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Associations between haemoglobin A 1c and mortality rate in the KORA S4 and the Heinz Nixdorf Recall population‐based cohort studies
Author(s) -
Kowall Bernd,
Rathmann Wolfgang,
Kuß Oliver,
Herder Christian,
Roden Michael,
Stang Andreas,
Erbel Raimund,
Huth Cornelia,
Thorand Barbara,
Meisinger Christa,
Jöckel KarlHeinz,
Peters Annette
Publication year - 2021
Publication title -
diabetes/metabolism research and reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.307
H-Index - 110
eISSN - 1520-7560
pISSN - 1520-7552
DOI - 10.1002/dmrr.3369
Subject(s) - medicine , demography , confidence interval , cohort , population , diabetes mellitus , cohort study , relative risk , odds ratio , endocrinology , environmental health , sociology
Background There is limited knowledge about mortality risk in persons with increased haemoglobin A 1c (HbA 1c ) levels below the diabetes threshold. Moreover, little is known about how associations between increased HbA 1c and mortality depend on the length of follow‐up. Therefore, we studied associations between HbA 1c and mortality over long‐term follow‐up in persons with and without known diabetes. Methods We used data from two German population‐based cohort studies: KORA S4 Study (Southern Germany, n = 1458, baseline visits in 1999 to 2001, baseline age 55 to 74 years, mortality follow‐up 16.8 years) and Heinz Nixdorf Recall (HNR) Study (Ruhr area, n = 4613, baseline visits in 2000 to 2003, baseline age 45 to 75 years, mortality follow‐up 17.8 years). Adjusted log‐linear models were fitted to estimate relative risks (RRs) with 95% confidence intervals (CI). Results In both cohorts, participants with HbA 1c 39 to 41 mmol/mol (5.7%‐5.9%) and HbA 1c 42 to 46 mmol/mol (6.0% to 6.4%) did not have a larger overall mortality risk than participants with HbA 1c < 39 mmol/mol (5.7%): the corresponding adjusted RRs were 1.00 (95% CI: 0.83‐1.21) and 1.01 (0.80‐1.27) in KORA and 0.99 (0.82‐1.21) and 0.83 (0.65‐1.07) in the HNR Study. For the pooled cohorts, the RR for HbA 1c 39 to 46 mmol/mol (5.7%‐6.4%) was 0.96 (0.85‐1.07). Associations between newly detected diabetes (HbA 1c ≥ 6.5%) and mortality were weak after 4 and 8 years of follow‐up, but were stronger after 12 years of follow‐up, whereas associations between previously known diabetes (baseline) and mortality decreased. Conclusions HbA 1c ‐defined pre‐diabetes is not associated with overall mortality. For newly detected and previously known diabetes, mortality risks vary with length of follow‐up.