Glycemic control and cardiovascular disease in 7454 patients with type 1 diabetes: an observational study from the Swedish National Diabetes Register (NDR)

  1. Björn Eliasson, MD, PhD1
  1. 1 Institute of Medicine, Sahlgrenska University Hospital, University of Gothenburg, Göteborg, Sweden
  2. 2 Department of Public Health and Caring Sciences/Family Medicine and Clinical Epidemiology, Uppsala University, Uppsala, Sweden
  3. 3 Department of Clinical Sciences, Lund University, University Hospital, Malmö, Sweden
  4. 4 Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Uppsala, Sweden
  5. 5 Center of Registers in Region Västra Götaland, Göteborg, Sweden

Abstract

Objective: We assessed the association between HbA1c and cardiovascular diseases (CVD) in an observational study of patients with type 1 diabetes followed for 5 years.

Research design and methods: 7454 patients from the Swedish National Diabetes Register, age 20-65 years, diabetes duration 1-35 years, followed from 2002 to 2007.

Results: Hazard ratios (HR) for fatal/non-fatal coronary heart disease (CHD) per 1%-unit increase in baseline or updated mean HbA1c at Cox regression were 1.31 and 1.34, and 1.26 and 1.32 for fatal/non-fatal CVD, all p<0.001 after adjustment for age, sex, duration, blood pressure, total-, LDL-cholesterol, triglycerides, BMI, smoking, and history of CVD. HR were only slightly lower for CHD (p=0.002) and CVD (p=0.002-0.007) after adjustment also for albuminuria. Adjusted 5-year event rates of CHD and CVD increased progressively with higher HbA1c ranging 5-12%, also when subgrouped by shorter (1-20 years) or longer (21-35 years) duration of diabetes. A group of 4816 patients with HbA1c 5-7.9% (mean 7.2%) at baseline showed risk reductions of 41% (15-60)% (p=0.005) for fatal/non-fatal CHD and 37% (12-55)% (p=0.008) for CVD, compared to 3268 patients with HbA1c 8-11.9% (mean 9.0%), fully adjusted also for albuminuria.

Conclusions: This observational study of patients in modern everyday clinical practice demonstrates progressively increasing risks for CHD and CVD with higher HbA1c independently of traditional risk factors, with no J-shaped risk curves. Baseline HbA1c mean 7.2% showed considerably reduced risks of CHD and CVD compared to 9.0%, emphasizing HbA1c as a strong independent risk factor in type 1 diabetes.

Footnotes

    • Received March 1, 2010.
    • Accepted April 17, 2010.

This Article

  1. Diabetes Care
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