I watched and listened to the 8/29 FDA meeting and have read a good deal about the inadequacy of the A1c metric to convey a comprehensive survey of what life is like with variable and out of range blood glucose. I fear our advocacy is a little too polite. We’re telling the regulators and the pharma companies that “the A1c number you cherish is OK, but we’d like to add a few more metrics, if we could, please.”
I think the A1c number provides a convenient and cheap way for pharma and regulators to reduce diabetes to a snapshot. The A1c has been validated to work for a population but seriously breaks down when it comes to individual people. According to the diaTribe 8/25 citation, an A1c of 6.0% can translate to an average blood glucose ranging from 100-152 mg/dl. What a joke!
For those of us fortunate enough to produce good numbers with a reasonable effort, we are plagued with the chronic endocrinologist warnings that our 6.0% (or less) A1c raises red flags about excessive hypoglycemia. It wasn’t until I could bring in CGM proof that my hypo excursions experience are rational and safe for a person who takes insulin did my endo back off with the stock beware of hypos cautions. Even then the doctor had to get in at least one warning remark per visit about hypos.
The basis of this seemingly required warning is not logical, at all. The unscientific endo mythology says that any person who takes insulin and has an A1c of 6.0% or less must be spending a lot of time hypo. Otherwise, they reason, how could they average out all that time they spend above 200 mg/dl?
I don’t think we should be pushing the FDA to accept some additional metrics for outcomes. I think we should be pushing them to demote the A1c to its rightful place, a substandard measure that hides lots of flaws. We should push for the superior metric of time in range as the gold standard of diabetes regimen efficacy.
Now I know that everyone does not wear a CGM. But when it comes to the big bucks washing around the pharma marketplace, we should at least insist that all trials use a CGM to document the claims that this new drug or device is better.
Time range is king. One number rolls in exposure to hypo- and hyper-glycemia as well as glucose variability. It hides nothing and is easy to understand. We need to replace the flawed A1c with time in range.