How Steroids Affect Blood Sugar and What to Do

Corticosteroids, the anti-inflammatory drugs prescribed for conditions ranging from asthma to autoimmune disease, raise blood sugar in virtually everyone who takes them. They do so through a combination of increased glucose production in the liver and reduced ability of your muscles and fat tissue to absorb that glucose. For people without diabetes, the rise may be mild and temporary. For those who already have diabetes or are at risk for it, steroid-induced hyperglycemia can become severe enough to require medication changes and close monitoring. The good news is that the pattern of blood sugar disruption is fairly predictable, and there are concrete strategies to manage it.

How Steroids Push Blood Sugar Up

Corticosteroids are synthetic versions of cortisol, the hormone your body releases during stress. One of cortisol’s primary jobs is to keep blood sugar available when your body thinks it needs fuel, and synthetic steroids amplify that signal well beyond what’s useful. The effect plays out on several fronts simultaneously.

In the liver, steroids ramp up a process called gluconeogenesis, where the organ manufactures new glucose from amino acids, glycerol, and other raw materials. To supply those raw materials, steroids trigger the breakdown of fat in adipose tissue and protein in skeletal muscle, funneling substrates into the liver’s glucose-making machinery.¹ At the same time, steroids interfere with insulin’s ability to shuttle glucose into muscles and fat cells. In muscle tissue, the insulin signaling chain is disrupted at multiple steps, reducing glucose uptake and glycogen storage.² The net result is a double hit: your liver floods the bloodstream with glucose while your muscles struggle to absorb it.³

Steroids also act directly on the insulin-producing beta cells of the pancreas. Short-term exposure triggers a compensatory response where beta cells boost alternative signaling pathways to maintain insulin output despite impaired calcium-channel function.⁴ But this workaround has limits. With longer or higher-dose exposure, beta cells begin to die off and insulin secretion drops. Both rat and human beta cells show increased cell death and reduced glucose-stimulated insulin release after sustained glucocorticoid treatment.⁵ ⁶ So your body simultaneously makes too much glucose, can’t use it properly, and eventually loses some of its capacity to produce the insulin needed to bring levels back down.

The Afternoon-to-Midnight Pattern

One of the most practically useful things to know about steroid-induced blood sugar rises is their timing. If you take a morning dose of a common steroid like prednisone, your fasting blood sugar the next morning may look reassuringly normal. The trouble shows up later in the day. Research tracking 24-hour glucose profiles in people taking a moderate dose of prednisone found that hyperglycemia was concentrated from midday to midnight, driven first by suppressed insulin secretion and then by reduced insulin action, with both effects dissipating overnight.⁷

This pattern matters because it can fool standard monitoring. If your doctor only checks a fasting glucose or your morning fingerstick looks fine, the large afternoon and evening spikes can go completely undetected. People on steroids who want to understand what is actually happening to their blood sugar should test before and after lunch and dinner, not just first thing in the morning. The mismatch between morning results and daytime reality is one of the most common sources of missed steroid-induced hyperglycemia.

Not Just Pills and Infusions

Many people assume that only high-dose oral or intravenous steroids affect blood sugar. That isn’t the case. Steroid injections into joints, a routine treatment for arthritis and tendon problems, also push glucose up. A systematic review of blood glucose responses after intra-articular steroid injections in patients with diabetes found that every study showed a rise, with peak values reaching as high as 500 mg/dL in some cases.⁸ The peak didn’t happen right away, either. In many patients, the worst hyperglycemia appeared within one to three days after the injection.

A study of musculoskeletal steroid injections confirmed that blood glucose was significantly elevated one day after injection compared to baseline, though it tended to come back down by the second day.⁹ Interestingly, that study found no significant differences based on injection site or steroid dose, suggesting that even a single low-dose joint injection can produce a meaningful glucose spike if you have diabetes. If you’re getting a cortisone shot in your knee or shoulder, plan to check your blood sugar more frequently for the next two to three days.

Inhaled corticosteroids, the kind used daily for asthma and COPD, generally have a smaller systemic effect. But at high doses and over long periods, even inhaled steroids show a positive correlation with higher blood glucose levels, particularly in children on long-term treatment.¹⁰ The risk goes up with both increasing dose and longer duration of use.

