Why Do Steroids Increase Blood Sugar? Prednisolone, Dexamethasone and Diabetes

By Dr. Moxit Shah, DM Endocrinology | Vishuddha Diabetes, Thyroid, Weight Loss Clinic, Ahmedabad

Can steroids increase blood sugar? Yes. Steroid medicines can raise glucose even in people without diagnosed diabetes. The rise may be especially noticeable after lunch or dinner, while fasting sugar looks deceptively normal.

Why Can Steroid Medicines Raise Blood Sugar?

Corticosteroids such as prednisolone, methylprednisolone, dexamethasone and hydrocortisone are used for asthma flare-ups, autoimmune disorders, severe allergies and other inflammatory conditions. They can also increase blood glucose. Steroids stimulate glucose production by the liver and make muscle and fat cells less responsive to insulin. In people with limited insulin reserve, this can uncover previously unrecognized diabetes or worsen existing diabetes. The effect depends on steroid type, dose, timing, duration and the person’s metabolic health.

Who Is More Likely to Develop Steroid-Induced High Blood Sugar?

People with type 2 diabetes, prediabetes, a previous history of gestational diabetes, higher body weight, older age or a family history of diabetes are at increased risk. However, steroid-induced hyperglycaemia can occur even in someone without known diabetes. Higher doses and longer courses tend to increase risk, although clinically important elevations can occur during shorter courses too.

Why Can Fasting Sugar Be Normal but Afternoon Sugar High?

This is one of the most important patterns to recognize. When an intermediate-acting steroid such as prednisolone is taken in the morning, glucose may rise predominantly after lunch and during the afternoon or evening. The next morning’s fasting glucose can be relatively normal. A fasting test alone may therefore miss steroid-related hyperglycaemia. Long-acting dexamethasone or multiple daily steroid doses may cause more sustained elevations throughout the day and night.

What Are the Symptoms?

Many patients have no symptoms, especially early on. Others notice increased thirst, frequent urination, fatigue, blurred vision or recurrent infections. Very high glucose may lead to dehydration, vomiting, confusion or other acute illness. Seek urgent medical care for severe symptoms, persistent very high readings or signs of diabetic ketoacidosis or hyperosmolar hyperglycaemic state.

Which Blood Sugar Tests Are Useful?

For people at risk, checking capillary blood glucose around lunch or dinner, or two hours after meals, may detect rises that a fasting test misses. Monitoring frequency should match clinical risk, the steroid regimen and whether the person already uses diabetes medicines. An HbA1c test helps identify pre-existing chronic hyperglycaemia but may not reliably reflect a newly started steroid course because HbA1c represents average glucose over preceding weeks to months. A continuous glucose monitor may be useful in selected patients.

What Blood Sugar Levels Require Attention?

Treatment thresholds depend on the setting and the individual. In many outpatient steroid-monitoring protocols, repeated glucose readings around or above 200–216 mg/dL (11.1–12 mmol/L) warrant prompt clinical review, especially if symptoms occur. These figures are not universal treatment targets. People with diabetes should follow individualized targets set by their treating clinician. A single reading should be interpreted in the context of symptoms, meals, steroid timing and other medicines.

Can Steroid-Induced Diabetes Be Temporary?

Sometimes. Glucose levels often improve when the steroid dose is reduced or stopped, but not always. Steroids may reveal underlying type 2 diabetes that persists afterward. Follow-up glucose testing is important after treatment ends. Patients should not assume that their diabetes has disappeared simply because symptoms improve.

How Is Steroid-Related Hyperglycaemia Treated?

The first step is to assess the steroid schedule, glucose pattern and clinical severity. In mild cases, meal planning, activity where appropriate and closer monitoring may be sufficient. Some people require adjustment of existing diabetes tablets or injectable treatment. Insulin is often needed for marked hyperglycaemia, during hospital illness or when steroid doses are high. Clinicians may choose an insulin regimen that matches the steroid’s time course; for example, morning NPH insulin can sometimes match the afternoon glucose rise caused by morning prednisolone. Other patients need basal-bolus or different regimens. There is no safe one-size-fits-all dose.

What Happens When Steroids Are Reduced or Stopped?

This is a particularly important safety point: insulin and other glucose-lowering treatment may need to be reduced as steroid doses fall. Otherwise, hypoglycaemia can occur. Never independently stop prescribed steroids, especially after prolonged use, because abrupt withdrawal can be dangerous. Steroid tapering and diabetes medicine changes should be coordinated with the prescribing clinician.

Practical Indian Meal and Monitoring Tips

Continue balanced meals rather than skipping food to force glucose readings down. Choose appropriate portions of roti, rice or millets; add dal, vegetables and protein; avoid sugary beverages; and spread carbohydrates consistently across meals. A short walk after meals may help when medically appropriate. During illness, dehydration or reduced food intake, seek individualized advice. Keep a log showing steroid name, dose, time taken, meals and glucose readings—this makes treatment adjustments safer.

When Should You Contact a Doctor?

Contact your treating team if readings repeatedly exceed your agreed targets, if glucose is persistently around or above 200–216 mg/dL, or if thirst, frequent urination or blurred vision develops. Seek urgent assessment for vomiting, severe weakness, rapid breathing, confusion, marked dehydration or very high readings. Patients using insulin should have a clear plan for hypoglycaemia and sick days.

Frequently Asked Questions

Can prednisolone increase blood sugar even if I do not have diabetes?

Yes. Prednisolone can cause temporary hyperglycaemia or uncover diabetes in susceptible people.

Why is my fasting sugar normal after taking steroids?

Morning prednisolone often causes its largest glucose rise later in the day, so afternoon or post-meal testing may be more informative.

Does dexamethasone raise blood sugar longer?

It can. Dexamethasone is longer acting and may cause more sustained glucose elevation.

Should I stop steroids if my sugar is high?

No. Speak with the prescribing doctor. Abruptly stopping steroids can be unsafe.

Will I need insulin permanently?

Not necessarily. Treatment needs may decrease as steroids are reduced, but some people have persistent diabetes.

Can HbA1c diagnose new steroid-induced hyperglycaemia?

HbA1c can help assess previous glycaemia, but it may miss a recent glucose rise during a short steroid course.

Related Diabetes Guides

Read more about high HbA1c despite normal fasting glucose, post-meal blood sugar levels, diabetes sick-day rules and CGM time in range.

Consult a Diabetes Specialist in Ahmedabad

If your blood sugar has risen after starting steroids, consult Dr. Moxit Shah, DM Endocrinology at Vishuddha Diabetes, Thyroid, Weight Loss Clinic, 104–105, Elite Magnum, Bhuyangdev Cross Road, Ghatlodiya, Ahmedabad – 380061, Gujarat, India. Appointments: +91 99799 92797. Bring your steroid prescription and recent glucose readings.

Medical References and Disclaimer

1. American Diabetes Association. Standards of Care in Diabetes—2026: Management of Diabetes in the Hospital.
2. Joint British Diabetes Societies for Inpatient Care. Management of Hyperglycaemia and Steroid (Glucocorticoid) Therapy: Clinical Guidance.
3. Endocrine Society. Management of Hyperglycemia in Hospitalized Adult Patients in Non-Critical Care Settings: Clinical Practice Guideline, 2022.

Educational information only. Steroids and diabetes medicines must be adjusted under medical supervision. Do not stop corticosteroids abruptly.