- HbA1c variability is strongly associated with overall mortality and emergency hospitalization and not explained by average HbA1c or hypoglycemic episodes.
- Targets should focus on both stability and absolute HbA1c level.
Why this matters
- Current guidelines promote both lower and stable HbA1c levels but tend to prioritize the former.
- UK primary care data for 58,832 patients with type 2 diabetes (T2D), 2006-2009.
- Funding: None.
- After adjustments, both higher and very low average HbA1c (7.16%), increasing variability, and positive or negative HbA1c trajectories were all associated with higher all-cause mortality.
- After adjustment for variability, average, and HbA1c trajectory, effect of average HbA1c seen only in the top 10% of HbA1c distribution (HR, 1.35; 95% CI, 1.24-1.47) for HbA1c >8.88% vs reference >6.09%-6.58%.
- By contrast, graded mortality risk increase was seen with increasing variability, ranging from HR of 1.32 (95% CI, 1.21-1.44) in 25th-50th percentile for coefficient of variation, to HR of 1.93 (95% CI, 1.72-2.16) in top 10th percentile.
- For coronary artery disease and ischemic stroke hospitalizations, risk increased for any HbA1c >7.16%.
- For the top 10% (>8.88%), the HR for hospitalization was 2.13 (95% CI, 1.91-2.37).
- Possible reverse causality, residual confounding.
- Short duration.