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. 2009;4(2):e4412.
doi: 10.1371/journal.pone.0004412. Epub 2009 Feb 11.

The true value of HbA1c as a predictor of diabetic complications: simulations of HbA1c variables

Marcus Lind  1 , Anders Odén, Martin Fahlén, Björn Eliasson
Affiliations

The true value of HbA1c as a predictor of diabetic complications: simulations of HbA1c variables

Marcus Lind et al. PLoS One. 2009.

Abstract

Aim: The updated mean HbA1c has been used in risk estimates of diabetic complications, but it does not take into account the temporal relationship between HbA1c and diabetic complications. We studied whether the updated mean HbA1c underestimated the risk of diabetic complications.

Method: Continuous HbA1c curves for 10,000 hypothetical diabetes patients were simulated over an average of 7 years. Simulations were based on HbA1c values encountered in clinical practice. We assumed that each short time interval of the continuous HbA1c curves had a long-lasting effect on diabetic complications, as evidenced by earlier studies. We tested several different HbA1c variables including various profiles, e.g. different duration, of such a long-lasting effect. The predictive power of these variables was compared with that of the updated mean HbA1c.

Results: The predictive power of the constructed HbA1c variables differed considerably compared to that of the updated mean HbA1c. The risk increase per standard deviation could be almost 100% higher for a constructed predictor than the updated mean HbA1c.

Conclusions: The importance of good glycemic control in preventing diabetic complications could have been underestimated in earlier hallmark studies by not taking the time-dependent effect of HbA1c into account.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Simulated HbA1c curves.
Two examples of simulated HbA1c curves. One of the patients was followed for 7.6 years (black curve) and the other patient for 10.0 years (red curve).
Figure 2
Figure 2. Correlation coefficient between HbA1c values at different points of time.
The estimated correlation coefficient between two HbA1c measurements from the same patient, as a function of the time between the measurements.
Figure 3
Figure 3. Study model of the temporal relationship between HbA1c and diabetes complications.
Relative contribution to the constructed variables at different periods after an HbA1c value was present. The time to maximal effect was A which was reached after a period of increase B and followed by a period of decrease C.
Figure 4
Figure 4. Gradients of risk.
Gradient of risk for the updated mean HbA1c and the corresponding estimated gradient for an assumed optimal HbA1c variable. The correlation coefficient between the constructed variables versus the updated mean ranged from 0.53–0.78 and the figure illustrates the cases 0.5, 0.6, 0.7 and 0.8.
See this image and copyright information in PMC

References

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