If the mean blood glucose study does not generate adequate data—or if other factors intervene—the working group will consider other options. The simplest would be to do nothing, leaving the current A1c values in place. While that would mean continuing to report numbers that aren't totally accurate, it would have the distinct advantage of not rocking the boat.
Moreover, the current A1c values are directly traceable to outcomes from both the Diabetes Control and Complications Trial and the United Kingdom Prospective Diabetes Study, allowing for risk assessment for the diabetes-related complications observed in those landmark trials.
Far less likely is a decision to switch to reporting the lower IFCC numbers as percentages. Although some IFCC members had initially pushed for that, the majority have now come to realize that it would just cause too much confusion, Dr. Sacks said.
In addition, there is actually evidence to suggest that lowering the reported A1c values might even worsen diabetes control. A study done in Sweden, where reported A1c values were changed twice during the 1990s, showed that glucose control actually improved by about 0.5% among 49 children and adolescents when the reference scale was raised from an HPLC method with a normal range of 3.0% to 4.6% to the DCCT standard (normal range 4.1%–5.7%) in 1992.
But when the reference was lowered in 1997 to the Swedish national standard (normal range 3.1%–4.6%), the patients' control deteriorated by 0.5% and remained at that level for 2–3 years, despite extensive educational efforts. The findings suggest that “the psychological impact of the absolute numbers is very high when even small changes are made to the patients' reference levels,” Dr. Ragnar Hanas of Uddevalla Hospital, in Sweden, concluded (Diabetes Care 2002;25:2110–1).
Noted Dr. Sacks, “At this point, nobody thinks it's a good idea to lower the numbers. … Whatever we do, it will be done in such a way as to not compromise patient care.” However, he said, another option being considered is to report the new IFCC values in mmol/L, rather than as a percentage.
Alternatively, the working group could decide that both A1c and mean blood glucose be reported—either permanently or for a transition period—similar to the way laboratories now report both creatinine clearance and estimated glomerular filtration rate based on creatinine. How A1c would be reported in that scenario is also undecided. “It's not clear what will be reported. … All options are still on the table,” Dr. Sacks said.
The timetable for all this to happen is similarly hazy. Dr. Kahn believes it could occur as soon as the end of 2007 or early 2008, based on the assumption that the interim data to be presented in June will allow for a good prediction of the final results, while manufacturers have indicated it would take about 6–9 months to change the settings on the instruments.
But Dr. Sacks is more cautious, estimating that it would take at least a year beyond the final study report in September to analyze the results and, if a change is made, to undertake what will need to be a “huge public education effort.”
Dr. Kahn believes that a change to mean blood glucose would ultimately benefit patients, many of whom are still unclear as to how something called “hemoglobin A1c,” expressed as a small percentage, relates to the daily readings on their blood glucose monitors.
“People are doing meter readings and getting numbers like 130 or 150. … They say, 'What's that got to do with an 8?' It's all very confusing,” he said.
Dr. Kahn is already preparing for the public education campaign: “I have a book on how [the European Union] converted to the Euro. That's the best analogy.”
'Nothing will be changed without people being notified and given lots of preparation time.' DR. SACKS