ADA 2026: Could a Past GDM Diagnosis Signal Future T1D?

In an interview with Pharmacy Times, Jessica Dunne, PhD, US medical autoimmune diabetes medical director at Sanofi, discussed findings from a real-world longitudinal study examining type 1 diabetes (T1D) incidence following gestational diabetes mellitus (GDM) diagnosis, which was presented at the 2026 American Diabetes Association (ADA) Scientific Sessions in New Orleans, Louisiana. Dunne also was a co-author on data from the RECLASS-T1D study, which evaluated real-world reclassification rates among patients initially diagnosed with prediabetes or type 2 diabetes (T2D).

Dunne explained that up to 0.78% of women were diagnosed with T1D within 10 years of a GDM diagnosis and that women later found to have T1D tended to be younger and have lower body mass index (BMI) at the time of their GDM diagnosis.

She noted that while autoantibody testing during pregnancy raises some concerns, the 6-week postpartum visit represents a practical opportunity to screen higher-risk patients—particularly younger women who required insulin during pregnancy.

Dunne also emphasized the broader role pharmacists can play in recognizing atypical diabetes presentations and advocating for appropriate diagnostic testing. She outlined the 4 key T1D autoantigens—GAD65, IA-2, ZnT8, and insulin—and explained that 2 or more positive autoantibodies after confirmatory testing would place a patient in stage 1 T1D. Dunne noted that the primary barrier to correct diagnosis is not a lack of tools but rather the systematic underutilization of autoantibody testing and that pharmacists are well-positioned to help close that gap in practice.

Pharmacy Times: The GDM study found that women later diagnosed with T1D tended to be younger and had lower BMIs at GDM diagnosis. How actionable are those differences today—should clinicians be screening GDM patients more aggressively for T1D, and if so, how?

Jessica Dunne, PhD You know, I often say that pregnant women are the most compliant patients, and so, again, this also highlights something very actionable in my mind. Women with GDM are often already recognized as being at higher risk for developing diabetes later on, but they're all treated as if they are at high risk for T2D, and T1D is often overlooked.

There are some concerns about testing for antibodies during a GDM pregnancy, but potentially the 6-week postpartum visit is an ideal time to test women who had GDM for those autoantibodies. Again, we saw that younger patients were more likely to be at highest risk for developing later T1D. Things like insulin requirements during pregnancy matter too. I think—and this goes back to the RECLASS data—the more conditions we put on the criteria, the fewer patients we identify, obviously. Perhaps the starting point, again, is younger patients who were on insulin during their pregnancy. That would be a great place to start doing antibody testing in practice.

I think what you're kind of asking is, is this enough evidence to start driving practice change? I always think that if we're trying to do the best by our patients, then I would say yes. But maybe we need a real clinical study to actually show that this is feasible in a real clinic setting. What both of these studies drive home is that early identification really has positive benefits in terms of long-term outcomes and avoidance of diabetic ketoacidosis (DKA)—really identifying patients early and getting them on the right treatment early.

Pharmacy Times: What should pharmacists specifically understand about these findings when counseling patients with a history of gestational diabetes or an existing T2D diagnosis?

Dunne: I'm really glad you asked this question. I think pharmacists are going to play a key role moving forward in terms of this early identification of patients, not just in the GDM space but more broadly in terms of identification and potentially even early management of patients with diabetes. What both studies showed is that younger patients have a higher likelihood of developing T1D versus T2D—so again, GDM or prediabetes or T2D patients who are younger, under the age of 35. One of the other things we look at, although it was not captured in these studies, is whether they have a family history of autoimmune disease, and so I think those 2 factors—combined with, for GDM patients, whether they were on insulin during their pregnancy—are the most important considerations.

I'll let the data speak for itself in terms of a recommendation for antibody testing, but again, in order to move toward practice change, it's really the younger patients or those who required insulin rapidly within the context of their diagnosis. Those are the two main factors our studies showed were most important. In terms of what to request: the next step would be a comprehensive autoantibody panel, which can consist of the 4 known type 1 diabetes autoantigens—GAD65, IA-2, ZnT8, and insulin. Once those are positive, if t2 or more are positive after a confirmatory test, the recommendation is to move to glycemic monitoring. There is one caveat about the autoantibodies. The guidelines currently say that if you have 2 or more autoantibodies, you're in stage 1 T1D. What we don't yet have is enough data in adults to understand what autoantibody presentation looks like and the risk for T1D, because most of the studies we've done have been in kids. There is some data that a single autoantibody, especially in adults, may put you at higher risk for developing T1D.

What both of these studies have shown—and what other studies have shown—is that the real barrier to correct diagnosis is the systematic underutilization of autoantibody testing. It's not really about a lack of tools. Whether or not these studies can show that universal, risk-stratified screening makes sense at this point, pharmacists play a critical role in recognizing atypical presentations. They can be great advocates for appropriate testing and really ensure a proper diagnosis.