taking Metformin?

Type 2 diabetes is a condition that can often go undetected for many years before it is formally diagnosed. In type 2 diabetes, the body slowly becomes less effective in using its insulin. This is insulin resistance. People with insulin resistance may benefit from taking metformin since it can increase insulin sensitivity.

Symptoms of insulin resistance

  • Extreme thirst or hunger.

  • Feeling hungry even after a meal.

  • Increased or frequent urination.

  • Tingling sensations in hands or feet.

  • Feeling more tired than usual.

  • Frequent infections.

Insulin is a hormone the pancreas produces that helps regulate blood glucose (blood sugar) levels by ferrying glucose out of the blood and into cells where the body can use it for energy.

If insulin is not working correctly, or there is not enough insulin (insulin deficiency), then the glucose stays in the bloodstream. This leads to high blood glucose levels.

You can test for high blood glucose levels at a doctor’s office to confirm the diagnosis of diabetes.

Diabetes is formally diagnosed with fasting blood glucose greater than or equal to 126 mg/dl (7 mmol/L) or an A1c level of 6.5% or higher.

Essentially it happens like this: when you eat foods containing sugars or starches, they break down into blood glucose. This stimulates the pancreas to release insulin to bring the blood glucose level down.

Type 2 diabetes disrupts this system because the body becomes more resistant to its own insulin.

High blood glucose can then damage many organ systems, including eyes, kidneys, heart, and blood vessels.

This insulin resistance can happen slowly over many years before blood glucose levels are detected to be too high. This is because the body will overcompensate by releasing more insulin. Over time, this can burn out the pancreas and lead to an insulin deficiency.

High insulin levels are often associated with central obesity, cholesterol abnormalities, and/or high blood pressure (hypertension). When these disease processes occur together, it is metabolic syndrome.

Thus, the goal of any diabetes treatment is to control blood glucose. Medicines such as insulin do this by correcting insulin deficiency, and other medicines like metformin work to decrease insulin resistance.

Why doctors might recommend metformin

Many doctors and diabetes specialists recommend Metformin as the first medicine to treat type 2 diabetic patients because:

  • It helps to decrease insulin resistance.

  • It improves blood glucose.

  • Delays the progression of the disease.

  • Most people tolerate it well.

However, people diagnosed with diabetes should be given a choice in their treatment, and some people prefer to try lifestyle changes or other non-medicine approaches before starting Metformin.

In less common cases, there are specific medical reasons why someone should not take Metformin.

Research suggests that lifestyle changes, especially modest weight loss and exercise, can be equally or more effective than Metformin alone.

Metformin is also sometimes used to prevent type 2 diabetes in the first place. Blood sugar levels that are higher than normal, but not high enough to be classified as diabetes, are known as prediabetes.

Prediabetes is not a disease itself, but rather a risk factor for developing type 2 diabetes.

Lifestyle changes are the primary treatment strategy for preventing diabetes. Metformin can add to lifestyle therapy or be used when lifestyle changes alone are not enough to prevent type 2 diabetes.

metformin diet

RELATED: Metformin Diet: 5 Foods To Eat and 6 You Should Avoid.

How does Metformin work?

Metformin works in the body with three main actions:

  • Improves insulin sensitivity.

  • Decreases glucose production by the liver.

  • Decreases absorption of glucose from food

Since type 2 diabetes is a disease of insulin resistance, helping the body to use its own insulin is an essential target for diabetes therapy.

Metformin improves insulin sensitivity by targeting various body tissues and organ systems to increase the usage of glucose.

This means that instead of blood glucose staying in the bloodstream, the glucose will more readily be taken up by the body through the action of insulin. This restored sensitivity to insulin is vital in preventing the progression of diabetes.

Another major action of Metformin is to reduce glucose production by the liver.

The liver is responsible for many tasks, which include the regulation of blood glucose. If glucose levels fall too low, the liver then creates its own glucose and sends it into the bloodstream. This is gluconeogenesis.

In those with type 2 diabetes, gluconeogenesis happens more often than usual, which can be problematic as this extra blood glucose is challenging to get rid of.

Metformin helps in this regard by reducing gluconeogenesis.

Finally, studies show Metformin can reduce the absorption of glucose in the first place.

When the body breaks down sugars or starches (carbohydrates) to glucose, the glucose enters the gastrointestinal tract where is then absorbed into the bloodstream. If less glucose is absorbed, blood glucose will be lowered.

Scientists are still learning exactly how Metformin works, but in general, Metformin improves the underlying issues that result in high blood glucose (blood sugar levels).

Who Should Not Take Metformin?

Metformin is used as a first-line treatment for type 2 diabetes, but it is not appropriate for everyone. The following are situations when people should not use Metformin:

  • Metabolic acidosis.

In these cases, Metformin either would not be effective or will increase the risk of dangerous complications. In that case, doctors may suggest alternative diabetes drugs to metformin.

Complications and Side Effects of Metformin

With any medication therapy, there are adverse effects, risks, and precautions, and Metformin is no exception.

