Corticosteroid-Induced Hyperglycemia and Diabetes: How to Monitor and Manage It

When someone starts taking corticosteroids-whether for asthma, rheumatoid arthritis, or after an organ transplant-they’re often told about side effects like weight gain or trouble sleeping. But one of the most dangerous, and often overlooked, effects is a sudden spike in blood sugar. This isn’t just a minor inconvenience. It’s corticosteroid-induced hyperglycemia, a condition that can turn a person without diabetes into someone with dangerously high glucose levels in just days.

Why Corticosteroids Raise Blood Sugar

Corticosteroids like prednisone, dexamethasone, and hydrocortisone don’t just reduce inflammation. They also mess with how your body uses sugar. These drugs trigger a triple attack on your metabolism: they make your liver pump out more glucose, block your muscles from absorbing it, and silence your pancreas from making enough insulin.

In the liver, corticosteroids boost two key enzymes-phosphoenolpyruvate carboxykinase and glucose-6-phosphatase-that crank up glucose production by nearly 38%. At the same time, they interfere with GLUT4 transporters in muscle cells, cutting glucose uptake by over 40%. Meanwhile, insulin-producing beta cells in the pancreas respond by reducing their output by more than 20%, especially when exposed to high doses like 75 mg of prednisolone. The result? Blood sugar climbs fast, often within hours of the first dose.

This isn’t the same as type 2 diabetes. In type 2, insulin resistance builds slowly over years. With steroid-induced hyperglycemia, it hits like a wave. And it follows a pattern: blood sugar spikes in the morning-right when the steroid peaks-and drops later in the day. Many doctors miss this, treating it like regular diabetes and giving the same insulin doses all day. That’s a mistake.

Who’s at Highest Risk?

Not everyone on steroids develops high blood sugar. But certain people are far more likely to. If you have a BMI over 30, your risk jumps 3.2 times compared to someone with a normal weight. If you already have prediabetes or impaired glucose tolerance, your risk is nearly five times higher. Older adults, people with a family history of diabetes, and those on high-dose or long-term steroids are also at greater risk.

The dose matters too. Patients taking more than 20 mg of prednisone (or its equivalent) daily are far more likely to develop hyperglycemia than those on low doses. Even short courses-like a five-day burst for a flare-up-can trigger spikes in vulnerable people. And it’s not just hospital patients. People taking oral steroids at home are just as at risk, especially if they’re not monitored.

How to Monitor Blood Sugar Correctly

Waiting for symptoms like excessive thirst or fatigue is too late. By then, blood sugar may already be dangerously high. The standard advice from the NIH and the Endocrine Society is clear: start checking glucose within 24 hours of starting corticosteroid therapy.

For high-risk patients, check fasting glucose and post-meal glucose at least twice a day. Don’t just check in the morning. Check after lunch and dinner too. Why? Because steroid-induced hyperglycemia doesn’t follow a steady curve. It’s jagged. Morning levels may hit 200 mg/dL or higher, while evening levels might drop to 120 mg/dL. If you only test fasting glucose, you’ll miss the afternoon spikes-and the nighttime lows that can happen when steroids are tapered.

Continuous glucose monitors (CGMs) are becoming essential tools. A 2021 study found that 68% of patients with steroid-induced hyperglycemia had unrecognized high or low glucose events that fingersticks completely missed. CGMs catch nocturnal hypoglycemia during steroid tapering-a dangerous but common issue that’s often blamed on “patient error” when it’s actually a direct effect of the drug wearing off.

When to Start Insulin

Many providers still use sliding scale insulin for steroid hyperglycemia. That’s outdated. Sliding scale reacts to high numbers after they happen. It doesn’t prevent them. Basal-bolus insulin-combining a long-acting insulin (like glargine or detemir) with rapid-acting insulin before meals-is far more effective. A 2022 JAMA trial showed it improves glucose control by 35% compared to sliding scale.

For patients with pre-existing diabetes, expect to increase insulin doses by 20% to 50%. For those without prior diabetes, insulin may be needed if glucose levels stay above 180 mg/dL on two consecutive readings. Don’t wait for 250 or 300. Start early. The goal isn’t perfection-it’s preventing complications like hyperosmolar hyperglycemic state (HHS), which occurs in nearly 5% of severe cases.

