# Why are hypertension and diabetes patients at high risk of severe COVID-19?

Retrospective analysis of COVID-19 patient history showed that 12-22% and 23-30% of severe COVID-19 patients also had diabetes and hypertension, respectively (Guan et al., 2020; Yang et al., 2020; Zhang et al., 2020). This and other reports suggest that hypertension and diabetes are associated with a high risk of severe COVID-19 (Fang et al., 2020; Diaz et al., 2020).

The link between hypertension, diabetes and SARS-CoV-2 is angiotensin-converting enzyme 2 (ACE-2). ACE-2, expressed on lung, intestine, kidney and blood vessel epithelial cells, is one of the co-receptors SARS-CoV2 uses to infect cells. Levels of ACE-2 are higher in diabetes and hypertension patients compared to “healthy” individuals. This is due to the natural pathogenesis of the diseases, and treatment of these patients with either ACE-1 inhibitors or angiotensin-receptor antagonists, which further increases ACE-2 levels (Fang et al., 2020; Diaz et al., 2020). Based on this, researchers hypothesise that high levels of ACE-2, as observed in diabetes and hypertension patients, facilitate increased viral entry and replication leading to severe disease.

Interestingly, some researchers suggest treating severe COVID-19 with angiotensin receptor blockers (ARBs). At first, this may seem counterintuitive, however, they suggest treating with ARBs will increase ACE-2 which will then lead to increased levels of vasodilator angiotensin 1-7, reducing SARS-CoV2 pathogenesis (Gurwitz et al., 2020). This hypothesis is yet to be tested and proven.

Article by Cheleka AM Mpande

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