While generally safe and well-tolerated, the decision to start Metformin should be considered carefully with a qualified medical professional.

Below are some complications and side effects of metformin.

Lactic acidosis

Lactic acidosis is a rare complication that is serious and potentially fatal. This occurs when levels of lactate in the body rise to unsafe levels and acidify the body.

This complication can often be prevented with appropriate monitoring of renal function and caution with use in older populations. It is worth repeating that this complication is exceptionally uncommon.

Gastrointestinal Issues

Many people taking metformin report stomach or intestinal discomfort, abdominal pain, and diarrhea. For some, it is severe enough to stop taking Metformin. These issues are more common when first taking Metformin and may subside with time or by trying a lower dose. There is also an extended-release form of Metformin that can decrease gastrointestinal issues.

RELATED: What Happens When You Stop Taking Metformin for Diabetes?

Vitamin B12 deficiency

Uncommonly, Metformin can cause low vitamin B12 levels. Thus, vitamin B12 is usually monitored with long-term metformin therapy. You can also correct this with a vitamin b12 supplement.

metformin side effects

Benefits of Metformin Therapy

There is a reason Metformin is one of the most widely used medications to treat diabetes. The following are some benefits of Metformin.

No risk of low blood sugar

Low blood sugar, or hypoglycemia, is a severe complication of insulin and other diabetes medications. However, Metformin alone does not cause hypoglycemia. This is because Metformin does not increase insulin production; it only helps the body process glucose that is already present.

Safety profile

The side effects of Metformin are relatively minor for most people, and serious complications are infrequent.


Metformin is available as a generic medication and is very inexpensive.

Weight loss

Metformin can cause weight loss, which is helpful in managing type 2 diabetes.

How Effective is Metformin?

Many randomized controlled clinical trials have tested the effects of metformin.

In these controlled studies, researchers found that Metformin could decrease fasting glucose by about 60mg/dl, after-meal glucose by 80 mg/dl, and reduce hemoglobin A1c by 1.8%. These results are significant because they can be the difference between uncontrolled and controlled blood glucose.

To review, a target fasting blood glucose for someone with type 2 diabetes is 80-130 mg/dl. A target after-meal glucose is less than 180 mg/dl and a target A1c is less than 7%.

In addition to blood glucose improvements, Metformin can also lower cholesterol and prevent cardiovascular disease, which is the most common cause of death in those with type 2 diabetes.

Metformin has been used in the management of metabolic and reproductive abnormalities associated with polycystic ovary syndrome.

However, adequate and well-controlled clinical trials evaluating metformin therapy for women with PCOS remain limited, particularly regarding long-term effects.

Type 2 diabetes is a risk factor for Alzheimer’s disease, and insulin sensitivity may be altered in Alzheimer’s patients. Some studies suggest metformin may reduce Alzheimer’s risk, but others have found long-term use may increase it.

glyco optimizer

Natural Treatments for Diabetes

Despite the benefits of metformin therapy, many people are reluctant to start medications and are seeking other approaches to manage their diabetes.

The good news is that there are several lifestyle changes that can help to improve glycemic control and reduce or even eliminate the need for medications.

Starting lifestyle changes early in the course of type 2 diabetes can improve the chances of achieving diabetes remission, which is a state of normal blood glucose without the use of medications.

Weight loss

Research is clear that having extra weight is closely tied to insulin resistance. Losing even modest amounts of weight will improve blood glucose. In fact, some research has found that losing just 10% of body weight can result in a remission of type 2 diabetes in those newly diagnosed.

Losing weight is difficult for most people, but there are several strategies that can help:

Make it a lifestyle change

Diets do not work because they involve making temporary adjusts to your food habits or following lists of “good” foods and “bad” foods.

The issue with this approach is that eventually, people will return to their normal eating habits because they did not make any underlying lifestyle change. Instead, focus on small, realistic, and sustainable goals that you can continue for long-term treatment.

Manage hunger

Being too hungry will make it hard to stick with any goals, so the key is to prevent this from happening in the first place. Avoid skipping meals. Keep healthy snacks on hand if meals will be very far apart.

Be smart when grocery shopping

Plan meals, stick to a grocery list, and avoid buying foods that will be tempting all week such as pastries, candies, and other junk foods.

Keep a food diary

Paying more attention to eating habits is a great way to turn off the eating “auto-pilot” and make smart food choices.

A food diary can be a simple pen and paper or by using one of the many available apps for mobile phones. The phone apps have the added benefit of automatically calculating calories.

Cook more at home

Eating foods outside the home will almost always result in a higher-calorie meal. Cooking just a few more meals per week will not only result in fewer calories but will be healthier too.

Eating at home does not have to involve complicated or time-consuming recipes. For example, a tuna sandwich with an apple and carrots dipped in hummus is miles better than most fast food offerings.

