Answer:

Many different supplements may help lower or control blood sugar in people with prediabetes or type 2 diabetes who experience hyperglycemia (when blood glucose rises higher than normal). These supplements are discussed below. More details about each, including dosage, drug interactions, potential side effects, and ConsumerLab.com's reviews of products on the market, can be found by clicking on the links.

Due to the seriousness of hyperglycemia, it is important to consult with your physician regarding use of these supplements.

Cinnamon supplements may modestly improve blood sugar in people with type 2 diabetes whose blood sugar is not well controlled with medication. In addition, one small study found that a branded cinnamon extract reduced fasting blood sugar by an average of about 10 mg/dL in prediabetic men and women with metabolic syndrome. Keep in mind, however, that only certain varieties of cinnamon have been shown to have this effect, and long-term safety studies have not been conducted.

Increased intake of magnesium from the diet and supplements has generally been associated with a decrease in the risk of developing type 2 diabetes — particularly among people with low intakes. Magnesium supplementation has been shown to insulin sensitivity in people with type 2 diabetes, and may lower blood sugar levels in people with prediabetes or metabolic syndrome.

Curcumin (from turmeric) may improve blood sugar levels, according to preliminary studies, and one study found curcumin to dramatically lower the chances of prediabetes in middle-aged, slightly overweight men and women with somewhat higher than normal blood sugar levels.

Alpha lipoic acid may improve insulin sensitivity and blood sugar control in people with type 2 diabetes, although it may only slightly reduce levels of glycosylated hemoglobin (HbA1c).

Chromium picolinate may help some people with type 2 diabetes decrease fasting blood glucose levels as well as levels of insulin and glycosylated hemoglobin (HbA1c). However, be aware that high doses may worsen insulin sensitivity in healthy people who are not obese or diabetic.

Several small, preliminary studies suggest that apple cider vinegar, taken as a liquid, may reduce the rise in blood sugar that occurs after eating, although it's not clear if it is beneficial to people with type 2 diabetes. Apple cider vinegar tablets and pills do not appear to have the same effect on blood sugar.

Having adequate blood levels of vitamin D may reduce the risk of insulin resistance in people who are obese. There is some evidence that a certain blood level of vitamin D is needed for normal glucose metabolism in women who are overweight and obese (but not diabetic), but it is not clear whether any further benefit is gained with higher blood levels.

In healthy people, consuming a moderate amount of extra virgin olive oil with a meal has been shown to reduce increases in blood sugar after the meal compared to the same meal consumed with corn oil. In people with type 1 or type 2 diabetes, olive oil may improve glucose metabolism.

Increasing dietary fiber, especially insoluble fiber from cereal and grains, is associated with a reduced risk of diabetes and has been shown to reduce fasting blood glucose and modestly lower HbA1c in people with type 2 diabetes (Martin, J Nutr 2008; Post,J Am Board Fam Med 2012). In people with type 1 diabetes, 50 grams of dietary fiber per day has been shown to significantly improve blood sugar control and reduce hypoglycemic events (Giacco, Diabetes Care 2000). The American Dietetic Association states that "diets providing 30 to 50 g fiber per day from whole food sources consistently produce lower serum glucose levels compared to a low-fiber diet. Fiber supplements providing doses of 10 to 29 g/day may have some benefit in terms of glycemic control." (Slavin, J Am Diet Assoc 2008). Although ConsumerLab.com has not tested fiber products, we have produced a webinar about that provides more information.

Ginseng, both American and Korean Red ginseng (from Panax ginseng), may reduce blood sugar levels in people with diabetes, according to preliminary research.

Drinking whey protein before a high glycemic meal may help to lessen increases in blood sugar after the meal in people with well-controlled type 2 diabetes.

Silymarin, a component of milk thistle, may decrease blood sugar and hemoglobin A1c in people with type 2 diabetes, and reduce insulin resistance in people with coexisting diabetes and alcoholic cirrhosis.

Inulin, a type of prebiotic, may improve measures of blood sugar control in women with type 2 diabetes, although it did not improve blood sugar levels or insulin resistance in a study of prediabetic men and women.

Berberine (a compound found in plants such as barberry, Oregon grape and goldenseal) may reduce blood sugar levels in people with metabolic syndrome or type 2 diabetes, according to a few small studies.

