Dr. Nikhil Tandon, Professor and Head, Department of Endocrinology and Metabolism, AIIMS Delhi, speaks exclusively to The Hindu and explains the relationship between COVID-19 and rise in blood sugar levels and its implications for patients.
Why do viral infections lead to elevated blood sugar levels?
Any infection or febrile illness can elevate blood sugar levels. It is basically a consequence of the mechanism that the body employs to fight the infection. In some cases, the medicines given to treat that infection may cause this rise in blood sugar levels.
When there is an increase in inflammatory markers, an extreme example of which is the “cytokine storm” in the case of COVID-19, it affects both the insulin release by the pancreas as well as the sensitivity of the tissue to insulin. Insulin facilitates the movement of glucose into tissues and any malfunctioning (either in production or tissue sensitivity) will lead to elevation of glucose levels in the blood.
In case of COVID-19, a patient with moderate to severe disease may need to be given steroids, which can also lead to an increase in the blood sugar levels of patients.
Is it difficult to treat diabetic COVID-19 patients?
In most cases, a person with well-controlled diabetes responds to the COVID-19 treatment the same way a non-diabetic does. However, in people with long-standing and poorly controlled diabetes, or those with diabetic complications such as kidney or heart disease, the management of COVID-19 can become more complex and the course of disease can be more severe, necessitating aggressive management, including the need for oxygen, ventilation and ICU care.
Conversely, the management of COVID-19 in such patients can make the treatment of diabetes more difficult. For example, steroids, which are an important part of COVID-19 treatment, can cause a significant worsening in blood sugar control. Hence, patients with diabetes invariably require treatment with intensive insulin regimens.
In addition to steroid therapy, there are a lot of other factors during the illness contributing to this rise in blood glucose levels, such as changes in the dietary pattern of a patient. Then the stress of the disease and the inability of a patient to follow the regular food and exercise regimen can also lead to increased blood glucose levels.
Can COVID-19 cause diabetes?
Diabetes is an asymptomatic disease in most people, so there could be a good number of people who may not be aware of their diabetes before they caught COVID-19. There are studies that state that in poorly resourced countries, as many as 50% people with chronic illness, such as diabetes, are undiagnosed. Several patients, even when they know that they have diabetes, are either unable to afford medical care or are not managing the disease well, resulting in only about 1 in 8 patients with diabetes having their blood sugar level optimally controlled.
Then there are people who may have had the tendency to develop diabetes, and COVID-19 has caused what we called stress hyperglycemia. In some patients, it could be a combination of stress hyperglycemia and medications such as steroids that can lead to an increase in blood sugar levels. And finally, there is an ongoing discussion about the possibility of COVID-19 disease itself causing new-onset diabetes in a patient.
Theoretically, COVID-19 can also cause diabetes as the pancreas have ACE2 receptors, which can enable SARS CoV2 to gain entry into the pancreatic beta cells, resulting in structural and functional damage. However, we need more data to support this.
So, when can we say that COVID-19 has caused diabetes?
At the time of COVID-19, if we do a test called HbA1c, which gives us average glucose of the previous three months, and if these levels are elevated, it means that the person had diabetes even before he contracted COVID-19. If the HbA1c was normal, we should reassess the blood glucose levels after the COVID disease has settled and the steroid therapy (if used) has been discontinued — the glucose levels will normalise if either the disease itself or steroid therapy contributed to the rise in blood sugar.
If the blood sugar remains high weeks after recovery from the acute disease or the cessation of steroids or both, it will raise the possibility of COVID having caused the diabetes.
And how does this knowledge help doctors treat their patients?
This test helps doctors know whether the elevated blood glucose levels in a COVID-19 patient are temporary, induced by the reasons we discussed or require long-term management of the disease. In the first case, the blood sugar levels become normal as soon as the person recovers from COVID, or when the steroids are stopped. These patients don’t require any medication to manage their blood sugar levels post their recovery.
What precautions should a diabetic person take if he or she catches COVID-19 to protect oneself?
Diabetes may lead to complications in the kidney, the heart, and eye. Such patients need to be much more careful and make every effort to keep their blood glucose levels under control. They need to be very particular about their diet, exercise and medication.
Most importantly, since such patients are at a higher risk of developing severe COVID-19 disease, they should take a vaccine. Vaccination significantly reduces the chance of severe disease and mortality.
If a diabetic contracts COVID-19, the person should inform a doctor about it immediately, who can decide the line of treatment.
