Evidence check: TCF7L2 in the context of Sport

TCF7L2 (transcription factor 7-like 2) is strongly associated with type 2 diabetes risk. The risk variant (e.g., rs7903146, T allele) impairs insulin secretion and sensitivity. In a sports context, this could affect carbohydrate metabolism and recovery, but direct evidence for performance impact is weak. The diabetes link is well-supported by GWAS and population studies (human-moderate). Caveat: Single gene variants have small effects; lifestyle, diet, and training status dominate. Genetic testing does not replace medical diagnostics.