Interestingly at the moment of my question I still thought that T1 and T2 can not be confused for a longer period of time. But that is the problem and danger here. The professional field can make the same mistake easily. A T1 with high levels of residual beta cells will have a glucose control similar to a T2: higher mean, less spikes. Gradually the quality of control will degrade and this can lead to a long period of suffering - with DKA even death. So we have a relation of 44:56 in the identified group of T1 diabetics and many T1 diabetics in the class from 20-100 are not counted for because they are misdiagnosed as T2. Like you I think this can really mess up the statistics - even for T2. It would be really important to count and classify all diagnosed cases of diabetes and to establish protocols for the identification of these diseases. In Germany we have the same problem for the statistics: Diabetes is no reportable disease. At least we have Europe-wide Disease Management Programs (DMP). The patients are asked if they are willing to participate if they qualify for a DMP and I think most will do that. In the DMP specific standards for statistics and disease management are followed. These numbers can then be used as early warning indicators and for burden charing between health insurance companies.
Well actually, T1 and T2 can be confused forever. Think about it, the only definitive diagnosis of T1 occurs either from
(a) You arrive in the ER with sudden onset
(b) You get proper testing a full antibody panel and c-peptide
But from the studies I have seen, only 85-90% of T1s test positive for one or more antibodies, so 10-15% of T1s can be readily confused for T2s.
My P refused me all antibody tests and only granted me a single c-peptide after two years of pleading (it came in low). My GP believed that all T1s were sudden onset (and she was a recent grad). Today, I am still diagnosed T2. I've never been granted a full antibody panel (I was GAD negative) and I still have no confidence in my actual diagnosis.
And while we think that someone with slow onset won't respond to oral medications, they in fact often do respond pretty well. And T2 progresses, just like LADA will. There is good evidence that early application of insulin therapy for LADA preserves remaining beta cell function and has better outcomes. I actually believe the same principle applies to T2.
If only 85-90% of T1s test positive then
a) what is the standard error for these tests - the likelihood of false negatives?
b) I would suppose that there is a timeframe with high autoimmune activity that should not be missed. If I would have these test now I very likely would be negative because my beta cells are totally gone. I do not see any sign of beta cell activity in my numbers. So antibody tests need to be done in the early stages for diagnosis not later in life I think.
c) perhaps the missing 10-15% are in the mody subgroup?
I too was diagnosed randomly at a physical, and would also recomend the A1C for your daughter. You can buy them over the counter now.
I use LADA when talking to people who know. I have been called LADA, Adult Onset Type-1, Slow Onset Type-1, and just Type-1 by the white coats. Was 36 at DX, my mother was 32.