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