Corticosteroids and Diabetes: How Steroids Cause High Blood Sugar and How to Manage It

When you're prescribed corticosteroids like prednisone or dexamethasone, you're usually told about the side effects: weight gain, trouble sleeping, mood swings. But one of the most dangerous and often overlooked risks is hyperglycemia-a sudden spike in blood sugar that can turn into full-blown steroid-induced diabetes. This isn’t just a minor inconvenience. It can land you in the hospital, prolong your recovery, or even be life-threatening if ignored.

Why Corticosteroids Raise Blood Sugar

Corticosteroids don’t just reduce inflammation-they mess with your body’s entire glucose system. They trigger a chain reaction that starts in your liver, moves to your muscles, and ends with your pancreas struggling to keep up.

In your liver, these drugs crank up glucose production by 35-40%. They activate enzymes that turn protein and fat into sugar, even when you haven’t eaten. At the same time, they make your muscles and fat cells ignore insulin. Normally, insulin tells your muscles to soak up glucose from the blood. But with corticosteroids, that signal gets blocked. Glucose uptake drops by about 30%, and sugar just piles up in your bloodstream.

Then there’s the pancreas. The cells that make insulin-beta cells-start to slow down. Corticosteroids reduce the expression of GLUT2 and glucokinase, the proteins that help beta cells sense blood sugar and respond with insulin. In some cases, insulin secretion drops by 20-35%. On top of that, the extra fat released from your fat tissue (thanks to corticosteroids) further poisons insulin signaling. This isn’t just insulin resistance. It’s insulin resistance plus insulin shortage. A double hit.

Who’s at Risk?

Not everyone on steroids gets high blood sugar. But some people are far more likely to. If you’re over 50, overweight (BMI 25 or higher), have a family history of diabetes, or had gestational diabetes, your risk jumps. A daily dose of 7.5 mg or more of prednisone increases your chance of hyperglycemia by more than three times. Dexamethasone? Even worse-it’s 6 to 8 times more likely to cause spikes than prednisone at the same anti-inflammatory dose.

The longer you’re on steroids, the higher your risk. Every week past the first two weeks, your chance of developing high blood sugar goes up by 12%. And if you’re on high doses for more than two weeks, you’re in the danger zone. About 20-50% of patients on high-dose corticosteroids develop hyperglycemia. In hospitals, that number hits 45-60%.

What the Symptoms Look Like (and Don’t Look Like)

You might think you’ll feel it. Thirst. Frequent urination. Fatigue. Blurred vision. And yes, those happen. About 72% of patients report peeing more often. 81% feel unusually tired. But here’s the catch: 40% of people show no symptoms at all. Their blood sugar climbs silently, and they only find out during a routine test.

The problem is, steroids cause other symptoms that look just like high blood sugar. Increased hunger? Common. Weight gain? Expected. Mood swings? Normal side effect. That’s why so many patients and even some doctors miss the diagnosis. One Reddit thread from the r/diabetes community had 147 comments-68% of people said no one warned them about this risk before starting steroids.

How Doctors Monitor and Diagnose It

If you’re on prednisone at 20 mg or more per day, or any equivalent high-dose steroid, your doctor should check your blood sugar at least twice a day. Fasting glucose above 140 mg/dL (7.8 mmol/L) or random glucose above 180 mg/dL (10.0 mmol/L) means it’s time to act.

In hospitals, they often use continuous glucose monitors (CGMs) for patients on IV steroids. In outpatient settings, fingerstick testing is still standard. The key is timing. Blood sugar doesn’t spike right after you take your steroid. It peaks 4 to 8 hours later. So if you take your steroid in the morning, check your sugar mid-afternoon-not right after breakfast.

How It’s Treated

Treatment isn’t one-size-fits-all. It depends on your steroid dose, your baseline health, and whether you had diabetes before.

If you’re new to diabetes and your blood sugar is only mildly high, lifestyle changes-cutting back on carbs, walking after meals-might be enough. But for most people on high-dose steroids, that’s not enough. Insulin is the go-to.

Basal insulin (long-acting) is usually started first. For every 10 mg increase in prednisone above 20 mg/day, insulin doses often need to go up by 20%. Rapid-acting insulin is added for meals, usually 1 unit for every 5-10 grams of carbs. This approach works because insulin directly counteracts the liver’s sugar overproduction and helps muscles take up glucose again.

Oral meds like metformin can help with insulin resistance, but they don’t fix the insulin shortage. Sulfonylureas (like glipizide) force the pancreas to make more insulin-but they’re risky. When steroids are tapered, your body starts making insulin again. If you’re still on a sulfonylurea, you can crash into dangerous low blood sugar. In fact, 37% of hypoglycemia events in steroid patients happen during tapering because of this.

What Happens When You Stop Steroids?

Good news: steroid-induced diabetes usually goes away. Once you stop the steroids, your liver slows down sugar production, your muscles start responding to insulin again, and your pancreas recovers. Blood sugar often normalizes in 3 to 5 days.

But here’s where things go wrong: many patients keep taking diabetes meds after the steroids are done. A 2023 study found that 63% of people kept using insulin or oral drugs long after their steroids were stopped-unnecessarily. That’s dangerous. It leads to low blood sugar, confusion, falls, and even seizures.

That’s why your doctor should recheck your blood sugar 48 hours after your last steroid dose. If it’s normal, you likely don’t need any more diabetes meds. But if it’s still high, you might have developed true type 2 diabetes. That requires a different, long-term plan.

What’s New in Management

New tools are emerging. The European Association for the Study of Diabetes launched a mobile app called STEROID-Glucose in early 2023. It takes your steroid dose and blood sugar reading, then recommends insulin adjustments in real time. In pilot studies, it cut hyperglycemic events by 32%.

The NIH is running a trial called GLUCO-STER, comparing insulin to GLP-1 receptor agonists (like semaglutide) for steroid-induced diabetes. Early results show GLP-1 drugs cause 28% fewer low blood sugar episodes. That’s promising-especially since they also help with weight loss, which is a big concern for steroid users.

Long-term, researchers are working on new steroids that fight inflammation without wrecking metabolism. Compound XG-201, in phase II trials, reduced hyperglycemia by 65% compared to regular prednisone at the same dose. That could be a game-changer for patients with autoimmune diseases who need long-term steroid therapy.

The Bigger Picture

Corticosteroids are used in 1-2% of the population every year. In people over 65, that number jumps to 8-10%. With rising use in cancer therapies like CAR-T (where 75-85% of patients develop hyperglycemia), this isn’t going away. The Endocrine Society predicts steroid-induced diabetes will become the third most common cause of secondary diabetes by 2030.

Hospitals are starting to pay attention. Medicare now ties quality scores to whether patients on steroids get proper glucose monitoring. The FDA requires hyperglycemia warnings on all corticosteroid labels since 2018. But in primary care? Only 65% of patients on long-term steroids get regular blood sugar checks.

This isn’t just a diabetes problem. It’s a systems problem. Too many patients slip through the cracks because no one’s looking for it. If you’re on corticosteroids, don’t wait for symptoms. Ask for your blood sugar to be checked. Know your numbers. And if you’re told you have steroid-induced diabetes, make sure you understand it’s likely temporary-and that stopping the meds doesn’t mean you need lifelong pills.