The association between glycated hemoglobin levels and mortality in non-diabetic elderly subjects

Background Glycated hemoglobin (HgbA1c) is extensively used as a screening tool for the diagnosis of diabetes mellitus (DM). Although its prognostic value among diabetics has been extensively studied, similar data among non-diabetics is scarce. The aim of this study was to evaluate the association between HgbA1c and mortality in non-diabetic elderly individuals. Methods A review of a computerized database of a large health care organization was performed. Non-diabetic individuals ≥ 65 years old with HgbA1c levels < 6.5% evaluated during the years 2002-2012 were included in the analysis. Subjects were stratified into quintiles based on HgbA1c levels. Hazard ratios (HR) for mortality were compared between the quintiles. Results The cohort included 12,937 non-diabetic individuals ≥ 65 years who did not develop DM during the follow-up period. The lowest mortality rate was observed in the fourth HgbA1c quintile [HgbA1c 5.9-6.1% (41-43 mmol/mol)]. Compared with the mortality rate in the fourth quintile, mortality rate was increased in the lowest (HgbA1c < 5.39%, 35 mmol/mol, HR 1.21 CI 1.09-1.35) and highest (HgbA1c > 6.11%, 43 mmol/mol, HR 1.17 CI 1.04-1.32) HgbA1c quintiles. This association persisted after adjustment for age, gender and co-morbidities. Conclusions The association between HgbA1c and all-cause mortality in non-diabetic elderly individuals has a U-shape form with the highest mortality in those with the lowest and highest HgbA1c levels.