Who Is Most Vulnerable

Steroid-induced hyperglycemia can affect anyone, but the severity varies enormously. People with pre-existing type 2 diabetes are the most obviously at risk. Their insulin production and sensitivity are already compromised, and adding a steroid can tip glucose control from manageable to chaotic. An important point often overlooked in clinical practice is whether the patient had undiagnosed or overlooked diabetes before the steroid was prescribed. Checking HbA1c at the start of steroid therapy can reveal pre-existing glucose problems that would otherwise be blamed entirely on the medication.¹¹ This distinction matters because pre-existing diabetes won’t resolve when the steroid stops, and it usually requires more aggressive insulin management.

People without a diabetes diagnosis are not immune. A portion of patients started on steroids develop new-onset hyperglycemia, sometimes called steroid-induced diabetes. The risk is higher with higher doses and longer courses, and it tends to affect people who already have risk factors like obesity, a family history of diabetes, or a prior history of gestational diabetes. Since the advent of glucocorticoid therapy in the 1940s, hyperglycemia has been recognized as one of the most common side effects, frequently leading to hospital admissions, prolonged stays, and increased infection risk.

Why Uncontrolled Blood Sugar on Steroids Is Dangerous

Steroid-induced hyperglycemia isn’t just an inconvenient lab value. It carries real clinical consequences. Among patients with newly diagnosed multiple myeloma undergoing steroid-containing chemotherapy, those who developed overt hyperglycemia (glucose above 200 mg/dL) had a dramatically higher risk of serious infections. After adjusting for other factors, overt hyperglycemia was the strongest independent predictor of severe infection, with roughly an eightfold increase in risk.¹²

The pattern holds across other conditions. A systematic review of glioblastoma patients found that both transient and persistent steroid-induced hyperglycemia were associated with worse functional recovery, higher infection rates, longer hospital stays, and reduced overall survival.¹³ Some evidence suggests that hyperglycemia itself may partly explain the poor outcomes often attributed to steroid use, making glucose management a potentially modifiable factor in patient recovery. Despite this, formal treatment guidelines remain incomplete, and management often comes down to individual clinician judgment.

Monitoring That Actually Catches the Problem

Because steroid-induced blood sugar spikes follow an afternoon-to-evening pattern when a morning dose is taken, standard fasting glucose checks miss much of the problem. If you’re using a fingerstick meter, the most informative readings are typically before lunch, two hours after lunch, and before dinner. Those windows line up with the period when prednisone-type steroids have their largest glycemic effect.

Continuous glucose monitors offer a clearer picture because they capture every swing around the clock. Research using CGM in diabetic patients receiving steroid injections found that the first 48 to 72 hours after a steroid dose is the most clinically revealing window for identifying blood sugar patterns.¹⁴ If you already wear a CGM for diabetes management, pay close attention to trend data in the days after starting or increasing a steroid. If you don’t normally use one, wearing a CGM during a steroid course could help you and your doctor make more targeted treatment decisions.

Treatment Strategies

The choice of treatment for steroid-induced hyperglycemia depends on how severe the glucose elevation is, whether you already have diabetes, and how long you’ll be on the steroid.

Oral Medications for Milder Cases

For people without pre-existing diabetes who develop mild hyperglycemia on a moderate steroid dose, oral glucose-lowering drugs can sometimes be enough. All major classes of oral diabetes medications have been used in this setting.¹⁵ However, insulin remains the most studied and most commonly recommended medication for more severe cases, for people who already have diabetes, and for those on prolonged steroid courses.

Matching Insulin to the Blood Sugar Pattern

The afternoon peak pattern of steroid-induced hyperglycemia has practical implications for insulin selection. An intermediate-acting insulin like NPH, given in the morning around the same time as the steroid, provides a wave of insulin coverage that peaks in the afternoon and wanes by nighttime, which roughly mirrors the glucose trajectory caused by a morning prednisone dose. A randomized trial of hospitalized diabetic patients on corticosteroids found that an NPH-based protocol lowered average glucose significantly compared to usual care, with the biggest improvements at fasting and before lunch.¹⁶ Before-dinner and bedtime glucose values, however, were not significantly different between groups, reflecting the fact that the steroid effect was beginning to fade by evening.

