Scientists are testing many different supplements to determine if they help lower blood sugar.
Such supplements could benefit people with prediabetes or diabetes — particularly type 2.
Over time, taking a supplement alongside diabetes medication may enable your doctor to decrease your medication dose — though supplements likely can’t replace medication entirely.
Here are 10 supplements that may help lower blood sugar.
When people with prediabetes — meaning a fasting blood sugar of 100–125 mg/dl — took 250 mg of cinnamon extract before breakfast and dinner for three months, they experienced an 8.4% decrease in fasting blood sugar compared to those on a placebo (3).
In another three-month study, people with type 2 diabetes who took either 120 or 360 mg of cinnamon extract before breakfast saw an 11% or 14% decrease in fasting blood sugar, respectively, compared to those on a placebo (2).
Additionally, their hemoglobin A1C — a three-month average of blood sugar levels — decreased by 0.67% or 0.92%, respectively. All participants took the same diabetes drug during the study (2).
Summary Cinnamon may help lower blood sugar by making your cells more responsive to insulin.
American ginseng, a variety grown primarily in North America, has been shown to decrease post-meal blood sugar by about 20% in healthy individuals and those with type 2 diabetes (7).
Additionally, when people with type 2 diabetes took 1 gram of American ginseng 40 minutes before breakfast, lunch and dinner for two months while maintaining their regular treatment, their fasting blood sugar decreased 10% compared to those on a placebo (7).
Taking it: Take 1 gram up to two hours before each main meal — taking it sooner may cause your blood sugar to dip too low. Daily doses higher than 3 grams don’t appear to offer additional benefits (6).
Precautions: Ginseng can decrease the effectiveness of warfarin, a blood thinner, so avoid this combination. It may also stimulate your immune system, which could interfere with immunosuppressant drugs (6).
Summary Taking up to 3 grams of American ginseng daily may help lower fasting blood sugar and blood sugar after meals. Note that ginseng may interact with warfarin and other drugs.
Damage to your gut bacteria — such as from taking antibiotics — is associated with an increased risk of several diseases, including diabetes (9).
In a review of seven studies in people with type 2 diabetes, those who took probiotics for at least two months had a 16-mg/dl decrease in fasting blood sugar and a 0.53% decrease in A1C compared to those on a placebo (10).
People who took probiotics containing more than one species of bacteria had an even greater decrease in fasting blood sugar of 35 mg/dl (10).
How it works: Animal studies suggest that probiotics may decrease blood sugar by reducing inflammation and preventing the destruction of pancreatic cells that make insulin. Several other mechanisms may be involved as well (9, 10).
Taking it: Try a probiotic with more than one beneficial species, such as a combination of L. acidophilus, B. bifidum and L. rhamnosus. It’s unknown whether there’s an ideal mix of microbes for diabetes (10).
Precautions: Probiotics are unlikely to cause harm, but in certain rare circumstances they could lead to serious infections in people with significantly impaired immune systems (11).
Summary Probiotic supplements — especially those containing more than one species of beneficial bacteria — may help lower fasting blood sugar and A1C.
Aloe vera may also help those trying to lower their blood sugar.
Supplements or juice made from the leaves of this cactus-like plant could help lower fasting blood sugar and A1C in people with prediabetes or type 2 diabetes (6).
In a review of nine studies in people with type 2 diabetes, supplementing with aloe for 4–14 weeks decreased fasting blood sugar by 46.6 mg/dl and A1C by 1.05% (12).
People who had fasting blood sugar above 200 mg/dl before taking aloe experienced even stronger benefits (12).
Precautions: Aloe can interact with several medications, so check with your doctor before using it. It should never be taken with the heart medicine digoxin (15).
Summary Capsules or juice made from aloe leaves may help lower fasting blood sugar and A1C in people with prediabetes or type 2 diabetes. Yet, aloe may interact with several medications, most notably digoxin.
Berberine isn’t a specific herb, but rather a bitter-tasting compound taken from the roots and stems of certain plants, including goldenseal and phellodendron (16).
A review of 27 studies in people with type 2 diabetes observed that taking berberine in combination with diet and lifestyle changes reduced fasting blood sugar by 15.5 mg/dl and A1C by 0.71% compared to diet and lifestyle changes alone or a placebo (16).
The review also noted that berberine supplements taken alongside diabetes medication helped lower blood sugar more than medication alone (16).
How it works: Berberine may improve insulin sensitivity and enhance sugar uptake from your blood into your muscles, which helps lower blood sugar (17).
Taking it: A typical dose is 300–500 mg taken 2–3 times daily with major meals (17).
Precautions: Berberine may cause digestive disturbances, such as constipation, diarrhea or gas, which may be improved with a lower (300 mg) dose. Berberine may interact with several medications, so check with your doctor before taking this supplement (17, 18).
Summary Berberine, which is made from the roots and stems of certain plants, may help lower fasting blood sugar and A1C. Side effects include digestive upset, which may improve with a lower dose.
In one study, 72% of participants with type 2 diabetes were deficient in vitamin D at the start of the study (20).
After two months of taking a 4,500-IU supplement of vitamin D daily, both fasting blood sugar and A1C improved. In fact, 48% of participants had an A1C that showed good blood sugar control, compared to only 32% before the study (20).
