Diabetes Is Increased After Mild Covid-19

Long Covid after “mild” infection is common, can be devastating and can last for a long time. Among the Long Covid syndromes are intense fatigue, brain fog, sleep difficulties, fevers, GI disturbances, mental and neuro syndromes such as anxiety and depression, headaches, along with heart damage and heart rate irregularities. In this 4th in this series on Long Covid, I will review the evidence that new onset diabetes can occur among patients who have had only mild Covid.

It might not be too much of a surprise to learn that people with very severe COVID-19 who were hospitalized or were in the intensive care unit have developed later diabetes. But the finding of diabetes after a mild infection was unexpected.

Two recent studies, one from Germany and the other from the United States, among others, drive home the point.

The German study looked at a cohort analysis from the “Disease Analyzer,” a national database from 1171 primary care physicians throughout Germany. The timeframe was March, 2020 to January, 2021, a time when few were vaccinated, and covered 8.8 million patients.

There were 35,865 individuals with documented COVID-19 during the study period. A control group with an equal number of individuals who had an acute upper respiratory infection (URI or “viral cold”) was matched for demographics and clinical characteristics. The two groups were similar for sex, age, health insurance index, month of COVID-19 or a URI and for comorbidities such as obesity, hypertension, hyperlipidemia, myocardial infarction and stroke. New onset diabetes was recorded from shortly after infection onset until July, 2021.

Type 2 diabetes, but not Type 1, was found to be increased among the Covid patients compared to the controls, 15.8 versus 12.3 per 1000 person years.

The graph above portrays the onset of diabetes over the 12 months observation period, the red line for those with a URI and the blue line for those with COVID-19. The absolute numbers are small but the difference, especially over time becomes clear.

The authors conclude that “COVID-19 confers an increased risk for Type 2 diabetes.”

The American study utilized the electronic medical record database of the Veterans Administration health system. They selected a cohort of about 181,000 individuals who had a positive test for Covid between March 1, 2020 and September 30, 2021 and who survived at least 30 days. They also created two control groups. The first or concurrent controls were about 4.2 million VA patients during the same timeframe and the second or historical controls were about 4.2 million veterans seen between March 1, 2018 and September 20, 2019, i.e., before the pandemic.

All of these individuals had no evidence of diabetes at the onset of the study period. The concurrent control group individuals had no positive tests for COVID-19 but it’s possible, in fact likely, that some had asymptomatic infection or were infected but never were seen in the VA system for their infection. All were followed for approximately one year. The numbers of individuals who developed diabetes were determined and compared between the Covid-19 patients and the two control groups.

All three groups were quite similar for multiple baseline characteristics. The average (but with wide ranges) age was about 61- 62 years, about three quarters were white, and 88% were male. The average BMI was 29. They were equally represented by blood pressure levels, cardiovascular disease, cerebrovascular disease, chronic lung disease, and dementia.

Taking the contemporary control group as a baseline, those who had COVID-19 had an excess of diabetes detected over the next 12 months.

Those individuals who at baseline had a higher diabetes risk score were substantially more likely to develop diabetes during those next 12 months. Diabetes onset was also more common among those who were greater than 65 years of age, those who had prediabetes as measured by HbA1c (a measure of blood sugar over time) and those with a BMI >30.

Those with more severe Covid-19 who were admitted to the hospital and those who were admitted to intensive care has substantially more diabetes develop than did those who had only mild Covid-19.

The risk for developing diabetes among the ~162,000 non-hospitalized individuals when considered as an excess burden above that of the concurrent control group was about eight per 1000 people at the end of 12 months. That may not sound like a big risk but it equates to about 1500 excess cases of diabetes among those not hospitalized with Covid, i.e., those with relatively mild Covid-19.

As the study authors noted, “Given the large and growing number of people infected with Covid-19…, these absolute numbers might translate into a substantial overall population level burden and could further strain an already overwhelmed healthcare system.”

These two reports demonstrate that diabetes is one more syndrome/disease that occurs after even mild Covid-19, another addition to the Long Covid pantheon. It is a reminder that even mild Covid-19 infection can lead to many later “Long Covid” syndromes and diseases. Patients and physicians need to be cognizant of the possibility that new onset diabetes might be related to prior Covid infection within the last year or so.