Who is at risk?
The most common characteristics of patients with diabetes who are affected by COVID-19 in addition to older age and multiple morbidities are uncontrolled glycaemia and obesity. 17-19 Diabetes and uncontrolled glycaemia have been previously reported as significant predictors of severity and mortality in patients with viral pneumonias.38-40 Infection with COVID-19 in people with diabetes may increase stress that leads to increased secretion of hyperglycaemic hormones such as glucocorticoids and adrenaline causing hyperglycaemia and fluctuating blood glucose levels. 41 The occurrence of hypoglycaemia due to variability of blood glucose levels may stimulate pro-inflammatory monocytes and increase platelet reactivity, contributing to a higher cardiovascular mortality in patients with diabetes. 42, 43 A recent study has shown that insulin infusion to tighten blood glucose control in patients with hyperglycaemia and hospitalised with COVID-19 has a protective effect. The study demonstrated that optimal glucose control in the immediate post-admission period for almost 18 days was associated with a significant reduction of inflammatory cytokines and pro-coagulant state which may reduce the risk of disease progression. 44Obesity is a common feature of patients with diabetes affected by COVID-19. In a small study of 49 outpatients with diabetes and COVID-19 the reported median BMI was 33.9 with a range that reaches as high as 63.9 Kg/m2. 31 Obesity is known to be associated with the severity and the longer duration of viral infections.45 Central obesity, which is the predominant type in individuals with diabetes, is particularly associated with higher risk due to the increased secretion of cytokines and chronic low-grade inflammation that may induce an impaired immune response.46 Other factors may be related to the fact that obesity may mechanically impair ventilation with reduced aeration of the lung bases therefore leading to accumulation of secretions and increased risk of infection. 47