Is HbA1c useful for Schlaf?

HbA1c is a long-term blood glucose marker reflecting average glucose over the past 2–3 months. Poor sleep can raise blood glucose via stress hormones (cortisol) and insulin resistance, so an elevated HbA1c may indirectly hint at sleep issues – but it is a very non-specific clue. The evidence is mechanistic: studies show short sleepers or those with poor sleep quality have higher HbA1c. However, HbA1c is not a direct sleep marker. For sleep assessment, sleep diaries, actigraphy, or polysomnography are far superior. A normal HbA1c does not rule out sleep disorders. Therefore, HbA1c can be useful as part of a general health check but not as a standalone indicator for sleep quality. Caveat: many factors (diet, exercise, genetics) influence HbA1c.