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Connecting diabetes phenotypes and COVID-19 outcomes

8th June 2021

Diabetes was identified as a risk factor for poor prognosis of COVID-19 early on in the pandemic. Research is now revealing a more nuanced association between levels of risk and phenotypic characteristics – work that could help identify which people with diabetes are at greater risk of developing severe COVID-19 or dying from the disease.

A number of systematic reviews and meta-analyses of COVID-19 outcomes have presented an approximate two- to threefold increased risk of death from COVID-19 among people with diabetes. Now, a novel systematic review and meta-analysis by Professor Michael Roden and a team from Düsseldorf, Germany has identified phenotype criteria of those living with diabetes associated with COVID-19 severity and mortality. Significantly, the study, which was published in Diabetologia in April, showed that more severe diabetes was associated with a poorer prognosis of COVID-19.

From four databases, 22 published studies – encompassing 17,687 people – were analysed for summary relative risks and certainty of evidence based on inclusion criteria. For deaths from COVID-19 in those with diabetes, the authors found a high-to-moderate certainty of evidence for associations with certain phenotypes. These included male gender, being over the age of 65 years, pre-existing comorbidities (including cardiovascular disease, chronic kidney disease and chronic obstructive pulmonary disease), diabetes treatment (including insulin or metformin dependence) and high blood glucose at admission.

Observations between risk phenotypes of diabetes and severity of COVID-19 were not as strongly or precisely determined. However, the estimated risk factors may be applicable for indicators of diabetes severity or for an overall poor health status; more studies on this subject will strengthen evidence and identify potential confounders.

Some results of existing studies are also affected by confounding bias and single studies are challenging to transfer to clinical practice. To further support this, studies of associations between COVID-19 severity and mortality and diabetes risk factors such as diabetes type, duration, HbA1c level and different glucose-lowering medications with laboratory markers (e.g. C-reactive protein and liver enzymes) are highly anticipated.

Click here to access the article in Diabetologia:

For more on this topic, see our series of short tutorials titled ‘COVID-19 and diabetes’, available in the Horizons section of this site.

The opinions expressed in this article are those of the author, Dr Eleanor D Kennedy.