Higher HbA1c Levels May Increase Mortality Risk in Older Patients

Elevated HbA1c may increase mortality in older patients with diabetes.
Elevated HbA1c may increase mortality in older patients with diabetes.
Older patients with diabetes whose hemoglobin A1c levels were greater than 8% had an increased mortality risk.

Older patients with diabetes showed an increased risk of mortality when their hemoglobin A1c (HbA1c) levels were greater than 8%, according to recent research published in Diabetes Care.

Hsin-Chieh Yeh, PhD, from the department of epidemiology and division of general internal medicine at Johns Hopkins University School of Medicine in Baltimore, Maryland, and colleagues analyzed the relationship between HbA1c levels and all-cause as well as cause-specific mortalities, including cardiovascular disease (CVD), cancer, and non-cancer/non-CVD causes in 7333 patients with and without diabetes.

“Results from this analysis of a nationally representative sample of adults 65 years and older showed that the risk of all-cause, CVD, and cancer mortality appears to increase significantly above an HbA1c of 8.0% among older adults with diabetes,” the researchers wrote.

Patients evaluated from the Third National Health and Nutrition Examination Survey (NHANES III) (1998-1994) and Continuous NHANES (1999-2004) databases were at least 65 years of age and those patients without diabetes were further categorized into HbA1c <5.0%, HbA1c 5.0 to 5.6%, and HbA1c 5.7 to 6.4% groups. Patients were thought to have undiagnosed diabetes if they had a minimum HbA1c level of 6.5%, while patients with diagnosed diabetes were categorized into HbA1c <6.5%, HbA1c 6.5 to 6.9%, HbA1c 7.0 to 7.9%, HbA1c 8.0 to 8.9%, and HbA1c ≥9.0% groups.

“The current recommendations for older adults with diabetes put forth by the ADA [American Diabetes Association] suggest a reasonable HbA1c goal of <7.5% for healthy patients with few comorbidities and intact functional abilities,” the researchers wrote.

At a median 8.9-year follow-up, 4729 patients died, which included 2617 deaths caused by non-CVD or non-cancer, 1262 deaths caused by CVD, and 850 deaths from cancer. Of these, patients in the HbA1c 8 to 9% group (hazard ratio [HR], 1.6; 95% CI, 1.02-2.6) and HbA1c ³9% group (HR,1.8; 95% CI, 1.3-2.6) had a significantly higher all-cause mortality than patients with a minimum HbA1c level of 6.5% (P <.001). Compared with patients without diabetes and an HbA1c level of 5.0 to 5.6%, patients with diabetes and a minimum HbA1c level of 6.5% had a significantly higher mortality rate (HR,1.3; 95% CI, 1.03-1.8).

The researchers noted that updated consensus statements put forth by the American Diabetes Association (ADA) and American Geriatrics Society (AGS) recommend “potentially less aggressive glycemic goals” for older patients.

“The ADA and AGS both propose that glycemic goals should be individualized and depend on the patient’s health status, life expectancy, and personal goals. This recommendation is supported by our results, which showed differences in the risk of mortality across demographics, history of CVD, duration of diabetes, and type of antidiabetic medication use,” the researchers wrote. “Expanding on this current work, future studies should examine prospective associations between HbA1c control and diabetes-related health care utilizations and quality of life.”

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Palta P, Huang ES, Kalyani RR, et al. Hemoglobin A1c and mortality in older adults with and without diabetes: results from the National Health and Nutrition Examination Surveys (1988–2011) [published online February 21, 2017]. Diabetes Care. doi:10.2337/dci16-0042