Myths vs facts: FUT2 and blood sugar

FUT2 (fucosyltransferase 2) determines secretor status: ~20 % of Europeans are non-secretors (rs601338 A allele). This alters gut microbiota composition because certain bacteria rely on fucosylated glycans. Some studies link non-secretor status to increased type 1 diabetes risk, but evidence for type 2 diabetes and fasting blood glucose is mixed. A meta-analysis (PMID 25855795) found no significant association with type 2 diabetes. Other studies report modest effects on HbA1c or insulin resistance, but effect sizes are small and not consistently replicated. Consumer DNA tests like MyBody-X may include FUT2 variants, but clinical relevance for blood sugar is unclear. FUT2 is one of many genetic factors; lifestyle, diet, and microbiome play larger roles. Bottom line: The claim that FUT2 directly determines blood sugar is a myth. A moderate, indirect influence via the microbiome is plausible but insufficient for personalized recommendations.