Short-term impact of HbA1c on morbidity and all-cause mortality in people with type 2 diabetes: a Danish population-based observational study.
OBJECTIVE
In a population-based setting, we investigated whether diabetes-related morbidity and all-cause mortality within 2 years of HbA(1c) measurement were associated with that HbA(1c) level in individuals with type 2 diabetes. The main objective was to compare outcomes in those with HbA(1c) ≥ 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 HbA(1c), 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 HbA(1c) ≥ 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 HbA(1c) <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 HbA(1c) 6.0-6.9% (42-52 mmol/mol) at the lowest point. For diabetes-related morbidity, a dose-response pattern appeared (lowest for HbA(1c) < 5% [31 mmol/mol]). Patterns of HR differed with treatment modality.


CONCLUSIONS
An HbA(1c) level ≥ 7% (53 mmol/mol) was associated with increased morbidity and mortality. Both high and very low levels of HbA(1c) were associated with increased mortality. A dose-response pattern appeared for morbidity. The impact of HbA(1c) level on morbidity and mortality depended on treatment modality.
Department of Public Health, Health, Aarhus University, Bartholins Allé 2, 8000 Aarhus C, Denmark. mette.skriver@alm.au.dk
M V
MV
Skriver
H
H
Støvring
J K
JK
Kristensen
M
M
Charles
A
A
Sandbæk
D000368:Aged; D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000097:blood* / Q000401:mortality / Q000503:physiopathology; D003718:Denmark / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000401:mortality / Q000503:physiopathology; D003925:Diabetic Angiopathies / Q000097:blood* / Q000401:mortality / Q000503:physiopathology; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood* / Q000401:mortality / Q000503:physiopathology; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D012307:Risk Factors; D011795:Surveys and Questionnaires
D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human