Fenugreek may help to lower blood sugar, according to preliminary studies, and one study found fenugreek extract to significantly improve some measures of blood sugar control and insulin response in people with type 2 diabetes.

D-ribose, often promoted for energy or sports performance, may also lower blood sugar levels (Fenstad, Internet J Nutr Wellness 2007).

Gymnema sylvestre may decrease average blood sugar levels in people with type 1 or type 2 diabetes, according to two small, preliminary studies using 400 mg of a standardized extract (GS4 from Sabinsa, standardized to 25% gymnemic acid) for six months or more (Baskaran, J Ethnopharmacol 1990; Shanmugasundaram, J Ethnopharmacol 1990).

White mulberry (Morus alba or Morus indica) has been traditionally used in Asia to help treat type 2 diabetes, and there is some preliminary evidence to support this use. Mulberry leaf extract (species not given) may lessen increases in blood sugar after ingestion of table sugar in healthy people and people with type 2 diabetes (Mudra, Diabetes Care 2007). Among people with type 2 diabetes, taking 1 gram of powdered white mulberry leaf three times daily (after breakfast, lunch and dinner) for four weeks was found to lower fasting blood sugar by 27%, while taking 5 mg of the anti-diabetes drug glibenclamide lowered fasting blood sugar by only 8% (Andallu, Clin Chim Acta 2001).

There is mixed evidence as to whether CoQ10 may lower blood sugar. To be safe, people with diabetes or who take medication to lower blood sugar should consult a physician before using.

Amla (Emblica officinalis), also known as Indian gooseberry, has been traditionally used in Ayurvedic medicine for type 2 diabetes, and some preliminary evidence supports this use. One small study in Pakistan that included 32 people has shown that taking 1, 2, or 3 grams of powdered amla fruit once daily with breakfast can lower both pre- and post-meal blood sugar levels in people with or without diabetes after about 2-3 weeks of use (Akhtar, Int J Food Sci Nutr 2011). However, more research is needed to determine which form and dosage of amla has greatest benefit, whether the short-term effects persist long-term, and whether amla has benefit when taken with prescribed medicines for diabetes.

Preliminary evidence suggests certain other supplements, including aloe, ashwagandha, ginkgo, green coffee bean extract, glucosamine, black cohosh, rhodiola, reishi mushroom and tart cherry juice may lower blood sugar. While there is not enough clinical research to support the use of these supplements for this purpose, it's important to keep this in mind, as they could enhance the blood sugar lowering effect of other supplements or medications you may be taking.

There are a few supplements which may worsen blood sugar control or insulin sensitivity in certain people: excessive amounts of niacin may elevate blood sugar levels, and prescription digestive enzymes may cause an increase or decrease in blood sugar levels in people with exocrine pancreatic insufficiency. CLA (conjugated linoleic acid), a popular supplement for slimming, may worsen blood sugar control in diabetics and in obese people without diabetes.

Although fish oil does not appear to adversely affect blood sugar levels in people with diabetes, one study reported that a large daily dose of krill oil (providing a modest amount of EPA and DHA) reduced insulin sensitivity in overweight, middle-aged men by about 27% -- which could potentially increase the risk of diabetes.

Vitamin C may lower blood sugar levels after eating in people with type 2 diabetes, but be aware that high doses may interfere with certain blood sugar tests.

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9 Comments

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YUVAL8593
April 2, 2016

HI
WHAT DO YOU KNOW ABOUT GYMNEMA SYLVESTRE FOR THAT SAME PURPOSE?
YUVAL

ConsumerLab.com
April 17, 2016

Hi Yuval - We've now added information about Gymnema sylvestre to the answer above.

Joann8576
March 30, 2016

I am surprised you did not mention Fenugreek as lowering blood sugar in diabetics. My Doctor has me taking it and it has helped to keep my HbAic in a good control range.

ConsumerLab.com
March 31, 2016

Hi Joann- Thank you for sharing your experience taking fenugreek. We've now added information about this to the answer above.

Judith8575
March 30, 2016

I notice that white mulberry leaf extract is one of the principal ingredients in Dr. Joel Fuhrman's proprietary blend of his Glucose Biotect. Is there a report or studies on white mulberry? This product is quite effective.