Taking it: Ask your doctor for a vitamin D blood test to determine the best dose for you. The active form is D3, or cholecalciferol, so look for this name on supplement bottles (23).
Precautions: Vitamin D may trigger mild to moderate reactions with several types of medications, so ask your doctor or pharmacist for guidance (23).
Summary Vitamin D deficiency is common in people with type 2 diabetes. Supplementing with vitamin D may improve overall blood sugar control, as reflected by A1C. Be aware that vitamin D may interact with certain medications.
Gymnema sylvestre is an herb used as a diabetes treatment in the Ayurvedic tradition of India. The Hindu name for the plant — gurmar — means “sugar destroyer” (6).
In one study, people with type 2 diabetes taking 400 mg of gymnema leaf extract daily for 18–20 months experienced a 29% decrease in fasting blood sugar. A1C decreased from 11.9% at the start of the study to 8.48% (24).
Further research suggests that this herb may help lower fasting blood sugar and A1C in type 1 (insulin-dependent) diabetes and may reduce cravings for sweets by suppressing the sweet-taste sensation in your mouth (25, 26).
How it works: Gymnema sylvestre may reduce sugar absorption in your gut and promote cells’ uptake of sugar from your blood. Due to its impact on type 1 diabetes, it’s suspected that Gymnema sylvestre may somehow aid insulin-producing cells in your pancreas (6, 26).
Taking it: The suggested dose is 200 mg of Gymnema sylvestre leaf extract twice a day with meals (24).
Precautions: Gymnema sylvestre can enhance the blood sugar effects of insulin, so use it only with a doctor’s guidance if you take insulin injections. It may also affect blood levels of some drugs, and one case of liver damage has been reported (27).
Summary Gymnema sylvestre may lower fasting blood sugar and A1C in both type 1 and type 2 diabetes, though more research is needed. If you require insulin injections, it’s essential to consult your doctor before trying this supplement.
Low blood levels of magnesium have been observed in 25–38% of people with type 2 diabetes and are more common in those who don’t have their blood sugar under good control (28).
In a systematic review, eight of 12 studies indicated that giving magnesium supplements for 6–24 weeks to healthy people or those with type 2 diabetes or prediabetes helped reduce fasting blood sugar levels, compared to a placebo.
Furthermore, each 50-mg increase in magnesium intake produced a 3% decrease in fasting blood sugar in those who entered the studies with low blood magnesium levels (29).
Precautions: Avoid magnesium oxide, which can increase your risk of diarrhea. Magnesium supplements may interact with several medications, such as some diuretics and antibiotics, so check with your doctor or pharmacist before taking it (31).
Summary Magnesium deficiency is common in people with type 2 diabetes. Studies suggest that magnesium supplements may help reduce your fasting blood sugar.
When people with type 2 diabetes took 300, 600, 900 or 1,200 mg of ALA alongside their usual diabetes treatment for six months, fasting blood sugar and A1C decreased more as the dose increased (32).
How it works: ALA may improve insulin sensitivity and your cells’ uptake of sugar from your blood, though it may take a few months to experience these effects. It may also protect against oxidative damage caused by high blood sugar (32).
Taking it: Doses are generally 600–1,200 mg daily, taken in divided doses before meals (32).
Summary ALA may gradually help decrease fasting blood sugar and A1C, with greater effects at daily doses up to 1,200 mg. It also exhibits antioxidant effects that may reduce damage from high blood sugar. Still, it may interfere with therapies for thyroid conditions.
Chromium deficiency reduces your body’s ability to use carbs — converted into sugar — for energy and raises your insulin needs (35).
In a review of 25 studies, chromium supplements reduced A1C by about 0.6% in people with type 2 diabetes, and the average decrease in fasting blood sugar was around 21 mg/dl, compared to a placebo (6, 36).
A small amount of evidence suggests that chromium may also help lower blood sugar in people with type 1 diabetes (37).
How it works: Chromium may enhance the effects of insulin or support the activity of pancreatic cells that produce insulin (6).
Taking it: A typical dose is 200 mcg per day, but doses up to 1,000 mcg per day have been tested in people with diabetes and may be more effective. The chromium picolinate form is likely absorbed best (6, 36, 38).
Precautions: Certain drugs — such as antacids and others prescribed for heartburn — can reduce chromium absorption (35).
Summary Chromium may improve insulin action in your body and lower blood sugar in people with type 2 diabetes — and possibly those with type 1 — but it won’t cure the disease.
Many supplements — including cinnamon, ginseng, other herbs, vitamin D, magnesium, probiotics and plant compounds like berberine — may help lower blood sugar.
Keep in mind that you may experience different results than what studies have found, based on factors such as duration, supplement quality and your individual diabetes status.
Discuss supplements with your doctor, especially if you’re taking medicine or insulin for diabetes, as some of the above supplements may interact with medications and raise the risk of blood sugar dropping too low.
In some cases, your doctor may need to decrease your diabetes medication dose at some point.
Try only one new supplement at a time and check your blood sugar regularly to follow any changes over several months. Doing so will help you and your doctor determine the impact.