How does methylglyoxal in manuka honey affect insulin sensitivity and glucose metabolism?
Executive summary
Research and marketing materials paint conflicting pictures about methylglyoxal (MGO) in Manuka honey: manufacturers and some wellness sites highlight MGO’s antibacterial, anti-inflammatory and potential glycemic benefits (e.g., claims of improved insulin sensitivity and modest glycemic index advantages) [1] [2] [3], while clinical and review literature warns that MGO is a reactive dicarbonyl implicated in diabetic complications and may promote advanced glycation end‑products (AGEs) and insulin resistance in some settings [4] [5]. Available sources do not offer large, conclusive randomized trials proving that dietary MGO from Manuka honey improves insulin sensitivity in humans; the clinical commentary on diabetic wound care explicitly calls for RCTs to determine safety and efficacy [6] [5].
1. MGO: the molecule at the center of two narratives
Methylglyoxal is a highly reactive α‑dicarbonyl formed from sugars and from the conversion of dihydroxyacetone in Manuka nectar; it is widely accepted as the principal antibacterial constituent of Manuka honey and is the basis for MGO labelling on jars [4] [1] [7]. Producers and retail sites describe MGO as beneficial—antibacterial, anti‑inflammatory and a marker of potency—and highlight that Manuka honey has a lower, slower glycemic impact than refined sugar [1] [3] [2].
2. Claims that Manuka honey improves insulin sensitivity — what the promotional sources say
Several commercial and wellness outlets assert Manuka honey may enhance insulin sensitivity and help glycemic control, often attributing effects to anti‑inflammatory, antioxidant properties and a “balanced” sugar composition that blunts spikes [8] [2] [9] [3]. Some small human observations—cited by product sites—report altered glucose or insulin responses in tiny experimental settings (for example a 16‑person study referenced for aerosolized honey) but these are not presented as definitive clinical evidence and are reported by secondary sources rather than as large RCTs [10].
3. Scientific and clinical caution: MGO as a potential risk factor
Clinical reviews and toxicology summaries describe MGO as a reactive metabolite produced endogenously during glycolysis and implicated in the formation of AGEs, diabetic complications and vascular dysfunction; these sources frame MGO as a molecule that, in excess, is associated with insulin resistance and microvascular damage [4]. A focused commentary on Manuka honey and diabetic ulcers raises concern that the MGO content could delay wound healing in people with diabetes and explicitly calls for randomized controlled trials to assess safety and efficacy before endorsing routine use in this population [5] [6].
4. The evidence gap: small studies, product claims, and absent RCTs
Available sources show promotional sites extrapolating from biochemical properties or limited small studies to claim metabolic benefits [8] [2] [3]. At the same time, peer‑reviewed commentary and overviews stress MGO’s biological reactivity and links to pathology, and they call for more rigorous human trials [5] [4]. Multiple sources therefore note a lack of robust randomized clinical data demonstrating that dietary MGO from Manuka honey reliably improves insulin sensitivity in people with or without diabetes [6] [5].
5. Practical context for people with diabetes or insulin resistance
Manufacturers argue Manuka honey can be a lower‑GI alternative to refined sugar and may have ancillary anti‑inflammatory benefits, but it remains sugar and must be used in moderation [3] [2]. Clinical reviewers warn that MGO is biologically active in ways that could exacerbate AGE formation and vascular problems, and they flag specific concerns about using high‑MGO honey on diabetic wounds until safety is proven [5] [6] [4]. Consumers and clinicians must weigh small, suggestive human data and marketing claims against biochemical and preclinical signals of potential harm [8] [4] [5].
6. What responsible clinicians and researchers would do next
Top priorities are randomized controlled trials comparing Manuka honey (stratified by MGO content) with control sweeteners for insulin sensitivity, glycemic outcomes, and wound‑healing endpoints in people with diabetes; and mechanistic human studies measuring systemic MGO exposure, glyoxalase activity, AGE formation and inflammatory markers after realistic dietary doses [6] [4]. Until such data exist, claims that dietary MGO from Manuka honey improves insulin sensitivity should be treated as unproven marketing statements rather than established therapeutic effects [8] [5].
Limitations: sources provided include product and wellness sites alongside scientific review and clinical commentary; conclusions above reflect that mix and rely only on the cited materials. Available sources do not mention large, definitive randomized trials proving MGO from Manuka honey improves insulin sensitivity in humans [6] [5].