Evidence check: Insulin in the context of fatigue

Insulin is central to energy metabolism; impaired insulin action (insulin resistance) can contribute to fatigue via inefficient glucose uptake and chronic blood sugar fluctuations. The provided context lacks direct studies on insulin and fatigue, only referencing isolated SNPs (e.g., ADRB2, MTNR1B) associated with metabolic traits. Evidence for a causal link between these variants and clinically relevant fatigue is weak (human-observational / GWAS). MyBody-X tests may include such markers, but their predictive value for personal fatigue is limited. Fatigue is multifactorial (sleep, stress, diet, exercise, mental health). A single genetic variant or insulin level cannot explain it. Caveat: Persistent fatigue warrants medical evaluation for insulin resistance or other causes (thyroid, iron deficiency).