Published in:
01-09-2012 | Article
Short-term impact of HbA1c on morbidity and all-cause mortality in people with type 2 diabetes: a Danish population-based observational study
Published in: Diabetologia | Issue 9/2012
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Aims/hypothesis
In a population-based setting, we investigated whether diabetes-related morbidity and all-cause mortality within 2 years of HbA1c measurement were associated with that HbA1c level in individuals with type 2 diabetes. The main objective was to compare outcomes in those with HbA1c ≥ and <7% (53 mmol/mol).
Methods
Individuals with type 2 diabetes from Aarhus County, Denmark, were identified from public data files in a 3 year period (2001–2003). Stratifying the 17,760 individuals by HbA1c, we estimated HRs for diabetes-related morbidities and all-cause mortality using Cox regression. Results were also stratified by treatment modality.
Results
In total, 1,805 individuals experienced at least one diabetes-related morbidity and 1,859 individuals died. In general, the HRs in adjusted analyses of diabetes-related morbidity and mortality were increased for HbA1c ≥ 7% (53 mmol/mol): morbidity, HR 1.48 (95% CI 1.34, 1.63); and mortality, HR 1.26 (95% CI 1.15, 1.39). On grouping individuals according to HbA1c <5% (31 mmol/mol), 5.0–5.9% (31–41 mmol/mol), 6.0–6.9% (42–52 mmol/mol), 7.0–7.9% (53–63 mmol/mol), 8.0–8.9% (64–74 mmol/mol) and ≥9% (75 mmol/mol), the HRs for mortality formed a U shape, with HbA1c 6.0–6.9% (42–52 mmol/mol) at the lowest point. For diabetes-related morbidity, a dose–response pattern appeared (lowest for HbA1c < 5% [31 mmol/mol]). Patterns of HR differed with treatment modality.
Conclusions/interpretation
An HbA1c level ≥7% (53 mmol/mol) was associated with increased morbidity and mortality. Both high and very low levels of HbA1c were associated with increased mortality. A dose–response pattern appeared for morbidity. The impact of HbA1c level on morbidity and mortality depended on treatment modality.