Timing matters. If the steroid is given once daily in the morning, give the largest insulin dose at breakfast. Reduce afternoon doses. If the steroid is given twice daily, split the insulin accordingly. Many treatment errors happen because insulin is given like it’s for regular diabetes-not for the steroid’s clock.

What Happens When Steroids Are Stopped?

Stopping steroids doesn’t mean blood sugar normalizes overnight. Insulin resistance can linger for 16 to 24 hours after the last dose. That’s why monitoring should continue even on non-steroid days. And during tapering, the risk of hypoglycemia spikes. As the steroid effect fades, insulin sensitivity returns-but if insulin doses aren’t lowered, blood sugar can crash.

Patients often describe this as a “rollercoaster.” One day they’re fine. The next, they’re dizzy, sweating, confused. That’s not anxiety. It’s low blood sugar. In a 2023 survey of 1,243 patients, nearly 70% reported unexpected hypoglycemia during steroid tapering. Many didn’t know to reduce their insulin. Clinicians didn’t warn them.

Why So Many Hospitals Get It Wrong

Despite clear guidelines, most hospitals don’t have standardized protocols. A 2023 study found that only 58% of non-critical care units had any formal plan for managing steroid-induced hyperglycemia. In those without protocols, patients waited 42% longer to get treatment. That delay increases infection risk, prolongs hospital stays, and raises costs.

Even among doctors, knowledge gaps are wide. Only 44% of non-endocrinology physicians correctly identified the morning-dominant glucose pattern. Many assume high blood sugar means the patient “has diabetes,” not that it’s a drug side effect. That leads to misdiagnosis, unnecessary long-term medications, and missed opportunities to reverse the condition.

The Mayo Clinic’s Steroid Diabetes Protocol fixed this. They mandated point-of-care glucose testing within four hours of the first steroid dose. If two readings were above 180 mg/dL, insulin was started automatically using a simple algorithm. Within two years, complications dropped by over 50%.

The Bigger Picture: Costs, Trends, and Future Solutions

Every year in the U.S., over 2 million hospital admissions involve corticosteroid therapy. Nearly half of those patients develop hyperglycemia. That’s a massive burden on the healthcare system. But good management pays off. Proper care reduces hospital stays by nearly two days per patient-saving over $2,300 per admission.

Rheumatology, oncology, and pulmonology are the top three specialties prescribing high-dose steroids. As steroid use grows-especially for autoimmune and inflammatory conditions-so will steroid-induced diabetes. The FDA now requires all systemic corticosteroid labels to include hyperglycemia warnings. That’s progress.

The future is moving toward precision medicine. The NIH’s GLUCO-STER trial is testing a machine learning tool that predicts who’ll develop hyperglycemia based on BMI, HbA1c, steroid dose, and even genetic markers like GR-1B polymorphisms. Early results show 84% accuracy. That could mean preemptive insulin for high-risk patients before their sugar even rises.

Meanwhile, researchers are developing new drugs-tissue-selective glucocorticoid receptor modulators-that fight inflammation without wrecking metabolism. Three are already in Phase II trials, cutting hyperglycemia risk by over 60% compared to standard steroids. These could be game-changers.

What You Can Do Now

If you’re prescribed corticosteroids:

• Ask your doctor: “Will this affect my blood sugar?”
• Request glucose monitoring starting the first day.
• Use a CGM if possible-it catches what fingersticks miss.
• Don’t assume your insulin dose stays the same. Adjust it as steroids are tapered.
• Watch for dizziness, sweating, or confusion during tapering-these are signs of low blood sugar.

If you’re a clinician:

• Start glucose checks within 24 hours of steroid initiation.
• Use basal-bolus insulin, not sliding scale.
• Adjust insulin timing to match steroid dosing-morning steroids need morning insulin.
• Don’t stop monitoring when steroids are reduced.
• Create a simple protocol in your unit. It saves lives.

Corticosteroids save lives. But they also create new ones at risk. The key isn’t avoiding them-it’s managing their side effects with the same precision we use for the disease they treat.