7 Foods to Avoid While Taking Metformin

Type 2 diabetes is a condition where the body doesn’t use insulin correctly or doesn’t make enough of it. Lifestyle changes and medication — like metformin — can help treat Type 2 diabetes. Along with exercise, metformin helps to keep the blood sugar levels normal before and after meals.

Your diet can have a big effect on your blood sugar levels, but also on how well metformin works. Understanding how some foods affect metformin can guide you in making your food choices and can help promote well-being.

Let’s take a closer look at seven foods (and drinks) you may want to avoid or limit while taking metformin.

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1. Sugary drinks and treats

You’ll want to avoid drinks that are high in natural and added sugar like fruit juice and soda. They won’t stop metformin from working, but they’ll make it harder to keep the blood sugar levels down. Candy, desserts, condiments, and sweet treats tend to be high in sugar. They can also have the same effect and cause blood sugar spikes.

EXPERT PICKS: WHAT TO READ NEXT

• Metformin safety: If you’re taking multiple medications, here are some metformin interactions you should know.

• Diabetes diet plan: When you have diabetes, your diet is important. Review this meal guide for suggestions on what to eat.

• Metformin side effects: Some side effects are common when taking metformin. Learn more about what you can expect while taking this medication.

2. High-sugar fruits

Fruits are generally a healthful food choice, but some have lots of natural sugar. And dried fruit packaged as a snack often has added sugar. Eating these fruits can raise blood sugar levels quickly and interfere with how well metformin works. Examples of fruits high in sugar include:

• Mangoes

• Grapes

• Bananas

• Pineapple

• Watermelon

3. Processed and packaged foods

Processed foods often contain a lot of sugar, salt, and saturated fats. They can make it harder for metformin to lower your blood sugar. If you’ve been trying to lose weight, they can also make it harder for you to reach that goal. Examples of processed foods you should avoid include:

• White bread

• White rice

• Pasta

• Chips

• Sugary cereals

4. High-fat foods

Fatty foods can make it harder for your body to absorb metformin. Eating a lot of fried foods and fatty meats might mean that you’ll need a higher dose of metformin for the same effect. Try avoiding fatty foods and meats like:

• Cheese

• Butter

• Bacon

• Sausages

• Beef ribs

• Pork ribs

5. Dairy products with added sugars

You don’t have to skip dairy completely when taking metformin. But try to avoid sweetened dairy items. These foods add extra calories and sugar, which can make metformin less effective at controlling your blood sugar.

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Examples of sweetened dairy foods you should limit include:

• Flavored yogurts

• Sweetened milk

• Ice cream

6. Big meals with lots of carbs

Eating big meals with lots of simple carbs can overload your body. And, it can leave extra sugar hanging around for your body to process — even if you’re taking metformin. Having smaller, balanced meals can help keep your blood sugar steady.

High-carb foods often include many of the processed foods mentioned above. But in general, try limiting carb-heavy foods and drinks like: 

• French fries

• Cakes

• Cookies

• Soda

• Sweetened tea

7. Alcohol

Drinking alcohol while taking metformin can make your blood sugar drop too low. When you drink alcohol, your liver is busy processing it, so it doesn’t put out as much sugar. This can lead to hypoglycemia (low blood sugar) and its complications. 

Mixing alcohol with metformin can also put you at risk for lactic acidosis. This is a condition where you have too much lactic acid in your bloodstream and it can cause serious illness. 

Before you drink alcohol, be sure to talk with a healthcare professional about how to safely enjoy it while on metformin.

Best foods to eat while on metformin

When taking metformin, eating low-carb and low-fat foods can help you manage your blood sugar. These foods won’t make your blood sugar levels spike as fast, and help to keep them stable. Making more healthful food choices while taking metformin can help the medication work better. Let’s take a look at some healthful options below:

• Lean proteins: Lean proteins, such as chicken, turkey, fish, tofu, and beans, are better choices because they keep your blood sugar from going up too fast. 

• Nonstarchy vegetables: Broccoli, spinach, carrots, and bell peppers are rich in vitamins and minerals and help keep the blood sugar steady. If available, opt for fresh or frozen. If not, low-sodium canned foods are a good alternative.

• Whole grains: Whole grains like oats, quinoa, brown rice, and whole-wheat bread have slow-digesting carbs. This allows your blood sugar to rise more slowly. Just remember not to eat too much of them.

• Low-sugar fruit: Fruits low in sugar, like berries, apples, and citrus fruits, are great choices for a snack. They have less sugar than other fruits and can satisfy your sweet tooth.

• Nuts and seeds: Enjoying a handful of almonds, walnuts, chia seeds, or flaxseeds can be a nutritious way to curb your appetite. They are full of good fats, protein, and fiber, which can help your blood sugar level.

• Plain Greek yogurt and cottage cheese: These dairy products are filled with protein, which helps build strong muscles and keeps you feeling full. Greek yogurt is lower in sugar than flavored yogurts. 

• Healthy fats: Healthy fats, like the ones found in avocados, olive oil, and salmon, help your body use insulin better. This can help to lower the blood sugar.

• Legumes: Legumes are a superfood that can help keep blood sugars in check. Lentils, chickpeas, and black beans are low in sugar, but rich in fiber and protein.  

• Leafy greens: Kale, spinach, and Swiss chard are nutrient-dense leafy greens. They are low in carbs and rich in fiber, which helps to keep your blood sugar levels stable.

• Water: When you take metformin, it’s important to stay hydrated. In some people, it might cause diarrhea, which can make your body lose water faster. 

When you include these healthful and nutritious foods in your meals, it helps you get the most out of taking metformin. Before making changes, remember to talk with a healthcare professional about what foods are best for you and your health goals.

What should you do if you eat food you shouldn’t while taking metformin?

Following a strict diet isn’t easy. And occasionally, you might eat food you shouldn’t while taking metformin. Here’s what you should do if that happens:

• Monitor your blood sugar levels for a few hours to see how your body reacts to the food you’ve eaten.

• Take a short walk to lower blood sugar levels and improve insulin sensitivity.

• Drinking water can help flush out extra sugar from the body. It also prevents dehydration.

These tips can help you handle minor slip-ups with your diet. But be sure to contact your diabetes care team if you notice unusual symptoms after eating, such as:

• Extreme thirst

• Frequent urination

• Nausea and vomiting

• Weakness

• Confusion

• Prolonged blood sugar levels greater than 250 mg/dl

What other metformin interactions should you watch for?

In addition to avoiding certain foods, there are other interactions to consider when taking metformin. 

Medications

Some medications can interact with metformin. They can affect its effectiveness and increase the risk of side effects. These include certain:

• Antibiotics

• Blood pressure medications

• Cholesterol medications

• Diabetes medications

• Steroids

• Seizure medications

Always talk with your diabetes care team about all the medications you’re taking. This includes over-the-counter medications and supplements.

Kidney health

After being processed in the body, metformin is then mainly removed by the kidneys. If your kidneys don't work well, metformin can build up in the body and raise your risk of side effects. A healthcare professional will track your kidney function regularly while you’re taking metformin.

Contrast

Some imaging studies, like CT scans or MRIs, may require you to receive contrast. This can help give your care team better images in some cases, but it can lead to kidney failure in people at high risk. To reduce the risk of kidney damage, you may need to stop taking metformin for a short time after having a test with contrast.

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Written by:

Bernadette Anderson, MD, MPH

A native of Saginaw, Michigan, Dr. Bernadette earned an undergraduate degree in psychology from the University of Michigan, Ann Arbor. She completed a master's degree in public health at the University of California, Berkeley, and a doctorate of medicine from the Medical College of Ohio.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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