SARS-CoV-2 illness can push glucose higher during infection and in recovery, driven by stress hormones, inflammation, reduced activity, and steroid meds.
Getting sick can throw your blood sugar off, even when you’ve been steady for months. COVID-19 is no different. Some people see a mild bump for a few days. Others get a sharp rise that sticks around, shows up for the first time, or exposes prediabetes that was already there.
This article breaks down why glucose can climb with COVID-19, who tends to see bigger swings, what to track at home, and when to get urgent care. You’ll also get a practical checklist to keep readings steadier while your body fights an infection and resets afterward.
Why Blood Sugar Can Rise During COVID-19 Illness
Blood sugar is a moving target when your body is under strain. COVID-19 can create several “pushes” at once, and they often stack on top of each other.
Stress Hormones And The Glucose Surge
When you’re ill, your body releases stress hormones such as cortisol and adrenaline. Those hormones tell the liver to release more glucose into the blood. It’s a survival response that keeps fuel available for the brain and muscles.
If you already have diabetes, that hormone surge can outpace your usual medication plan. If you don’t have diabetes, your pancreas often keeps up. Still, some people see temporary high readings, then drift back to their baseline once they’re well.
Inflammation Can Increase Insulin Resistance
Inflammation can make your cells less responsive to insulin. When insulin resistance rises, the same meal or the same medication dose can lead to higher numbers than you’re used to seeing.
Fever, body aches, poor sleep, and dehydration can stack more pressure on glucose control. You may also eat less, eat irregularly, or rely on easy carbs because nothing else sounds good. That can swing readings in both directions.
Reduced Movement Changes Your Baseline
Even a few days of lower activity can raise your average glucose. Muscles act as a glucose sink, pulling sugar out of the blood during movement and in the hours after. When you’re stuck in bed or on the couch, that sink shrinks.
If you’re used to a daily walk keeping your numbers calm, losing that routine can show up fast on a meter or CGM.
Steroids Used For COVID-19 Can Spike Glucose
Some COVID-19 cases are treated with corticosteroids such as dexamethasone, mainly for people with low oxygen or more severe illness. Steroids can raise blood sugar by increasing insulin resistance and nudging the liver to release more glucose.
In the hospital, teams often add insulin, adjust doses, or increase monitoring for people receiving steroids. The Endocrine Society inpatient hyperglycemia resources outline how clinicians manage high glucose during hospitalization, including situations involving glucocorticoids.
COVID-19 And High Blood Sugar With Recovery: What Drives The Spike
Many people feel “off” for weeks after COVID-19. Glucose can follow the same pattern. You might see higher fasting readings, higher post-meal spikes, or more variability day to day.
Post-Illness Changes That Can Linger
Recovery often comes with lower activity, disrupted sleep, and appetite changes. If you lost muscle while sick, your body may handle carbs differently for a while. If you gained weight during recovery, insulin resistance can rise.
Medication changes can also matter. Some people pause diabetes meds during illness because they can’t keep food down. Others leave the hospital on a new insulin plan. It can take time to find the “right” doses again.
Newly Noticed Prediabetes Or Diabetes
COVID-19 doesn’t “give” everyone diabetes, yet it can expose a problem that was already brewing. Many adults live with prediabetes and don’t know it. An infection can push glucose high enough to get tested, then the underlying trend becomes visible.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) summarizes what scientists are learning about COVID-19 and diabetes, including patterns of new diabetes diagnoses after infection and how ongoing NIH programs are tracking outcomes. See NIDDK’s overview on research linking COVID-19 and diabetes for a current, clinician-reviewed snapshot.
When Higher Readings Signal A Bigger Problem
A few higher readings during recovery can be normal. Still, persistent highs deserve attention. If your fasting glucose stays elevated for weeks, or your post-meal spikes are larger than your usual range, it’s a cue to check in with a clinician and ask if you need labs such as A1C.
If you have diabetes, higher readings during recovery can raise the risk of dehydration and ketones. If you don’t have diabetes, repeated highs can be the first clue that you need follow-up testing.
Who Tends To See Bigger Glucose Swings
COVID-19 can raise glucose in many people, yet some groups run into larger spikes or longer-lasting changes.
- People with type 1 diabetes: Illness can raise insulin needs quickly, and ketones can build faster when insulin is short.
- People with type 2 diabetes: Insulin resistance can rise with infection, inactivity, and steroids, making usual doses feel “weak.”
- People with prediabetes: An infection can push glucose into the diabetes range, even if it later settles.
- People treated with steroids: Dexamethasone and similar meds can drive high post-meal readings, often later in the day.
- Older adults and people with more severe illness: Longer illness, less movement, and more medications can raise variability.
Also, diabetes itself can raise the risk of severe COVID-19 outcomes. The CDC discusses this relationship and why diabetes management matters during COVID-19 in its reporting and education pages, including CDC’s diabetes and COVID-19 overview.
