Does bitter melon lower blood sugar? A 25-trial review says yes, but earlier reviews disagree

Does bitter melon lower blood sugar? A 25-trial review found it did, modestly. Earlier reviews disagree, and the trials are mostly low quality.

Published November 2026

Short answer

Yes, modestly and uncertainly: a 25-trial review found lower blood sugar in people with prediabetes and type 2 diabetes, but other reviews found no effect, and the evidence is low quality. Evidence grade C (Limited). Meta-analyses of small, short trials disagree, and the 25-trial review rates its own certainty low to very low; downgraded for inconsistency and risk of bias.

Key takeaways

• A 2025 review pooling 25 trials in people with prediabetes or type 2 diabetes found lower fasting blood sugar, lower long-term blood sugar (HbA1c) and lower insulin levels with bitter melon [1].
• In earlier reviews that reported real units, bitter melon lowered HbA1c by about 0.26 to 0.38 percentage points and fasting blood sugar by about 0.72 to 0.85 mmol/L [2][3].
• Other reviews found no significant effect on blood sugar [4][5], and the 25-trial review itself rates its evidence low to very low certainty [1].
• In head-to-head trials, bitter melon lowered blood sugar less than metformin or glibenclamide [6][7].
• Reviews warn it may add to the effect of other glucose-lowering drugs, so people on diabetes medicine should check with a doctor first [8][9].

The short version

Does bitter melon lower blood sugar? Yes, modestly, according to a 2025 review of 25 trials in people with prediabetes and type 2 diabetes. People taking bitter melon ended up with lower fasting blood sugar, lower long-term blood sugar (HbA1c, the test that reflects your average over about three months) and lower insulin levels than people on placebo or comparison treatments [1]. But earlier reviews of the same question do not agree: two found a small drop and two found none [2][3][4][5]. The 25-trial review itself calls its evidence low to very low certainty [1].

What the studies show

The 25-trial review

The 2025 review pooled 25 randomised trials (counted as 34 comparisons) in adults with prediabetes or type 2 diabetes. Bitter melon was compared with placebo or a diabetes drug, and was given as juice, powder or capsules, sometimes mixed with other herbs [1]. Fasting blood sugar, HbA1c, insulin and a measure of insulin resistance (HOMA-IR) all came out lower, while a measure of how well the pancreas makes insulin did not change [1]. The review reports its results on a combined scale rather than in everyday units, so it cannot tell you how many points your HbA1c might drop [1].

How big is the drop?

Two earlier reviews reported real units. A 2019 review of 10 trials in 1,045 people with type 2 diabetes (4 to 16 weeks) found bitter melon lowered fasting blood sugar by 0.72 mmol/L, after-meal blood sugar by 1.43 mmol/L and HbA1c by 0.26 percentage points compared with placebo [2]. A 2024 review of eight trials in 423 people found drops of 0.85 mmol/L (fasting), 2.28 mmol/L (after meals) and 0.38 percentage points (HbA1c) [3]. A 2022 review of Ayurvedic medicines also put the HbA1c drop for bitter melon at about 0.3 points [10]. In one trial of 52 adults with prediabetes in Tanzania, 2.5 g of bitter gourd powder a day for eight weeks lowered fasting blood sugar by 0.31 mmol/L (5.6 mg/dL) compared with a cucumber placebo [11].

Where the reviews disagree

A 2023 review of nine placebo-controlled trials (414 people) found no significant change in fasting blood sugar or HbA1c and concluded the effect could not be determined [4]. A 2014 review of four small trials (208 people with type 2 diabetes) also found no significant drop [5], and a 2012 Cochrane review of four trials (479 people) with generally high risk of bias judged the evidence insufficient [12]. The authors of the 2025 review say the earlier null results came from very few trials or from mixing healthy, overweight and diabetic people in one analysis [1].

How solid is the 25-trial result?

Results varied a lot from trial to trial [1]. Three of the 34 comparisons were rated at high risk of bias, and many others did not explain how people were randomised [1]. The review rated its certainty low for fasting blood sugar, insulin and insulin resistance, and very low for HbA1c [1]. For HbA1c, the pattern of published studies suggested missing small negative studies, and adjusting for that shrank the effect by about two thirds (65%) [1].

Against diabetes drugs

In a four-week trial, 2,000 mg a day of bitter melon lowered a blood sugar marker (fructosamine) by 10.2 micromoles per litre, while metformin 1,000 mg a day lowered it by 16.8, so the effect was modest compared with the drug [6]. In a 10-week trial of 95 people, bitter melon at 2 g and 4 g a day lowered HbA1c and fasting sugar but had a weaker effect than glibenclamide [7].

People with prediabetes

In a 12-week trial of 75 adults with prediabetes, blood glucose rose by 3.35% on 300 mg a day of bitter melon extract and 1.05% on 600 mg a day, against 11.0% in the control group [13]. Another pair of trials found fasting glucose and insulin resistance lower after 12 weeks of 3.6 g a day of freeze-dried fruit in 38 people, but no difference in a four-week trial in 30 people [14].

The nuances

• Forms and doses vary. Trials used powder, juice, capsules and extracts, from 300 mg to several grams a day. In one dose test only 2,000 mg a day clearly lowered the marker, not 500 or 1,000 mg [6]. In a small three-month trial of 24 people, HbA1c fell within the group taking 2,000 mg a day [15]. The Cochrane review found that no identical preparation was tested twice [12].
• Short trials, no health outcomes. Most trials ran 4 to 16 weeks [2], and none looked at complications, deaths or quality of life [12].
• Low blood sugar with diabetes drugs. No trial in this search measured it directly. A pharmacy review notes that natural products that lower blood sugar can add to the effect of diabetes medicines and cause hypoglycaemia [9], and a 2003 review says bitter melon may have additive effects with other glucose-lowering drugs and lists hypoglycaemic coma in children among reported problems [8]. In a questionnaire survey of 1,000 people with diabetes in Sri Lanka, non-prescribed native foods accounted for low blood sugar in 16.9% of patients, and bitter melon was the most often named of them (54.5%), but a survey like this cannot prove cause [16].
• Other safety. Trials reported few serious problems and generally mild events [12][2][17]. The 2003 review lists a favism-like syndrome and headaches among reported adverse effects, and reduced fertility in mice [8]. No pregnancy data in people were found. See the Bitter melon page.

What this means for you

Bitter melon shows a small blood sugar lowering effect in the pooled trials, but not every review agrees, and in head-to-head tests it did less than standard drugs [1][4][6][7]. The trials used juice, powder or capsules [1]. If you take diabetes medicine, talk to your doctor or pharmacist before adding it, because the effects can add up [8][9]. For other herbs studied for blood sugar, see berberine, cinnamon and fenugreek.

Go deeper

• Bitter Melon — Bitter melon modestly lowered blood sugar in a 2025 review of 25 trials in prediabetes and type 2 diabetes, and two earlier reviews put the drop in HbA1c at ro…
• Berberine — Berberine meaningfully lowers fasting blood sugar and HbA1c in type 2 diabetes, with modest reductions in body weight.
• Cinnamon — Several meta-analyses report lower fasting blood sugar with cinnamon, mainly in type 2 diabetes.
• Fenugreek — Fenugreek seeds modestly lower HbA1c, a long-term blood sugar test, in people with type 2 diabetes, according to several meta-analyses.

References

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