COVID-19 and Diabetes Mellitus: The Link and Clinical Implications

Background: Coronavirus disease 2019 (COVID-19) is a pandemic viral infection that has ravaged the world in recent times, and the associated morbidity and mortality have been much more pronounced in those with noncommunicable disease. Diabetes mellitus is one of commonest noncommunicable diseases associated with worsening clinical status in COVID-19 patients. Summary: The aim of this review was to evaluate the receptors and pathogenetic link between diabetes and COVID-19. Both disease conditions involve inflammation with the release of inflammatory markers. The roles of angiotensin-converting enzyme molecule and dipeptidyl peptidase were explored to show their involvement in COVID-19 and diabetes. Pathogenetic mechanisms such as impaired immunity, microangiopathy, and glycemic variability may explain the effect of diabetes on recovery of COVID-19 patients. The effect of glucocorticoids and catecholamines, invasion of the pancreatic islet cells, drugs used in the treatment of COVID-19, and the lockdown policy may impact negatively on glycemic control of diabetic patients. The outcome studies between diabetic and nondiabetic patients with COVID-19 were also reviewed. Some drug trials are still ongoing to determine the suitability or otherwise of some drugs used in diabetic patients with COVID-19, such as dapagliflozin trial and linagliptin trial.