People with type 2 diabetes who take metformin or a sulfonylurea (such as glyburide, glipizide, or glimepiride) to lower their glucose levels may have a lower risk of death from COVID-19, while those who take insulin may have a higher death risk, according to an article published in the journal Frontiers in Endocrinology.
Since almost the start of the COVID-19 pandemic, researchers have known that people with diabetes are at greater risk for poor outcomes related to the viral infection — such as hospitalization, admission to the intensive care unit (ICU), and death. But it has long since emerged that not all people with diabetes are at equal risk for these outcomes. In fact, research has shown that high blood glucose is a better predictor of severe COVID-19 than diabetes is — suggesting that people with diabetes who keep their blood glucose well controlled may not be at much greater risk for poor COVID-19 outcomes. Other studies have shown that among people with diabetes, older age, being male, a higher body-mass index (BMI, a measure of body weight that takes height into account), having neuropathy, and taking the diabetes drugs SGLT2 inhibitors may raise the risk for severe COVID-19.
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Certain classes of diabetes medicine linked to lower COVID-19 death risk
For the latest analysis, researchers looked at 18 studies that included data on diabetes medications and deaths from COVID-19. These studies had a total of 17,338 participants, and there was sufficient data to look at outcomes in people who took four different kinds of diabetes medications — metformin, sulfonylureas, insulin, and DPP-4 inhibitors (such as Januvia, Galvus, Onglyza, and Tradjenta). The researchers found that compared with the overall death risk from COVID-19 in people with diabetes, those who took metformin were 31% less likely to die from the viral infection, and those who took a sulfonylurea were 20% less likely to die. Those who took insulin, though, were a stunning 120% more likely to die from COVID-19. People who took a DPP-4 inhibitor were 28% less likely to die from COVID-19, but this difference was (just barely) not statistically significant due to the smaller number of people who took a DPP-4 inhibitor.
The study authors noted that previous studies have also found that people who take metformin may be less likely to die from COVID-19, so the latest findings on the drug aren’t surprising. There is some evidence that metformin may have several anti-inflammatory effects in the body, which may explain the lower COVID-19 death risk. The potential connection between sulfonylureas and COVID-19 death risk is less clear. When it comes to insulin, the study authors wrote, other studies have shown that the drug may increase the risk for death in intensive care settings, possibly by promoting inflammation. While it is currently standard practice to administer insulin in hospital settings to reduce glucose levels when needed, “Our meta-analysis results suggest the need for careful assessment of the benefits and potential adverse effects of insulin therapy for patients with COVID-19,” the researchers concluded.
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