A comparison of NPH and the long-acting insulin glargine as basal therapy in hospitalized patients on prednisone found similar overall glycemic control between the two approaches, with comparable fasting blood glucose, average daily glucose, and rates of hypoglycemia.¹⁷ The implication is that either can work, though NPH’s pharmacological profile is a more intuitive match for the once-daily-morning-steroid scenario.

For patients with pre-existing diabetes who are already on insulin and then start steroids, the situation often calls for a basal-bolus regimen, with mealtime rapid-acting insulin added to cover the midday and evening surges. This approach is well suited to people whose diabetes won’t resolve after the steroid stops. However, for people who develop new hyperglycemia solely from the steroid, a full basal-bolus regimen carries a higher risk of nighttime lows because the steroid’s glucose-raising effect fades overnight while the long-acting insulin keeps working.¹¹

High-Dose Steroid Situations

When patients receive very high doses of intravenous steroids, as happened frequently during the COVID-19 pandemic with high-dose methylprednisolone, the resulting hyperglycemia can be extreme and difficult to control with subcutaneous insulin alone. In those cases, continuous intravenous insulin infusions have been used to gradually bring blood sugar within target ranges, though some hyperglycemic episodes still occurred during the initial phase of the protocol.¹⁸ This intensive approach is reserved for hospital settings and illustrates how aggressively steroid-induced hyperglycemia sometimes needs to be treated.

What Happens When Steroids Are Tapered

One of the trickiest phases of managing steroid-induced blood sugar problems is the taper. As the steroid dose drops, the glucose-raising effect diminishes, and any insulin or medication you’ve been taking to counteract it may suddenly become too much. The risk of hypoglycemia climbs during the taper. Insulin doses need to be reduced in step with the steroid reduction, and blood sugar monitoring should actually increase during this period, not decrease.¹⁹

For people who developed new-onset hyperglycemia solely from the steroid, glucose levels typically return to normal once the drug is discontinued. But the timeline varies. Some people normalize within days; others take weeks. And for a subset, the steroid course unmasked latent diabetes that would have appeared eventually regardless. If your blood sugar hasn’t returned to normal several weeks after stopping a steroid, follow up with your doctor for a formal diabetes evaluation rather than assuming it will resolve on its own.

Steroid Effects on Appetite and Eating Patterns

Beyond the direct metabolic mechanisms, steroids influence blood sugar indirectly through appetite. Cortisol and its synthetic analogs act on brain pathways that increase carbohydrate craving and overall food intake. Activation of glucocorticoid receptors in the brain drives a natural surge in carbohydrate ingestion and metabolism, particularly at times when the body’s glycogen stores are low. Under stress or with exogenous steroids, these catabolic effects intensify, promoting both glucose production and the behavioral urge to eat high-carbohydrate foods. If you’ve ever been on prednisone and found yourself raiding the kitchen, the medication is partly to blame. Eating larger amounts of carbohydrate-rich food amplifies the blood sugar spikes that steroids are already causing through their metabolic effects, creating a feedback loop that can feel difficult to control.

Practical steps can blunt this effect. Eating smaller, more frequent meals with a focus on protein, healthy fats, and non-starchy vegetables rather than bread, rice, and sweets can modestly reduce the amplitude of postprandial glucose spikes. Timing carbohydrate intake earlier in the day, when insulin sensitivity is somewhat better, may also help, though this is harder to study rigorously. No dietary change will cancel out the metabolic effects of a high-dose steroid, but diet can influence the difference between a glucose level that is elevated and one that is dangerously elevated.

Steroids and Pregnancy

Pregnant women occasionally need corticosteroids, most commonly a short course of betamethasone or dexamethasone given before preterm delivery to accelerate fetal lung maturation. These injections reliably raise maternal blood sugar, and the effect is particularly concerning in women who already have gestational diabetes or are at risk for it. Cortisol production naturally increases during pregnancy and plays a role in the complex hormonal environment that can tip the balance toward insulin resistance. The addition of exogenous steroids on top of the pregnancy-related hormonal shifts can produce substantial hyperglycemia requiring temporary insulin therapy and close glucose monitoring for several days after the injection.

Women who receive antenatal steroids and have existing gestational diabetes should expect their management plan to change for the short term. Blood sugar targets remain the same, but achieving them usually requires increased insulin doses or the temporary addition of insulin if the woman was previously controlled on diet alone. The glucose effect of a two-dose betamethasone course typically peaks within one to two days and resolves within a week, though individual variation is significant.