What To Track At Home When You’re Sick
If you already monitor glucose, illness is the moment to watch trends more closely. If you don’t normally check, your clinician may still suggest short-term checks during COVID-19, mainly if you have prediabetes, take steroids, or notice symptoms of high glucose.
Numbers That Often Trigger Action
Targets vary by person, meds, age, pregnancy status, and other health factors. Your care plan is the first stop. Still, these are common action points many clinicians use during illness:
- Repeated readings above 240 mg/dL: Many sick-day plans recommend checking ketones after two readings above this level.
- Unexpected lows: Skipped meals, vomiting, diarrhea, or reduced meds can drop glucose quickly.
- Fast-rising trend lines: A rapid climb over a few hours can signal dehydration, infection progression, or missed insulin.
The American Diabetes Association’s sick-day guidance includes practical thresholds and steps, including when to check ketones. See ADA “If You Get Sick, Know What to Do” for a clear checklist you can adapt with your clinician.
Ketones And Why They Matter
Ketones can build when the body can’t use glucose well due to low insulin. This can happen in type 1 diabetes, and it can also happen in type 2 diabetes during severe illness, steroid treatment, or missed insulin. Moderate to large ketones are a red flag that needs medical advice right away.
If you feel nauseated, have belly pain, breathe rapidly, or can’t keep fluids down, treat it as urgent, even if you aren’t sure what the meter means.
Common COVID-19 Situations That Shift Glucose
The same infection can affect two people in different ways. The patterns below can help you guess what’s driving your readings so you can respond faster.
Dehydration And “Sticky” High Readings
Fever and sweating can dry you out. High blood sugar can also pull fluid into the urine. That combo can make readings climb and stay high. Sipping fluids through the day can steady things, even when you don’t feel like eating much.
Over-The-Counter Meds And Hidden Carbs
Cough syrups, throat lozenges, and some liquid cold meds can contain sugar. Read labels. If you use electrolyte drinks, check the carb count per serving. If you’re using a CGM, you may spot spikes that line up with these products.
Appetite Loss, Then Catch-Up Eating
Many people eat lightly for a day or two, then get hit with sudden hunger once symptoms ease. That swing can create a “low then high” pattern. Planning small, steady meals can smooth the rebound.
Table: Triggers, What You May See, And What To Do First
This table gathers common causes of higher glucose during COVID-19 and the first moves people often use at home. Use it alongside your own care plan.
| Trigger During COVID-19 | What You May Notice | First Moves That Often Work |
|---|---|---|
| Fever or acute infection stress | Higher fasting and all-day readings | Check more often; hydrate; follow sick-day insulin or med plan |
| Corticosteroids (dexamethasone, prednisone) | Big post-meal spikes, often later in the day | Ask about temporary dose changes; watch afternoon/evening trends |
| Less movement | Higher baseline, slower drop after meals | Gentle movement when safe; short walks at home if breathing allows |
| Dehydration | “Stubborn” highs that don’t budge | Fluids in small sips; recheck after hydration; watch urine color |
| Skipped meals or vomiting | Lows, then rebounds, then highs | Carb-containing fluids; adjust meds with clinician guidance |
| High-carb comfort foods | Large post-meal spikes | Smaller portions; add protein/fat when tolerated; spread carbs out |
| Sleep loss | Higher morning readings | Nap when possible; steady meal timing; limit late-night snacking |
| New glucose meter or CGM changes | Numbers that don’t match symptoms | Confirm with a finger-stick; check strips and device settings |
| Missed insulin or meds | Rapid rise over hours | Use your correction plan; watch ketones if readings stay high |
When To Get Medical Care Right Away
COVID-19 can become serious fast, and high glucose can add extra strain. Don’t wait it out if you see warning signs that point to dehydration, ketones, or breathing trouble.
Urgent Red Flags
- Moderate to large ketones, or ketones plus high glucose
- Vomiting that lasts more than a few hours, or you can’t keep fluids down
- Severe weakness, confusion, or fainting
- Rapid breathing, chest pain, or low oxygen readings if you use a pulse oximeter
- Blood sugar that stays very high despite following your correction plan
If you have a known sick-day plan, follow it. If you don’t, call a clinician or an urgent care line and report your symptoms, glucose trend, and ketone results if you checked them.
Does COVID-19 Raise Blood Sugar? Steps To Keep Readings Steadier
If your glucose is running higher than usual, your goal is steadiness, hydration, and early action. You’re not chasing perfect numbers while you’re sick. You’re trying to avoid extremes and spot danger signs early.
Step 1: Increase Check Frequency For A Short Window
If you use finger-sticks, many people check every 4 hours while awake during illness, then adjust based on trends. CGM users can watch trend arrows and confirm with finger-sticks when readings don’t fit how they feel.
Write down readings, meds taken, meals, and symptoms. A short log makes it easier to spot what changed when you call a clinician.
Step 2: Keep Fluids Going
When glucose is high, hydration matters. Choose water, broth, tea, or sugar-free electrolyte drinks. If you can’t eat and you’re at risk for lows, use carb-containing fluids in measured amounts, then recheck.
