Myths vs facts: HbA1c and fatigue

HbA1c is a marker of average blood glucose over 2–3 months, not a direct cause of fatigue. A common myth is that elevated HbA1c directly causes tiredness. In reality, fatigue in diabetes can result from hyperglycemia, hypoglycemia, or comorbidities such as sleep apnea, depression, or nutrient deficiencies. A normal HbA1c does not rule out fatigue, which may have many other causes. The evidence linking HbA1c to fatigue is moderate: studies show an association, but causality is unclear. Clinically, HbA1c is a useful risk marker, not a direct driver of fatigue. Persistent fatigue warrants comprehensive evaluation beyond glucose control.