Association of HbA 1c levels with vascular complications and death in patients with type 2 diabetes: Evidence of glycaemic thresholds

Sophia Zoungas, John Chalmers, Toshiharu Ninomiya,, Qiang Li, Mark Cooper, Stephen Colagiuri, Greg Fulcher, Bastiaan De Galan, Stephen Harrap, Pavel Hamet, S Heller, Stephen MacMahon, Michel Marre, Neil Poulter, Florence Travert, Anushka Patel, Bruce Neal, Mark Woodward

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    182 Citations (Scopus)

    Abstract

    Aims/hypothesis: There is conflicting evidence regarding appropriate glycaemic targets for patients with type 2 diabetes. Here, we investigate the relationship between HbA 1c and the risks of vascular complications and death in such patients. Methods: Eleven thousand one hundred and forty patients were randomised to intensive or standard glucose control in the Action in Diabetes and Vascular disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial. Glycaemic exposure was assessed as the mean of HbA 1c measurements during follow-up and prior to the first event. Adjusted risks for each HbA 1c decile were estimated using Cox models. Possible differences in the association between HbA 1c and risks at different levels of HbA 1c were explored using linear spline models. Results: There was a non-linear relationship between mean HbA 1c during follow-up and the risks of macrovascular events, microvascular events and death. Within the range of HbA 1c studied (5.5-10.5%), there was evidence of 'thresholds', such that below HbA 1c levels of 7.0% for macrovascular events and death, and 6.5% for microvascular events, there was no significant change in risks (all p>0.8). Above these thresholds, the risks increased significantly: every 1% higher HbA 1c level was associated with a 38% higher risk of a macrovascular event, a 40% higher risk of a microvascular event and a 38% higher risk of death (all p<0.0001). Conclusions/interpretation: In patients with type 2 diabetes, HbA 1c levels were associated with lower risks of macrovascular events and death down to a threshold of 7.0% and microvascular events down to a threshold of 6.5%. There was no evidence of lower risks below these levels but neither was there clear evidence of harm. Trial Registration:: ClinicalTrial.gov NCT00145925 Funding:: Servier and the National Health and Medical Research Council of Australia (project grant ID 211086 and programme grant IDs 358395 and 571281)

    Original languageEnglish
    Pages (from-to)636-643
    Number of pages8
    JournalDiabetologia
    Volume55
    Issue number3
    DOIs
    Publication statusPublished - Mar 2012

    Keywords

    • Glycaemic control
    • Macrovascular disease
    • Microvascular disease
    • Mortality
    • Type 2 diabetes

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    Zoungas, S., Chalmers, J., Ninomiya, T., Li, Q., Cooper, M., Colagiuri, S., Fulcher, G., De Galan, B., Harrap, S., Hamet, P., Heller, S., MacMahon, S., Marre, M., Poulter, N., Travert, F., Patel, A., Neal, B., & Woodward, M. (2012). Association of HbA 1c levels with vascular complications and death in patients with type 2 diabetes: Evidence of glycaemic thresholds. Diabetologia, 55(3), 636-643. https://doi.org/10.1007/s00125-011-2404-1