GradedHealth

Bitter Melon

Last reviewed October 2026 · Based on 22 studies

Bottom line

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 roughly 0.3 to 0.4 percentage points. Other reviews found no effect and the trial quality is low, so the evidence is limited. It can add to the effect of diabetes drugs.

What it helps with

  • Lowers fasting blood sugar — Mixed results, evidence grade C (Limited). Meta-analyses of small, short trials disagree; the 25-trial review rates certainty low with very high variation between trials; downgraded for inconsistency and risk of bias.
  • Lowers long-term blood sugar (HbA1c) — Mixed results, evidence grade C (Limited). Reviews disagree; the 25-trial review rates certainty very low with signs of publication bias that cut the effect by 65% when adjusted; downgraded for inconsistency and risk of bias.
  • Lowers insulin resistance — Benefit, evidence grade C (Limited). One meta-analysis of a few trials with very high variation, low certainty and a marker rather than a health outcome.
  • Lowers cholesterol and triglycerides — Mixed results, evidence grade C (Limited). Meta-analyses disagree and trials are short; cholesterol is a marker rather than a health outcome.
  • May cause low blood sugar, especially with diabetes medicines — Harm, evidence grade C (Limited). Based on narrative reviews and an observational survey rather than trials that measured hypoglycaemia; trials reported no serious adverse effects.

What it is

Bitter melon (bitter gourd, Momordica charantia) is a tropical fruit eaten as a vegetable and used in traditional medicine for diabetes. Trials have used juice, powder, capsules and extracts, sometimes mixed with other herbs [1].

How it might work

The 25-trial review proposes that bitter melon improves how the body responds to insulin rather than boosting insulin production, because it lowered insulin resistance but did not change a measure of insulin-making cell function [1]. The mechanisms it describes come from rodent and lab studies [1].

What the research says

A 2025 review of 25 randomised trials found lower fasting blood sugar, HbA1c, insulin and insulin resistance with bitter melon in people with prediabetes or type 2 diabetes [1]. Its results are on a combined scale, but earlier reviews report real units: HbA1c lower by 0.26 percentage points and fasting blood sugar lower by 0.72 mmol/L in 10 trials [2], and by 0.38 points and 0.85 mmol/L in eight trials [3]. Other reviews disagree: a 2023 review of nine trials found no significant change in fasting blood sugar or HbA1c [4], a 2014 review of four small trials found none [5], and a 2012 Cochrane review called the evidence insufficient [6]. The 25-trial review rates its own certainty low to very low, with wide variation between trials and signs of missing negative studies for HbA1c [1]. In head-to-head trials it lowered blood sugar less than metformin or glibenclamide [7][8]. In prediabetes, small trials report lower fasting glucose [9][10][11]. Reviews of cholesterol outcomes also disagree [12][4].

Doses used in studies

Trials used 300 to 600 mg a day of extract in prediabetes [11], 500 to 2,000 mg a day of powder in a 4-week type 2 diabetes dose test (only 2,000 mg clearly lowered the marker) [7], 2 to 4 g a day for 10 weeks [8] and 2.5 g of powder a day for 8 weeks in prediabetes [9]. These are what trials used, not recommendations, and products were not standardised [6].

Safety and interactions

Trials reported few serious adverse effects and mostly mild events [6][2][13]. Bitter melon may add to the effect of other glucose-lowering drugs and cause low blood sugar [14][15]; a Sri Lankan survey of 1,000 people with diabetes named bitter melon the most common non-prescribed native food behind low blood sugar, though a survey cannot prove cause [16]. A 2003 review lists hypoglycaemic coma in children, a favism-like syndrome and headaches among reported adverse effects, and reduced fertility in mice [14]. No upper intake limit has been set, and no good human data on pregnancy, breastfeeding or kidney or liver disease were found; the 2023 review found no change in liver enzymes or creatinine in trials [4]. People taking diabetes medicines should check with a doctor first.

Caveats and open questions

The reviews disagree, trials are short (4 to 16 weeks) and none measured complications or deaths [2][6]. Preparations differ, with no identical one tested twice in the early Cochrane review [6]. Trials directly testing low blood sugar with diabetes drugs are missing.

References

  1. Efficacy of Momordica charantia in glycaemic control and insulin resistance among patients with prediabetes and type 2 diabetes. A GRADE-adherent meta-analysis of randomised controlled trials.. Metabol Open, 2025.
  2. Momordica charantia L. lowers elevated glycaemia in type 2 diabetes mellitus patients: Systematic review and meta-analysis.. J Ethnopharmacol, 2019.
  3. Effects of Momordica charantia L. supplementation on glycemic control and lipid profile in type 2 diabetes mellitus patients: A systematic review and meta-analysis of randomized controlled trials.. Heliyon, 2024.
  4. The metabolic effect of Momordica charantia cannot be determined based on the available clinical evidence: a systematic review and meta-analysis of randomized clinical trials.. Front Nutr, 2023.
  5. The effect of bitter melon (Mormordica charantia) in patients with diabetes mellitus: a systematic review and meta-analysis.. Nutr Diabetes, 2014.
  6. Momordica charantia for type 2 diabetes mellitus.. Cochrane Database Syst Rev, 2012.
  7. Hypoglycemic effect of bitter melon compared with metformin in newly diagnosed type 2 diabetes patients.. J Ethnopharmacol, 2011.
  8. Lower hypoglycemic but higher antiatherogenic effects of bitter melon than glibenclamide in type 2 diabetic patients.. Nutr J, 2015.
  9. Bitter gourd reduces elevated fasting plasma glucose levels in an intervention study among prediabetics in Tanzania.. J Ethnopharmacol, 2018.
  10. Bitter gourd (Momordica charantia L.) supplementation for twelve weeks improves biomarkers of glucose homeostasis in a prediabetic population.. J Ethnopharmacol, 2025.
  11. Investigation of the Influence of a Bitter Melon Product on Indicators of Cardiometabolic Health in Adults with Prediabetes.. J Am Nutr Assoc, 2025.
  12. The Effects of Bitter Melon ( Mormordica charantia ) on Lipid Profile: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. Phytother Res, 2024.
  13. The effect of Momordica charantia capsule preparation on glycemic control in type 2 diabetes mellitus needs further studies.. J Clin Epidemiol, 2007.
  14. Bitter melon (Momordica charantia): a review of efficacy and safety.. Am J Health Syst Pharm, 2003.
  15. Natural Health Products and Diabetes: A Practical Review.. Can J Diabetes, 2017.
  16. Hypoglycaemia in diabetes: do we think enough of the cause? An observational study on prevalence and causes of hypoglycaemia among patients with type 2 diabetes in an out-patient setting in Sri Lanka.. BMC Endocr Disord, 2018.