People with Type 1 diabetes are roughly 3 times as likely to die of COVID-19 as the nondiabetic population, and are at a higher risk than those with Type 2 diabetes, according to a new study.
The study is the first we are aware of that explicitly analyzes the outcomes of people with Type 1 diabetes in the coronavirus pandemic. That people with Type 1 diabetes have such an increased rate of death is just one of several noteable conclusions. Poor blood sugar control and obesity were also found to contribute significantly to the risk of death. Advanced age, however, remains the single most important factor in severe COVID-19 outcomes.
The work, which comes from the UK and is funded by the National Health Service, actually has two linked papers: one in which mortality rates are analyzed in comparison to recent pre-pandemic levels, and another in which in-hospital COVID-19 deaths are scrutinized in particular. Outcomes of Type 2 diabetes were also addressed in detail (and will be discussed in a later article).
The graphic above shows the increase in rate of death, the degree to which it outpaces Type 2 and nondiabetic mortality rates, and how profoundly the risk of death is tied to age.
Researchers found that the rate of death in people with Type 1 diabetes in England was 148% higher than usual since the start of the pandemic. For reference, from March onwards death from all causes in England and Wales has increased by about 50%, which suggests that the risk of death for people diabetes is about three times as high as for people without, superficially confirming the conclusions of the researchers.
The study authors probed many different factors to draw conclusions that could help patients and doctors improve these outcomes.
One of the study authors, Partha Kar, gives a good quick summary of the study and its biggest takeaways in this Tweeted video:
— Partha S Kar (@parthaskar) May 20, 2020
Below, we’ll dig deeper into the findings:
With or without diabetes, age remains the single most powerful risk factor. The risk of death in patients with Type 1 diabetes tracks age curves among the nondiabetic population, with the danger increasing markedly at age 60 and climbing rapidly thereafter.
The very good news for those under the age of 49: deaths in the Type 1 community among that age group were rare enough that the precise number was actually suppressed due to privacy concerns. Those in their 40’s had 22% the rate of death as those in their 60’s, and patients under 40 were even less likely to die: the risk of death was seen to be only 3% that of those in the 60-69 cohort.
There were zero deaths recorded for people with Type 1 diabetes under the age of 20.
Blood Sugar Control
“In people with Type 1 diabetes, those with … poor glycaemic control had double the risk of people with good control.”
The study found a definitive link between blood sugar control, as assessed by A1c, and mortality. Increased risk was found to begin at an A1c of 7.5% (58mmol/mol) and rose thereafter.
There are many possible reasons why poor glycemic control may contribute to poorer outcomes. Whatever the precise mechanism, it’s not surprising to see that good control of the disease is likely to result in a more resilient response to COVID-19. ASweetLife has been beating this drum for months.
The study found a non-intuitive slight increase of mortality rate for patients with “tight” control, but it was not deemed statistically significant, and even if real could be due to any number of confounding factors unrelated to healthy glycemic control. Unfortunately, people with Type 1 diabetes that have achieved blood sugar control tight enough to resemble “normal,” as advocated by Dr. Richard Bernstein (among others), are rare enough that they don’t generally show up in significant samples in these types of surveys.
“The elevated risk of COVID-19 in people with diabetes and severe obesity is marked and adds to evidence that obesity is an important risk factor for death from COVID-19.”
Obesity (defined as a BMI > 30) increased mortality rate by 50%. And the heavier, the more dangerous: a BMI of > 40 more than doubled mortality rate. The authors conclude that “efforts to optimise obesity are likely important in order to reduce the adverse outcomes of SARS-CoV-2 infection.” These conclusions merely add to the growing evidence that obesity is an important risk factor.
There was an additional surprising finding: body weight exhibited a U-shaped risk curve in people with Type 1 diabetes. That means that even as obese patients experienced higher death rates, so did underweight patients. In fact, the lowest-risk bracket was actually a BMI of 25-29.9, which is officially labeled “overweight.” Those of normal or “healthy” weight were actually at a somewhat increased risk of death.
Why would people of normal or healthy weight be at greater risk of death? The authors suggest that some overlooked confounding factor could be at work. This is actually a familiar and famously confusing finding in such studies, nicknamed the obesity paradox. Rest assured, the study authors do not advise those of a healthy weight to pack on extra pounds. However, the risk to underweight people with diabetes may be worth paying attention to.
Other risk factors follow a similar pattern to what we already knew about COVID-19 outcomes.
Men with Type 1 are at significantly greater risk than women.
Black patients with Type 1 had a nearly doubled risk of death compared to white patients. Asian patients also saw a heightened risk.
Economic status, sadly, also plays a role: socio-economic deprivation correlates with higher death rates.
Previous conditions – such as heart disease and history of stroke – were also associated with higher mortality rates.
One study analyzed 418 Type 1 deaths, and the other 365. So, the samples are somewhat small.
The studies are also pre-prints, and had not yet been peer-reviewed or formally published when they were released on the internet yesterday. This is a practice that has become extremely common as the urgency of the coronavirus pandemic impels researchers cut through the slow traditional protocols.
As such, all the numbers discussed above must be considered provisional, and should be taken with a grain of salt. Nevertheless, it’s the best data we have yet about Covid 19 and Type 1 diabetes, and we felt it important to share these provisional data with our readers.