Metabolic & Cardiometabolic · Gut & Microbiome

gut-microbiota-derived D-lactate worsens glucose metabolism

In plain terms: Does D-lactate made by gut bacteria worsen blood sugar control?

Insufficient Metabolic & Cardiometabolic 🐭 Non-human evidence

RefutedContestedStrong support

consensus score 0.25

⚖️ Thin evidence — read the needle loosely. The score shows which way the studies lean, but there are too few independent, high-quality ones to place it firmly. Expect this to move as better evidence arrives.

In obese mice, microbe-made D-lactate raised blood glucose and trapping it improved glucose, insulin and fatty-liver disease, but this is animal-stage evidence not yet shown in humans.

Evidence ladder

How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."

Top evidence so far: A plausible theory (Mechanism)

MechanismIn-vitroAnimalObservationalRCTMeta-analysis

How the studies fall

2 support 0 contradict 0 tested null 2 mixed · 4 sources, 2 independent groups

What the evidence shows

Norwitz **affirms** this claim. Consensus below reflects independent literature only.

The evidence (4)

Source	Grade	Stance	Quality	Finding
Fang 2025 · Cell Metab	animal	supports	high	Source paper: D-lactate higher in obese humans/mice; raised hepatic glucose; gut "D-lactate trap" polymer lowered glucose+insulin & MASH fibrosis in obese mice.
Busing 2023 · J Pediatr Gastroenterol Nutr	observational	mixed	low	Independent: gut microbiota composition drives circulating D-lactate (FMT alters it), corroborating microbial origin but not the glucose-dysregulation step.
Monroe 2019 · Nat Commun	mechanism	supports	moderate	Independent: LDHD loss-of-function raises human D-lactate, confirming a dedicated D-lactate metabolic pathway in humans (mechanistic plausibility).
Jain 2021 · Case Rep Gastroenterol	observational	mixed	low	Independent: clinical D-lactic acidosis ties high carbohydrate load + microbial D-lactate to systemic effects, but neurologic not glycemic; supports source not glucose.

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