Hemoglobin A1c and glucose criteria identify different subjects as having type 2 diabetes in middle-aged and older populations: The KORA S4/F4 Study

Abstract

Objective. The American Diabetes Association (ADA) has recently recommended HbA1c for diagnosing diabetes as an alternative to glucose-based criteria. We compared the new HbA1c-based criteria for diagnosis of diabetes and prediabetes with the glucose-based criteria.

Research design and methods. In the population-based German KORA surveys (S4/F4) 1,764 non-diabetic participants aged 31–60 years and 896 participants aged 61–75 years underwent measurements of HbA1c, fasting plasma glucose (FPG), and 2-h glucose.

Results. Only 20% of all subjects diagnosed with diabetes by glucose or HbA1c criteria had diabetes by both criteria; for prediabetes, the corresponding figure was 23%. Using HbA1c ≥ 6.5%, the prevalence of diabetes was strongly reduced compared to the glucose criteria (0.7% instead of 2.3% in the middle-aged, 2.9% instead of 7.9% in the older subjects). Only 32.0% (middle-aged) and 43.2% (older group) of isolated impaired glucose tolerance (i-IGT) cases were detected by the HbA1c criterion (5.7% ≤ HbA1c < 6.5%).

Conclusion. By glucose and the new HbA1c diabetes criteria, different subjects are diagnosed with type 2 diabetes in middle-aged as well as older subjects. The new HbA1c criterion lacks sensitivity for impaired glucose tolerance.

Key words::

• Glycosylated hemoglobin A
• impaired fasting glucose
• impaired glucose tolerance
• normal glucose tolerance
• oral glucose tolerance test
• type 2 diabetes mellitus

Acknowledgements

We thank the field staff in Augsburg who were involved in the conduct of the studies.

Author contributions: Wolfgang Rathmann and Bernd Kowall contributed equally to the paper. W. Rathmann researched data and wrote manuscript. B. Kowall researched data and wrote manuscript. T. Tamayo contributed to discussion and reviewed/edited manuscript. G. Giani contributed to discussion and reviewed/edited manuscript. R. Holle contributed to discussion and reviewed/edited manuscript. B. Thorand contributed to discussion and reviewed/edited manuscript. M. Heier contributed to discussion and reviewed/edited manuscript. C. Huth contributed to discussion and reviewed/edited manuscript. C. Meisinger contributed to discussion and reviewed/edited manuscript.

Declaration of interest: The Diabetes Cohort Study was funded by a German Research Foundation project grant to the first author (DFG; RA 459/2-1). The German Diabetes Center is funded by the German Federal Ministry of Health, and the Ministry of Innovation, Science, Research and Technology of the State of North-Rhine-Westfalia. The KORA research platform and the KORA Augsburg studies are financed by the Helmholtz Zentrum München, German Research Center for Environmental Health, which is funded by the German Federal Ministry of Education, Science, Research and Technology and by the State of Bavaria. The authors declare no other conflicts of interest.