Is HbA1c useful for Müdigkeit?

HbA1c is a well-established marker of average blood glucose over the past 2–3 months, primarily used for diagnosing and monitoring diabetes. In the context of fatigue (Müdigkeit), an elevated HbA1c may indicate undetected glucose dysregulation, which can contribute to tiredness through blood sugar swings or insulin resistance. However, fatigue is a highly nonspecific symptom with many potential causes (sleep deprivation, iron deficiency, thyroid dysfunction, psychological factors). A normal HbA1c does not rule out metabolic involvement, as prediabetic states can occur with normal HbA1c. The evidence for HbA1c's direct utility in fatigue is indirect and based on observational studies. Testing HbA1c may be reasonable if additional risk factors are present (e.g., obesity, family history of diabetes, elevated fasting glucose). Without such context, HbA1c alone is of limited value for fatigue evaluation. A comprehensive medical workup remains essential.