Type 2 diabetes and Covid-19: Lessons learnt, unanswered questions and hints for the future

Type 2 diabetes (T2DM) and COVID-19 represent a considerable burden of disease for patients and healthcare systems. New evidence is transpiring detailing the existence of a bidirectional relationship between T2DM and COVID-19. Alongside the acute influence of pre-existing T2DM on the course of COVID-19 and the exacerbation of dysglycemia following acute infection, long-term sequalae resulting from the synergistic interplay between the two is emerging, namely the development of COVID-induced diabetes and long-COVID in patients with pre-existing diabetes. This review presents our current understanding of the bidirectionality between these two conditions with a view to highlighting questions which remain unanswered and suggesting avenues for future research. In doing so, it emphasises critical gaps where concentrated research efforts are likely to yield the most beneficial improvements in understanding of the relationship between the two conditions, translating to tangible optimisations in care for the affected population.