Our early understanding of the novel coronavirus, and the CDC recommendations that have largely driven American policy and behavior, were based almost entirely on the first reports to trickle out of Wuhan, China. It is now several months since that time, and as the virus itself has grown exponentially across the continents, so too has our data on its effects.
Some of our understanding has changed. High blood pressure, first identified as one of the major risk factors, may not be much of a factor after all. Obesity, not originally identified as a risk, has looked increasingly dangerous. And perhaps most surprising at all, smokers seem less likely to get sick or die of COVID-19. The virus remains mysterious.
The rate of infection has lately slowed across much of the Western world, the successful result of economic lockdowns, social distancing, and increased hygiene standards. It gives us a good opportunity to pause and consider the totality of evidence that we now have regarding COVID-19 and its interaction with Type 2 diabetes.
The largest and most detailed study that we are aware of was published as a pre-print last month, using data from the United Kingdom’s National Health Service. The study was executed in two parts. In the first (PDF), the researchers analyzed crude mortality data to get a wide view of how many people with diabetes were dying during the pandemic. Those numbers were striking: of the nearly 24,000 hospital deaths officially attributed to COVID-19, about 7,500 (31%) occurred in people with Type 2 diabetes. After adjusting for age and other factors, researchers determined that patients with diabetes were roughly twice as likely to die from COVID-19 complications as those without diabetes. That this level of risk is actually lower than early estimates may come as cold comfort.
The second part (PDF) dives into the details on these in-hospital COVID-19 deaths.
As it is for those without diabetes, advanced age is the one most overwhelming risk factor, with risks rapidly rising as age increases. Those over age 80 were about eight times as likely to die during COVID-19 hospitalization than those in their 50s. Likewise, men with Type 2 diabetes were more likely to die than women, another reflection of general trends. Other co-morbidities, such as a history of stroke or heart failure, also predictably increased the risk of death. Different races had different hazard ratios, with blacks experiencing the worst outcomes. Socioeconomic deprivation, sadly, also increased the likelihood of death.
The authors of these studies put their emphasis on conditions that we still have it within our power to change. They underlined this message in their conclusions:
“Hyperglycaemia and obesity in both Type 1 and Type 2 diabetes were independently associated with increased COVID-19 mortality. Risk factor control could diminish the impact of COVID-19 in diabetes.”
The prevention of hyperlgycemia – high blood sugar – has been identified by many as an absolutely critical element of COVID-19 prevention and control, even in those without diabetes. Therefore it may be unsurprising to learn that blood sugar control was found to be a significant factor in COVID-19 mortality. Among those with Type 2 diabetes, risks increased significantly as A1c’s rose above 7.5%.
Interestingly, the study also suggested that tight glucose control was actually associated with worse outcomes: those with an A1c below 6.5% fared slightly worse than those with an A1c between 6.5% and 7.5%. This is a counterintuitive finding, but it has been echoed in several major Type 2 diabetes studies.
Obesity was the second major factor isolated in the study. Severe obesity (BMI 40+) was found to be increase the hazard ratio by 64%. For patients below that level, however, the risks were not extreme. Those with Class 2 Obesity (BMI 35-40) were actually no more likely to die than those patients with “healthy” weight. This result confirms early CDC recommendations that categorized only the severely obese as “higher risk” patients. Those with Type 2 diabetes that were actually underweight were the most likely to die of all. (Underweight and T2 have long been known to be a “dangerous combo.”)
In summary, if you have Type 2 diabetes, the most significant risk factors – your age, gender, race and health history – are likely out of your hands. The single most important method we have of mitigating risk is to avoid infection in the first place: even as economies open back up, infection hygiene and social distancing should still be performed as much as possible.
For those with severe obesity and subpar blood glucose control, there is still time to ameliorate those risks through diet and lifestyle changes. Efforts to lose weight and lower blood sugar are likely to improve your ability to fight COVID-19.