March 20, 2017
Diabetes Care
TAKE-HOME MESSAGE
- This analysis of data from 7333 adults (≥65 years) from the Third National Health and Nutrition Examination Survey (NHANES III) and Continuous NHANES was made to determine if HbA1c levels correlate with mortality in patients with diabetes. With a median follow-up of 8.9 years, 4729 (64.5%) of participants had died. Diabetics with elevated HbA1c levels were found to be at an increased risk of death. High levels of HbA1c in people with undiagnosed diabetes were also correlated with a higher risk of death in this study.
- These data indicate that increasing glycemic control may improve outcomes in people with diabetes over the age of 65.
Abstract
OBJECTIVE
Hemoglobin A1c (HbA1c) level has been associated with increased mortality in middle-aged populations. The optimal intensity of glucose control in older adults with diabetes remains uncertain. We sought to estimate the risk of mortality by HbA1c levels among older adults with and without diabetes.
RESEARCH DESIGN AND METHODS
We analyzed data from adults aged ≥65 years (n = 7,333) from the Third National Health and Nutrition Examination Survey (NHANES III) (1998-1994) and Continuous NHANES (1999-2004) and their linked mortality data (through December 2011). Cox proportional hazards models were used to examine the relationship of HbA1c with the risk of all-cause and cause-specific (cardiovascular disease [CVD], cancer, and non-CVD/noncancer) mortality, separately for adults with diabetes and without diabetes.
RESULTS
Over a median follow-up of 8.9 years, 4,729 participants died (1,262 from CVD, 850 from cancer, and 2,617 from non-CVD/noncancer causes). Compared with those with diagnosed diabetes and an HbA1c <6.5%, the hazard ratio (HR) for all-cause mortality was significantly greater for adults with diabetes with an HbA1c >8.0%. HRs were 1.6 (95% CI 1.02, 2.6) and 1.8 (95% CI 1.3, 2.6) for HbA1c 8.0-8.9% and ≥9.0%, respectively (P for trend <0.001). Participants with undiagnosed diabetes and HbA1c >6.5% had a 1.3 (95% CI 1.03, 1.8) times greater risk of all-cause mortality compared with participants without diabetes and HbA1c 5.0-5.6%.
CONCLUSIONS
An HbA1c >8.0% was associated with increased risk of all-cause and cause-specific mortality in older adults with diabetes. Our results support the idea that better glycemic control is important for reducing mortality; however, in light of the conflicting evidence base, there is also a need for individualized glycemic targets for older adults with diabetes depending on their demographics, duration of diabetes, and existing comorbidities.