Step 3: Don’t Stop Insulin Without A Plan
For many people with type 1 diabetes, stopping insulin during illness can lead to ketones quickly. For type 2 diabetes, medication changes depend on what you take, your kidney function, and how well you can eat and drink.
If you’re unsure, call a clinician and ask what to hold, what to continue, and what to adjust for the next 24–48 hours.
Step 4: Watch Steroid Timing
If you’re on a steroid, your glucose rise may track the timing of each dose. Many people see the biggest spikes after lunch and dinner. That pattern can guide when you check and when you discuss temporary insulin changes with your care team.
Step 5: Use Small Meals With Protein When You Can
When appetite is low, large meals can backfire. Small, repeatable choices can be easier: soup with beans, eggs with toast, yogurt, cottage cheese, or a smoothie with measured carbs and added protein.
If you can tolerate food, pairing carbs with protein and fat can blunt spikes. If you can’t tolerate food, focus on fluids first.
Table: Practical Sick-Day Checklist For Glucose During COVID-19
This checklist is designed for quick scanning when you’re tired and foggy. Use it as a “do this next” list, not as a replacement for your clinician’s plan.
| What To Prepare | What To Do During Illness | When To Escalate |
|---|---|---|
| Meter/CGM supplies and extra batteries | Check more often for 2–5 days, then taper as you improve | Numbers stay high and rising despite correction plan |
| Ketone strips (urine or blood) | Check ketones after repeated high readings or if you feel nauseated | Moderate/large ketones, or ketones plus vomiting |
| Fluids: water, broth, electrolyte drinks | Sip through the day; aim for pale yellow urine | Dizziness, fainting, dry mouth, no urination |
| Simple carbs for lows (glucose tabs, juice) | Treat lows promptly; recheck in 15 minutes | Repeated lows or confusion |
| Medication list with doses | Follow sick-day med plan; log what you take | Can’t keep meds down or can’t eat for long stretches |
| Quick meals you can tolerate | Small meals spaced out; add protein when possible | Ongoing vomiting or signs of dehydration |
| Clinician phone number and pharmacy info | Call early if trends look off; share your log | Breathing trouble, chest pain, severe weakness |
After You Recover: How Long Should You Watch Glucose?
For many people, readings drift back toward baseline within days to a few weeks. If you had steroid treatment, your glucose may settle as the steroid tapers off, then return closer to your usual pattern.
If you had COVID-19 and saw new or persistent highs, it’s reasonable to track for a few weeks after symptoms fade. If the trend stays elevated, ask for follow-up testing. A1C can show whether the rise is a short spike or part of a longer pattern.
Signs You May Need A Medication Tune-Up
- Fasting readings stay higher than your prior baseline for multiple weeks
- Post-meal spikes are larger than your prior pattern with similar meals
- Your usual activity level returns, yet glucose stays elevated
- You notice thirst, frequent urination, blurry vision, or unusual fatigue
If you’re already diagnosed with diabetes, a temporary change in insulin or other meds is common after illness. If you weren’t diagnosed before, persistent highs deserve a workup rather than guesswork.
Prevention Moves That Pay Off For Glucose Stability
You can’t control every variable in an infection, yet a few choices reduce the odds of extreme glucose swings.
Stay Current With Vaccination And Routine Care
Lowering the chance of severe COVID-19 often reduces the chance of needing steroids, being bedridden for long stretches, or dealing with long recovery. If you have diabetes, keep regular checkups and refill cycles steady so you don’t run short during illness.
Build A Two-Day “Sick Shelf”
Keep a small stash of easy foods and drinks you can tolerate when you feel lousy. Include options that cover both high and low glucose situations. Keep ketone strips and spare supplies in the same spot so you’re not hunting around when you’re tired.
Know Your Personal “Call Now” Triggers
Write down your own action points: the glucose level where you check ketones, the point where you call a clinician, and the symptoms that mean urgent care. If you already use ADA sick-day steps, tailor them to your meds and your health history.
COVID-19 can raise blood sugar through multiple routes at once. If you plan for it, track early, and act fast when trends shift, you can lower the chance that a short illness turns into a longer glucose problem.
References & Sources
- Endocrine Society.“Inpatient Hyperglycemia Guideline Resources.”Clinical guidance on managing hyperglycemia in hospitalized adults, including higher risk with glucocorticoid therapy.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).“Research on COVID-19 and Diabetes Sets the Stage for Care.”Overview of findings and ongoing NIH programs tracking links between COVID-19 and diabetes outcomes.
- Centers for Disease Control and Prevention (CDC).“Diabetes and COVID-19.”Public health summary on diabetes and COVID-19, reinforcing why diabetes management matters during the pandemic.
- American Diabetes Association (ADA).“If You Get Sick, Know What to Do.”Sick-day steps for diabetes, including guidance on glucose checks, ketones, hydration, and when to seek care.