How does bitter melon affect blood sugar levels?

Various treatments can help people keep their blood sugar levels within the target range, including healthful lifestyle adjustments. A person may also use complementary therapies and supplements, such as bitter melon.

This article looks at the use of bitter melon for diabetes, whether it is a healthful complement to treatment, and how it may impact blood sugar levels. It also looks at some ways of using bitter melon, including preparation and recipe tips.

What is bitter melon?

For centuries, people throughout the world have used bitter melon — also called bitter gourd, karela, and balsam pear — in food and as medicine.

Rich in vitamins and minerals, bitter melon grows on the vine of the Momordica charantia plant. It is the most bitter of all fruits and vegetables.

Studies into the safety and effectiveness of bitter melon as a medical treatment are limited.

People have used it as an antibacterial agent, an antioxidant, and an immune system modulator. They have also used bitter melon to help treat or prevent:

• diabetes
• inflammation
• constipation
• ulcers
• respiratory diseases
• malaria
• cancer

Studies have supported some of these uses for bitter melon. A review published in 2015 concluded that the melon contains compounds that may help control blood glucose (sugar) and lower levels of blood lipids (fats).

As a result, it may benefit people with:

• diabetes
• obesity
• cardiovascular conditions

These often occur together, and they all characterize a condition called metabolic syndrome.

A study published in 2010 concluded that bitter melon extract can hinder the growth of breast cancer cells.

Effects on diabetes

A number of clinical studies have investigated the effect of bitter melon on diabetes to see whether it could help keep blood glucose levels within a safe range.

Blood sugar levels

Some researchers believe that bitter melon contains substances that suppress the appetite and decrease blood sugar levels. In this way, it behaves similarly to insulin.

One study, published in the Journal of Ethnopharmacology in 2011, looked at people with type 2 diabetes who consumed up to 2,000 milligrams of bitter melon per day.

The researchers concluded that bitter melon had a “modest hypoglycemic effect.” The impact was smaller than that experienced by people who took 1,000 milligrams per day of metformin, a drug commonly used to reduce blood sugar levels.

In 2018, researchers found that compounds in bitter melon might help reduce blood glucose levels. When they fed rats a diet that included bitter melon leaf, they noted changes in receptors that could improve blood sugar levels. The bitter melon leaf made up 5–20% of the rats’ diets.

Effect on hemoglobin A1C levels

A study published in 2007 compared the effects of a placebo with those of bitter melon supplements. Among the 40 participants, one group took two capsules of the supplement three times a day for 3 months.

The aim was to see whether the bitter melon would cause a drop in participants’ A1C levels. These are average blood sugar levels over a 2–3-month period.

The researchers noticed a small decrease in A1C levels, of less than 0.25%. The placebo group, meanwhile, showed no change.

Though the size of the study and the drop in A1C levels were small, the authors hope that they will encourage larger studies.

A 2014 review from Nutrition & Diabetes looked at four studies that compared the effects of bitter melon supplements with those of no diabetes treatment at all.

The authors found no evidence that bitter melon had any significant effects on A1C levels or fasting plasma glucose levels.

They determined that most results were inconclusive, but that larger studies might help determine bitter melon’s effectiveness as a supplemental treatment for diabetes.

Here, learn more about A1C tests and what the results mean.

Further research

In 2016, authors of a review analyzed several studies relating to bitter melon, including its effects on diabetes.

The authors concluded that bitter melon may have properties that can help lower blood glucose but noted that further research was necessary to establish how effective it could be and how exactly it works.

Could other foods help reduce blood sugar? Find out more.

As a therapy

People can eat any part of the fruit, or take it as:

• a powder
• a supplement
• a juice

Most Asian grocery stores sell bitter melons. Powders, supplements, and juices are available for purchase at health food stores and online.

How much to consume

Anyone considering taking bitter melon alongside their diabetes treatment should consume no more than:

• 50–100 milliliters daily of juice
• about 2–3 ounces throughout the day
• one small bitter melon per day
• the amount of supplement a doctor advises

A person should take a supplement after:

• talking to their doctor about whether to use it and the right dosage
• checking the instructions on the packaging

Some supplements may counter or increase the effects of existing medications.

What other herbs and supplements could help people with type 2 diabetes? Learn more here.

Bitter melon in the diet

Bitter melon grows in parts of Asia, South America, the Caribbean, and Africa, where it is a popular ingredient in a variety of dishes.

For people with type 2 diabetes, a diet rich in fresh fruits and vegetables is part of treatment, and it may help reverse the progression of prediabetes.

People with either type 1 or type 2 diabetes have a higher risk of cardiovascular disease and other complications. A healthful diet that includes foods rich in antioxidants can help prevent many health problems.

Nutrients

Apart from its possible antioxidant and antidiabetic properties, bitter melon contains other important nutrients.

These include:

• protein
• carbohydrates
• calcium
• phosphorus
• magnesium
• potassium
• zinc
• vitamins C, A, and B

All of these provide health benefits.

Recipe tips

Ways of preparing bitter melon include:

• adding it to soups and stews
• incorporating it into stir-fry dishes
• using it in curries
• serving it fried in batter
• eating it stuffed with rice or other ingredients
• enjoying it in an omelet
• including it in bean dishes

Learn more here about how beans can benefit a person with diabetes.

Reducing the bitterness

All of the plant is edible, but some people find it too bitter. To reduce the bitterness, try:

• scraping the rough surface
• removing the seeds
• soaking it in yogurt for 1 hour before use
• cooking it with vegetables such as potatoes or onions to dilute the taste

Some recipes suggest adding sugar or salt while cooking, but people with diabetes need to carefully account for these additions.

Sugar can increase blood glucose levels, and salt can lead to high blood pressure and put a person at risk of cardiovascular disease, two complications of diabetes.

Here, find out more about foods that people with diabetes should eat or avoid.

Risks

If a person consumes too much bitter melon, either as a food or a supplement, they may experience:

• gastrointestinal problems, including diarrhea
• vomiting and diarrhea, in children
• low blood sugar, especially if they are already using medications for diabetes

Pregnant women should not consume bitter melon in any form because it may increase the risk of bleeding, contractions, and pregnancy loss.

Bitter melon, the fruit or a supplement, could be a safe and affordable way to lower blood sugar levels in people with diabetes, but determining this will require more research.

Anyone thinking of increasing their intake of bitter melon in any way should speak to their doctor first and follow the instructions on any packaging. Also, make sure that supplements come from a reputable source, such as one with a USP verification mark.

Closely monitor blood glucose levels, in case the bitter melon is interacting with diabetes medications and reducing blood sugar to dangerously low levels.

Conclusion

Some compounds in bitter melon show promise for treating or preventing a number of health conditions, including diabetes.

However, identifying exactly how and why it might be useful and how safe bitter melon is in the long term will require further research.

In time, bitter melon or its compounds could provide a complementary treatment for diabetes and high blood sugar.