Tuesday, October 15, 2019

Retrospective #241: Should A1c Increase with Age?

The headline in Diabetes in Control reads “HbA1c Increases with Age.” Headlines like this are often evidence of confirmation bias and can be perilously misleading. So, I read the digest piece and then the abstract in the medical journal Diabetic Medicine. If you register and pay a big fee, you can get 24-hour online access to the full study from publisher Wiley.com. Such is the cost to society for dissemination of partially government-funded medical research.
Interestingly, it appears, on Diabetes in Control is guilty of confirmation bias. The medical journal is simply guilty of myopia. I say “it appears” because that is all I can afford. The full study could disabuse me of my take (and biases). That said, this study was a review of two data sets whose aim was “to determine whether using HbA1c for screening and management, in a “cross-sectional analysis in adults without known diabetes,the effects of aging have an impact on diagnostic accuracy.” That’s reasonable, and the researchers found some interesting, but unsurprising RESULTS.
My quarrel, then, is not with the researchers. It is with Diabetes in Control, and with their headline writer in particular. It is not nit picking to point out that the headline and the Diabetes in Control story are contradictory. Neither is it consistent with the AIM, RESULTS or CONCLUSION of the actual paper, as reflected in the ABSTRACT. In addition, disparities like this just cause me to get a bit unglued and go off on a rant, so hold on to your seat. It’s a brief one.
The study adjusted for covariates for a multitude of factors, such as race, BMI, etc, but not for treatment modality. Here’s where the myopia, or maybe just ignorance comes in. Everyone in both data sets received the same or a similar failed treatment plan, the ADA Standard of Care of Type 2 diabetes. So, naturally, everyone’s A1c increased as they got older! BREAKING NEWS: It was supposed to increase as they got older! The establishment medicine definition of diabetes is that it is a PROGRESSIVE disease. That means: Your condition will get worse as you get older IF YOUR DOCTOR FOLLOWS THE ADA STANDARD OF CARE. And as your condition gets worse, your A1c will get worse. Duh!!!
So, that’s where the digest failed. It just saw this result the way it was predisposed to see it. Except it was also careless; it describes the data sets as “adults with known diabetes,” not “without known diabetes.” A typo?
Another quibble I have is with the characterization that “the researchers found a remarkable decrement in the performance of the predictive value of A1c as compared with a 2-hour Oral Glucose Tolerance Test (OGTT), with age. Well, la dee dah. It shouldn’t come as news that the OGTT is and will always be the “gold standard” for screening for Type 2 diabetes. I had one in the 1980s. Have you ever had one? Do you know anyone at all who ever has had one?
But my quibble is not with the obvious superiority of the OGTT; it is with the term “remarkable decrement.” The Abstract provides some specificity. In elderly subjects without diabetes, over 10 years, their HbA1c’s increased less that 1/10th of one percent, whereas in an analysis of all elderly subjects, including those with diabetes on that failed treatment modality, their HbA1c increased by less than 1%. For reference, remember that the A1c Standard of Care for the general population of Type 2 diabetics is 7%, but in the elderly the ADA now sets the bar as high as 9% to “lessen the burden” on the patient. In my opinion, that’s just recognition and concealment of a failed medical policy.
Of course, the RESULT is that, bottom line, when treated to the ADA Standard of Care, as all the patients in both large subsets of data were, “both glucose intolerance and HbA1c levels increased with age.” In addition, “The specificity of HbA1c-based diagnosis criteria for prediabetes decreased substantially with increasing age.”
Clinical takeaway: one of the Diabetes in Control “practice pearls”: “Age should be taken into consideration when using HbA1c for the diagnosis and management of diabetes and prediabetes.” Is that because of a failed medical policy, your “progressive” disease will get worse with age, as everyone in the medical community has come to expect and accept? In other words, be prepared to raise the bar from an A1c of 7% to 9%. But it doesn’t have to be that way.
My recommendation: Everyone who has had 2 consecutive Fasting Blood Glucose tests ≥100mg/dl, or whose HbA1c is 5.7% or higher, is “Prediabetic” and should have a 2-hour Oral Glucose Tolerance Test to cement the diagnosis. Then, regardless of age, they should be advised to change their diet to dramatically reduce sugars and processed carbs.

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