What role does FUT2 play in blood sugar?

FUT2 (fucosyltransferase 2) determines secretor status and influences vitamin B12 absorption as well as gut microbiome composition. A direct role in blood sugar regulation is not strongly established. However, some evidence suggests that the non-secretor variant (e.g., rs601338) is associated with altered gut microbiota, which may indirectly affect glucose metabolism. GWAS have shown modest links to type 2 diabetes risk, but results are inconsistent and effect sizes are small. Lifestyle, diet, and other genetic factors dominate. Importantly, a DNA test cannot diagnose blood sugar issues; clinical blood tests (fasting glucose, HbA1c) are required. The evidence is primarily observational (GWAS) and mechanistic, not causal. B12 supplementation may be warranted for non-secretors, but not specifically for blood sugar control. Be cautious of marketing claims that overstate the metabolic impact of FUT2.