Aims/hypothesis: There is controversy regarding the performance of HbA1c in old age. We evaluated the prognostic value of HbA1c and other glycaemic markers (fructosamine, glycated albumin, fasting glucose) with mortality risk in older adults (66–90 years). Methods: This was a prospective analysis of 5636 participants (31% with diagnosed diabetes, mean age 76, 58% female, 21% black) in the Atherosclerosis Risk in Communities (ARIC) study, baseline 2011–2013. We used Cox regression to examine associations of glycaemic markers (modelled in categories) with mortality risk, stratified by diagnosed diabetes status. Results: During a median of 6 years of follow-up, 983 deaths occurred. Among older adults with diabetes, 30% had low HbA1c (<42 mmol/mol [<6.0%]) and 10% had high HbA1c (≥64 mmol/mol [≥8.0%]); low (HR 1.32 [95% CI 1.04, 1.68]) and high (HR 1.86 [95% CI 1.32, 2.62]) HbA1c were associated with mortality risk vs HbA1c 42–52 mmol/mol (6.0–6.9%) after demographic adjustment. Low fructosamine and glycated albumin were not associated with mortality risk. Both low and high fasting glucose were associated with mortality risk. After further adjustment for lifestyle and clinical risk factors, high HbA1c (HR 1.81 [95% CI 1.28, 2.56]), fructosamine (HR 1.96 [95% CI 1.43–2.69]), glycated albumin (HR 1.81 [95% CI 1.33–2.47]) and fasting glucose (HR 1.81 [95% CI 1.24, 2.66]) were associated with mortality risk. Low HbA1c and fasting glucose were no longer significantly associated with mortality risk. Among participants without diabetes, associations of glycaemic markers with mortality risk were less robust. Conclusions/interpretation: Elevated HbA1c, fructosamine, glycated albumin and fasting glucose were associated with risk of mortality in older adults with diabetes. Low HbA1c and fasting glucose may be markers of poor prognosis but are possibly confounded by health status. Our findings support the clinical use of HbA1c in older adults with diabetes. [Figure not available: see fulltext.].
Bibliographical noteFunding Information:
The Atherosclerosis Risk in Communities study has been funded in whole or in part with Federal funds from the National Heart, Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services, under contract numbers (HHSN268201700001I, HHSN268201700002I, HHSN268201700003I, HHSN268201700005I, HHSN268201700004I). Research reported in this publication was supported by the NIH/NHLBI grant T32HL007024 (MRR), NIH/NIDDK grants F30DK120160 (OT), K24DK106414 (ES) and R01DK089174 (ES). Reagents for the fructosamine assays were donated by Roche Diagnostics, and reagents for the glycated albumin (albumin) assays were donated by the Asahi Kasei Corporation. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The study sponsor/funder was not involved in the design of the study; the collection, analysis and interpretation of data; writing the report; and did not impose any restrictions regarding the publication of the report. Acknowledgements Author’s relationships and activities
The authors thank the staff and participants of the ARIC study for their important contributions. Parts of this study were presented as an abstract at the American Heart Association Epi|Lifestyle Scientific Sessions in Phoenix, AZ, USA, from 3?6 March 2020. The authors declare that there are no relationships or activities that might bias, or be perceived to bias, their work.
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