Avoid liquid calories

Soda, juice, sports drinks, sugary coffee, and alcohol can be the difference between weight gain and weight loss. Liquid calories do not contribute much to feelings of fullness, which is why they are easier to overdo. Instead, plain water or other sugar-free options are advised.

Limit carbohydrates

Carbohydrates, or carbs, are one of the three main nutrients in food (known as macronutrients).

Carbs directly break down into glucose when digested and cause a rise in blood glucose after meals. Thus, limiting carbs is an important strategy to manage blood glucose. There are several methods to control carbohydrate intake.

Plate method

The plate method is a simple strategy to control portion sizes of carbs. To follow the plate method, imagine a regular-sized plate.

Half of this plate should include non-starchy vegetables, such as greens, tomatoes, carrots, etc. One-quarter of the plate should consist of lean proteins such as chicken, turkey, fish, eggs, or tofu.

Finally, the last quarter of the plate can include starches such as bread, rice, corn, beans, and potatoes. The plate method also provides room for one serving of fruit, such as an apple or a cup of berries. This way, you can still enjoy carb-containing foods, but they will automatically be in the correct portions.

Carbohydrate counting

Many people with diabetes become familiar with the carb counting method, which involves understanding exactly how many carbohydrates are in the foods they eat and sticking to specific targets.

For example, a carb target could be 45 grams per meal. A slice of bread is about 15 grams of carb, and an apple is another 15 grams. Thus, a turkey sandwich with an apple would be right at about 45 grams of carb.

There are several books and phone apps that can make carb counting easier. There is no ideal number of carbs for everyone, and this number is often individualized based on a person’s blood glucose response.

Very low carbohydrate eating

Very low-carb eating patterns generally consist of 15-30 grams of carbs for the entire day, with fat and protein making up the rest. The popular ketogenic diet is an example of a deficient carb diet, which results in diabetic ketoacidosis.

When you limit carbs to this degree, it can be easier to keep blood glucose within normal limits, even resulting in diabetes remission in some cases.

These diets are not for everyone; however, as they require strict adherence, and many foods are simply not allowed. In addition, although there is some research supporting the benefits of very low-carb diets in diabetes, there is limited long-term research.

Getting enough physical activity

Exercise is a tried and true method to combat insulin resistance.

When engaging in physical activity, the body is better able to “soak” up the glucose from the blood. Exercise can also lower blood pressure, cholesterol, and reduce the inflammation associated with diabetes.

The benefits of exercise go far beyond helping with long-term weight loss and are considered a form of medicine in itself.

The guidelines state that at least 150 minutes of physical activity is recommended per day, but any amount of exercise is beneficial.

However, despite these benefits, today’s modern world can make it difficult to get enough exercise. It is important to remember that exercise does not have to include a boring treadmill or even a gym membership. Here are some tips to increase exercise.

Wear a pedometer

Keeping track of steps can provide instant feedback on the amount of activity you did in a day. To track steps, first, wear a pedometer for 1 week without making any changes. Then, take the average number of steps for that week and increase by 500 each day. Continue increasing by 500 each week until you reach a goal of 10-15,000 steps.

Find ways to sneak in exercise

No time for the gym? No problem! Walk the dog, do a lap around the house, get up every hour at work, take the stairs instead of the elevator, park further away. It all adds up!

Weather-proof your exercise

Living in a climate with seasonal winters can make it challenging to exercise year-round. Make sure to “weather-proof” your exercise plan by joining a health club, doing home exercises, or walking at a local shopping center.

Include strength training

At least 2 days per week, include exercises that work the muscles such as push-ups, squats, or dumbbell curls. Although a gym can provide access to lots of exercise equipment, there are a variety of household objects you can use as well. Items such as exercise bands, a dumbbell set, a door pull-up bar, and more can bring strength training in the comfort of the home.


Certain supplements have been studied for their role in helping to treat type 2 diabetes. These supplements include cinnamon, alpha-lipoic acid, berberine, psyllium, and white mulberry extract.

Research on the effectiveness of these supplements varies, but some research has supported modest glucose-lowering effects from their use. Many people prefer to take supplements because they generally have fewer side effects and are more natural.

It is important to remember that you should use any supplement in conjunction with lifestyle changes and, if needed, medication therapy.


Metformin is a medication to treat type 2 diabetes. It is often the first medicine that is used because it is highly effective with few side effects. It works by improving insulin resistance, reducing the output of glucose from the liver, and reducing glucose absorption from food.

Some people should not take Metformin, and a common side effect is gastrointestinal discomfort. Serious risks of Metformin are rare.

You can also manage type 2 diabetes with lifestyle changes including changes to diet and exercise. In some cases, lifestyle changes alone are enough to manage type 2 diabetes without medications.

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  1. Bailey, C. J. (2017, September). Metformin: historical overview. Retrieved from
  2. Drug Approval Package. (n.d.). Retrieved from
  3. Prediabetes – Your Chance to Prevent Type 2 Diabetes | CDC. (n.d.). Retrieved from
  4. Professional Practice Committee: Standards of Medical Care in Diabetes—2019

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