Two recently published studies show how both type 1 and type 2 diabetes increase the risk of death from COVID-19 in a hospital setting. While previous studies have found that type 2 increases the risk of poor outcomes related to COVID-19, the fact that type 1 also does so is a notable finding — and seems to contradict anecdotal reports that people with type 1 may be at lower risk for COVID-19 or poor outcomes.
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Both studies were conducted by NHS England, and were led by the healthcare system’s national clinical director for diabetes and obesity. They’re based on data from the same group of people, and were published in the journal The Lancet Diabetes & Endocrinology.
Increased COVID-19 death risk due to diabetes
The first study looked simply at the risk of dying from COVID-19 and its complications within hospitals in the NHS system, and how having type 1 or type 2 diabetes affected that risk.
Out of over 61 million people who were alive and in the NHS system on February 16, 2020, 4.7% had a diagnosis of type 2 diabetes, while 0.4% had type 1 diabetes. During the study period between March 1 and May 11, there were 23,698 in-hospital deaths related to COVID-19 within the study group. About a third of these deaths were of people with diabetes: 31.4% were of people with type 2 diabetes, while 1.5% were of people with type 1 diabetes.
Once researchers adjusted for differences in age, sex, socioeconomic status, ethnicity and geographic region, they found that compared with people without diabetes, those with type 2 diabetes were 2.03 times as likely to die of COVID-19, while those with type 1 diabetes were 3.51 times as likely. When the researchers also adjusted for previous hospital admissions for cardiovascular problems, the relative risk of death dropped to 1.80 for type 2 diabetes and 2.86 for type 1 diabetes.
Without any statistical adjustments, the number of COVID-19 deaths per 100,000 people was 27 for people without diabetes, 138 for those with type 1, and 260 for those with type 2.
Other factors in COVID-19 death risk
The second study looked at factors that raised or lowered the risk of death from COVID-19 among people with diabetes, both type 1 and type 2.
Among people with diabetes hospitalized for COVID-19, those with an HbA1c level (a measure of long-term blood glucose control) of 10.0% or higher were significantly more likely to die than those with an HbA1c level of 6.5% to 7.0%. People with type 2 diabetes were 1.61 times as likely to die based on this higher HbA1c, while those with type 1 diabetes were 2.23 times as likely to die.
Due to the smaller numbers of people with type 1 diabetes in the study group, the researchers couldn’t make any conclusions about a significantly higher risk of death based on an HbA1c between 7.0% and 10.0% in this group. But among people with type 2 diabetes, compared with an HbA1c of 6.5% to 7.0%, those with an HbA1c of 7.6% to 8.9% were 1.22 times as likely to die of COVID-19, while those with an HbA1c of 9.0% to 9.9% were 1.36 times as likely to die.
In contrast with the higher risk of death associated with higher HbA1c, the researchers found that when it came to body weight, it was best to be somewhere in the middle.
Among people with type 1 diabetes who were hospitalized for COVID-19, those with a body-mass index (BMI, a measure of body weight that takes height into account) of 25.0 to 29.9 had the lowest risk of death. In comparison, those with a BMI below 20.0 were 2.45 times as likely to die, while those with a BMI of 40.0 or higher were 2.33 times as likely to die. For type 2 diabetes, the relative risk was 2.33 for a BMI below 20.0 and 1.60 for a BMI of 40.0 or higher.
The researchers also found that in both type 1 and type 2 diabetes, factors that increased the risk of death from COVID-19 included male sex, older age, impaired kidney function, being nonwhite, lower socioeconomic status, and previous stroke or heart failure.
Taken together, these studies suggest that people with type 1 or type 2 diabetes — especially those with other factors that increase their risk — are especially vulnerable to death from COVID-19 if they’re hospitalized for the infection.
Want to learn more about coronavirus and diabetes? Read “Coronavirus and Diabetes: What You Need to Know,” “Healthy Eating During Hard Times” and “Avoiding Coronavirus With Diabetes: Stock Up and Stay Home, CDC Says.”