(HealthDay News) — Excess mortality risk is associated with both known diabetes and undiagnosed diabetes but not for prediabetes, with lowest risk at HbA1c levels from 5.4% to 5.6% and a significantly increased risk at ≤5.0% and ≥6.4%, according to a study published in Diabetes Care.

Rebecca Paprott, from the Robert Koch Institute in Berlin, and colleagues assessed the association between mortality and glycemic status in 6,299 participants aged 18 to 79 years participating in the German National Health Interview and Examination Survey 1998. 

Patients’ glycemic status was characterized as known diabetes (self-reported diagnosis or intake of antidiabetic medication); undiagnosed diabetes (≥6.5%); prediabetes with very high (6.0% to 6.4%) or high diabetes risk (5.7% to 5.9%); and normoglycemia (<5.7%). 

Mortality was assessed over an average of 11.6 years of follow-up.

The researchers observed a higher mortality risk in participants with known diabetes (HR=1.41; 95% CI, 1.08-1.84) and undiagnosed diabetes (HR=1.63; 95% CI, 1.23-2.17), but not for those with high (HR=1.02; 95% CI, 0.80-1.30) or very high diabetes risk (HR=0.87; 95% CI, 0.67-1.13). 

The investigators observed a U-shaped association, with lowest risk at HbA1c levels of 5.4% to 5.6% and a significantly increased risk at ≤5.0% and ≥6.4%.

“The observed U-shaped relationship adds to existing evidence that not only high but also low HbA1c levels might be associated with all-cause mortality,” the researchers wrote.


  1. Paprott R et al. Diabetes Care. 2014;doi:10.2337/dc14-1787.