After shock

Links between the presence of microvascular diabetic complications and worse outcomes in COVID-19 are well established. Now, however, new research suggests those linkages may reverberate way beyond the acute disease phase, compounding post-COVID syndrome.

In his presentation on the links between diabetic microvascular complications and COVID-19, Professor Rayaz Malik quotes a celebrated line from the Scottish poet Thomas Campbell: “Coming events cast their shadows before”. The coming events with which Rayaz is concerned are not just the acute effects of COVID-19, whose particular risks for people with diabetes are already so painfully familiar to us all. Here, his particular focus is on another condition that is gaining increasing recognition: long COVID or post-COVID syndrome.

As many as 2 to 10% of people who have recovered from COVID-19 are now thought to develop long COVID. Research into this relatively new aspect of COVID-19 and diabetes’ relationship is, necessarily, in its infancy – and is not a little complicated by what Rayaz terms the condition’s “somewhat nebulous” array of symptoms. Nevertheless, he is able to share findings from some fascinating studies.

“It’s difficult to work out a concrete disease entity underlying all this,” Rayaz explains. “But there is now evidence coming through to suggest that there may be a neurological hit at the time of COVID-19, which then persists in these people with long COVID. And one of those clues comes from a study that actually I’ve been involved in with Ariel Odriozola’s group in Barcelona, where we had a case series of patients who had diabetes but didn’t have any diabetic neuropathy or overt diabetic neuropathy before they had their COVID-19. But then, afterwards, they had really quite significant neuropathic symptoms.”

Another study Rayaz has been involved in, this time in Turkey, used the technique of corneal confocal microscopy to study people with long COVID – the same technique Rayaz pioneered the use of in diabetic neuropathy. Significantly, the technique revealed that people who have long COVID at four and 12 weeks have fewer corneal nerves and increased immune cells in their cornea.

No doubt further work will expand this area of research, helping us to develop a deeper understanding of aspects of post-COVID syndrome and their potential linkages to other disease pathways in diabetes. For now, though, Professor Malik’s presentation is an excellent place to gain some early insights into this emerging area of medicine.

Click here to watch Professor Malik’s complete presentation, ‘COVID-19, microvascular complications and long COVID’.