Understanding diabetes and blood sugar after COVID‑19

How does COVID-19 affect blood sugar regulation?

COVID-19 infection can affect how the body regulates blood sugar. During times of physical stress, blood sugar levels may temporarily increase as part of the response to illness.

Researchers have identified several reasons why COVID-19 may affect blood sugar regulation. The virus may directly affect the pancreas, which is the organ responsible for producing insulin. COVID-19 can also trigger an immune response that interferes with how the body uses insulin. In people treated with corticosteroids during severe COVID-19 illness, those medications can also contribute to temporary or lasting changes in blood sugar.

Changes in blood sugar levels can also occur after COVID-19, including persistent higher readings during recovery. Some people notice symptoms, while others do not experience any noticeable effects. Experiences vary widely, and there is no single pattern that applies to everyone.

Why might this happen? Some cases may be newly identified because people have more healthcare visits and lab testing after COVID‑19, and risk appears higher in those who had more severe illness. Research is still ongoing and more studies are needed to better understand examine the mechanisms that may explain this connection.

Many people recover from COVID-19 without developing diabetes or ongoing blood sugar concerns, however, for some, changes to blood sugar regulation can persist.

Temporary vs. ongoing blood sugar changes after COVID-19

After any significant illness, blood sugar can run higher for a period of time. For some people, those changes return to normal as recovery continues. For others, elevated blood sugar may persist and contribute to a new diagnosis, such as prediabetes or diabetes.

For people already living with diabetes, managing blood sugar (or glucose) may feel more challenging for a period after COVID-19 infection, and erratic glucose fluctuations have been documented in people with pre-existing Type 1 and Type 2 diabetes post-COVID.

Because blood sugar can fluctuate during recovery, monitoring patterns over time and discussing results with a healthcare provider can help clarify whether changes are temporary or ongoing. A single high reading might reflect short‑term stress on the body, while a pattern over weeks to months may suggest something that needs closer attention.

Who may be at higher risk of changes to blood sugar regulation after COVID-19?

Research points to a few groups that may be more likely to experience changes in blood sugar regulation after a COVID-19 infection:

• Those who experienced severe illness or hospitalization may be at higher risk of changes to blood sugar patterns.
• Those who are already managing other health conditions, including obesity, hypertension, cardiovascular conditions, and pre-existing metabolic disorders.
• Those with prediabetes or existing metabolic risk factors may be more at risk of metabolic changes following COVID‑19.
• Those already living with Type 1 or Type 2 diabetes.

Taking the COVID-19 risk assessment can help you understand whether you may be at increased risk for severe COVID-19, and support more informed next steps if you need care. Being higher risk does not necessarily mean blood sugar changes will occur, but understanding risk can help inform whether additional monitoring is recommended.

What symptoms or signs should I pay attention to?

Changes to blood sugar regulation don’t always cause clear or specific symptoms, especially early on. Some people may notice certain signals, such as:

• Feeling more fatigued than expected
• Increased thirst
• Needing to urinate more often
• Changes in appetite
• Blurred vision

Others may not notice symptoms at all, with changes identified only through routine blood tests.

It’s important to keep in mind that many of these signs can overlap with common post‑COVID-19 changes, such as ongoing tiredness, disrupted sleep, or changes in activity levels. This overlap can make symptoms hard to interpret on their own, and speaking to a healthcare provider can support your understanding.

How should blood sugar be monitored after COVID-19?

Monitoring depends on individual circumstances, including health history, symptoms, and whether changes are identified during routine care.

Monitoring may include blood tests during regular check-ups or follow-up appointments and can include home monitoring tools.

For people who have not previously been diagnosed with diabetes, a healthcare provider may recommend a fasting blood glucose test or an HbA1c (A1C) test, which reflects average blood sugar levels over the past 2–3 months. For those already managing diabetes, more frequent home monitoring or additional lab work may be recommended during and after COVID-19 recovery.

When and how often to check blood sugar levels is typically guided by individual needs and by your care team.

When should I talk to a doctor about diabetes concerns after COVID-19?

You do not need a diagnosis or severe symptoms to speak to a healthcare provider. It can be appropriate to book an appointment if:

• You develop new symptoms that could fit with high blood sugar, such as increased thirst or frequent urination
• You were hospitalized for COVID-19, since research suggests stronger links between severe illness and later diabetes diagnoses
• Higher readings or abnormal labs persist over several weeks
• Your A1C increases compared with your usual results, especially if the change is unexpected