Dr David McIntyre Discusses Prevalence of Gestational Diabetes

David McIntyre, MD, FRACP, describes different methods of diagnosing gestational diabetes around the world.

The prevalence of gestational diabetes varies depending on where you are, said David McIntyre, MD, FRACP, a professor of medicine and an endocrinologist at the University of Queensland in Brisbane, Australia.


What is the prevalence of gestational diabetes?

The prevalence actually varies very widely between different countries. And that's partly because of their underlying rates, principally, of type 2 diabetes. Obviously, GDM [gestational diabetes mellitus] is often a forewarner or a precursor of type 2 diabetes. When that happens, we see women both at risk of GDM during pregnancy and type 2 diabetes later. There's also a lot of dissent, I guess, or nonuniformity around the world in terms of which diagnostic approach to take. Some diagnostic approaches, even outside COVID-19, would lead to a prevalence of around about somewhere between 15% and 18% of women being affected by GDM.

The US sticking to the traditional model of having so called 2-step testing, and requiring 2 abnormal values on the GTT [glucose tolerance test] for a diagnosis, drops that number to around about 6% to 8%. Already pre–COVID-19, there were quite marked differences in what you call the prevalence of GDM. One of the things we did in the study was compare the differences pre–COVID-19 and then what would the rates be post-COVID-19. Certainly, the changes recommended in Canada and the United Kingdom would markedly drop that COVID-19 prevalence by something like 80%.

But the thing that we found in our study published last year in Diabetes Research and Clinical Practice was that that would also drop the number of complications actually detected or subject to treatment by about the same amount. So you will have less patients but you will be missing most of the outcomes you are trying to improve by having a diagnosis and treatment program.

Now, we also dealt separately with the Australian recommendations, which I was involved in. These used a different approach, where the woman would still have a fasting test in our laboratory and then the decision about whether to proceed to a glucose tolerance test would be made on the basis of that fasting test. That would mean that you would avoid something like, depending on where you are, 70% to even 90% of glucose tolerance test, but still have a reasonable safety profile. So that's where the Australian approach differed quite markedly from what was being recommended in other countries. Some places in Australia are still favoring that type of approach. Now I think because we have, luckily, very fortunately, we have a low COVID-19 environment, there's been a tendency to return to a standard testing basis with a glucose tolerance test.*

*This interview was conducted on June 23, 2021, prior to the increase in Australian COVID-19 cases seen in late June and early July.