ConsumerLab.com
April 18, 2016

Thank you for your question, Judith. We've now added information about white mulberry to the answer above.

Arthur8574
March 30, 2016

I have used organic psyllium husk fiber (2 tbsp 30 minutes before meals) extensively with my family practice patients (and myself) with excellent results. I use Now brand because it does not have sugar or artificial sweeteners like Metamucil - and it is much cheaper. I have no financial ties to Now Foods - www.nowfoods.com/.

One of many research articles on Pubmed:

Nutr Rev. 2009 Apr;67(4):188-205. doi: 10.1111/j.1753-4887.2009.00189.x.
Health benefits of dietary fiber.
Anderson JW1, Baird P, Davis RH Jr, Ferreri S, Knudtson M, Koraym A, Waters V, Williams CL.
Abstract
Dietary fiber intake provides many health benefits. However, average fiber intakes for US children and adults are less than half of the recommended levels. Individuals with high intakes of dietary fiber appear to be at significantly lower risk for developing coronary heart disease, stroke, hypertension, diabetes, obesity, and certain gastrointestinal diseases. Increasing fiber intake lowers blood pressure and serum cholesterol levels. Increased intake of soluble fiber improves glycemia and insulin sensitivity in non-diabetic and diabetic individuals. Fiber supplementation in obese individuals significantly enhances weight loss. Increased fiber intake benefits a number of gastrointestinal disorders including the following: gastroesophageal reflux disease, duodenal ulcer, diverticulitis, constipation, and hemorrhoids. Prebiotic fibers appear to enhance immune function. Dietary fiber intake provides similar benefits for children as for adults. The recommended dietary fiber intakes for children and adults are 14 g/1000 kcal. More effective communication and consumer education is required to enhance fiber consumption from foods or supplements.

ConsumerLab.com
March 31, 2016

Hi Arthur - Thank you for sharing your experience taking fiber. We've added information to the answer above, including a link to our webinar about fiber supplements ( https://www.consumerlab.com/fiber_supplements_webinar_2012.asp), which may be of interest to you.

Diane 11403
November 16, 2016

Hi Arthur, My husband is prediabetic and does take Metamucil so I'm interested in your Now product. I looked online and found they have a couple but can't tell the difference, one says psyllium husk powder and the other whole psyllium husks, which do you use?

Thanks,
Diane

Deborah20578
August 13, 2020

What about Amla?

ConsumerLab.com
August 18, 2020

Hi Deborah - We've now added information about amla to the answer above.

John18620
November 11, 2019

My Glucose was in the low 120"s and my A1c was 6+ After taking Berberine 3x a day for 4 months my Glucose is 89 and a1c is 5.4. It has stayed that way even though I was prediabetic for over 5 years.

Linda19099
February 17, 2020

Could you share the brand of berberine that you used please, John?

Roberta16241
November 26, 2017

My blood sugar is in the pre-diabetic range. D-ribose raises my blood sugar quite a bit. Test and see what it does for you before committing to taking it. Start testing your blood sugar 1/2 hour after taking the D-ribose and every 1/2 hour for about 2 hours to fully test the effects. If you take it in a liquid on an empty stomach, it can get into your bloodstream pretty fast.

Pam11664
February 9, 2017

I started taking Prickly Pear supplements and eating the chopped pear paddles from the mexican supermarket and my H1c dropped from 6.1 to 5.8 in 3 months. It seemed to be more effective than the Cinsulin that I had previously taken. I triy to do some exercise each day which I believe also helps.

ConsumerLab.com
February 9, 2017

Hi Pam - Thank you for sharing your experience with both of these supplements. There is some preliminary evidence for prickly pear, although there do no appear to be double-blind, placebo-controlled trials. See the Encyclopedia article for more information: https://www.consumerlab.com/tnp.asp?chunkiid=21820.

You can also get more information about CinSulin and other cinnamon formulas, and our test of products, in our Cinnamon Supplements Review: https://www.consumerlab.com/reviews/_/cinnamon/

kevin 11575
January 8, 2017

For a good view how the body works with fat, insulin, cortisol,... etc. read the book of Mike Mutzel 'Belly Fat Effect'. You get very good understanding trough science how it al works together.

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