Can steroids affect HbA1c? Yes — corticosteroids such as prednisolone, dexamethasone, and hydrocortisone are well recognised for raising blood glucose levels, which can lead to a measurable rise in HbA1c over time. Whether you are taking steroids short-term or as part of a long-term treatment plan, understanding how they influence glycaemic control is essential for safe management. This article explains the mechanisms involved, which steroids carry the greatest risk, who is most vulnerable, and what monitoring and treatment steps are recommended under current UK guidance.
Summary: Yes, steroids can affect HbA1c — corticosteroids raise blood glucose through multiple mechanisms, and prolonged or repeated use can cause a measurable rise in HbA1c over time.
- Corticosteroids such as prednisolone, dexamethasone, and hydrocortisone raise blood glucose by stimulating hepatic gluconeogenesis, reducing insulin sensitivity, and impairing glucose uptake into tissues.
- HbA1c reflects average blood glucose over two to three months; a level of 48 mmol/mol (6.5%) or above meets the NICE NG28 diagnostic threshold for diabetes.
- HbA1c alone is not recommended for detecting acute steroid-induced hyperglycaemia — capillary or venous blood glucose monitoring is more appropriate for short-term assessment.
- Oral and intravenous corticosteroids carry the highest risk of raising HbA1c; inhaled, topical, and intra-articular steroids carry lower but non-negligible risk at high doses.
- Key risk factors for steroid-induced diabetes include pre-existing type 2 diabetes or pre-diabetes, obesity, older age, South Asian or Black African/Caribbean ethnicity, and long-term high-dose steroid use.
- Patients should not stop prescribed corticosteroids without medical advice, even if blood glucose rises, as abrupt discontinuation risks adrenal insufficiency.
Table of Contents
- How Steroids Affect Blood Glucose and HbA1c Levels
- Which Steroids Are Most Likely to Raise HbA1c
- Who Is at Greatest Risk of Steroid-Induced Diabetes
- Monitoring HbA1c During and After Steroid Treatment
- Managing High Blood Sugar Caused by Steroid Use
- When to Seek Medical Advice About Steroids and HbA1c
- Frequently Asked Questions
How Steroids Affect Blood Glucose and HbA1c Levels
Corticosteroids raise blood glucose by stimulating hepatic gluconeogenesis, reducing insulin sensitivity, and impairing glucose uptake; prolonged use can elevate HbA1c, though short-term courses may not be fully captured by this test.
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Corticosteroids — commonly prescribed medicines such as prednisolone, dexamethasone, and hydrocortisone — are well recognised for their ability to raise blood glucose levels. This effect occurs through several interconnected mechanisms. Steroids stimulate the liver to produce more glucose (a process called gluconeogenesis), reduce the sensitivity of cells to insulin, and impair the uptake of glucose into muscle and fat tissue. The result is a rise in circulating blood sugar, particularly after meals.
HbA1c (glycated haemoglobin) is a blood test that reflects average blood glucose levels over the preceding two to three months. Because haemoglobin becomes glycated in proportion to blood glucose exposure, prolonged or repeated steroid use can cause a measurable rise in HbA1c over time. However, it is important to understand that HbA1c is weighted towards more recent weeks and may remain within the normal range despite significant short-term glucose elevations during a brief steroid course. For this reason, HbA1c alone is not recommended for detecting or managing acute steroid-induced hyperglycaemia; capillary or venous blood glucose measurements are more appropriate for short-term monitoring and guiding treatment decisions. A random blood glucose of 11.1 mmol/L or above in the presence of symptoms is consistent with diabetes, in line with NICE NG28 criteria.
For those on long-term steroid therapy, HbA1c remains a clinically useful tool for monitoring overall glycaemic trends, with a level of 48 mmol/mol (6.5%) or above meeting the diagnostic threshold for diabetes (NICE NG28). The degree of any HbA1c elevation depends on the dose, duration, and type of steroid used, as well as the individual's underlying metabolic health. In some people, steroid-induced glucose rises may be transient and resolve once treatment ends, and HbA1c may not fully capture the extent of short-term glucose disturbance.
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Which Steroids Are Most Likely to Raise HbA1c
Oral and intravenous corticosteroids — particularly prednisolone and dexamethasone — carry the highest risk; inhaled and topical steroids are lower risk but can still raise glucose at high doses or with prolonged use.
Not all corticosteroids carry the same risk of raising blood glucose or HbA1c. The likelihood and magnitude of effect depend largely on the potency, dose, route of administration, and timing of the steroid in question.
Oral and intravenous corticosteroids carry the highest risk, as they achieve significant systemic concentrations. The most commonly implicated include:
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Prednisolone — widely used for inflammatory and autoimmune conditions; a frequent cause of steroid-induced hyperglycaemia. A morning dose of prednisolone characteristically causes post-lunch and evening glucose spikes, which is relevant to monitoring and treatment timing.
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Dexamethasone — highly potent, often used in oncology and acute settings; associated with pronounced post-meal glucose rises.
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Hydrocortisone — used in adrenal insufficiency and acute illness; shorter-acting but still capable of raising glucose.
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Methylprednisolone — used in high-dose pulses for conditions such as multiple sclerosis relapses.
The prescribing information (Summary of Product Characteristics, SmPC) for oral prednisolone and dexamethasone, available via the MHRA/EMC, lists hyperglycaemia and diabetes mellitus as recognised adverse effects.
Inhaled corticosteroids (such as beclometasone or fluticasone) are generally considered lower risk due to minimal systemic absorption at standard doses. However, high-dose inhaled steroids used over prolonged periods may still contribute modestly to glucose elevation in susceptible individuals, as noted in the relevant SmPCs.
Topical and intra-articular steroids are similarly lower risk, though repeated or high-dose use — especially under occlusive dressings — can result in some systemic absorption. Intra-articular steroid injections (for example, triamcinolone) can cause transient hyperglycaemia lasting several days, which is particularly relevant for people with diabetes. The SmPCs for topical preparations such as clobetasol and hydrocortisone cream acknowledge the potential for systemic effects with prolonged or extensive use. Clinicians should consider the metabolic risk across all routes of administration, particularly in patients with pre-existing diabetes or risk factors for it.
Who Is at Greatest Risk of Steroid-Induced Diabetes
People with pre-existing type 2 diabetes, pre-diabetes, obesity, older age, or South Asian and Black African/Caribbean ethnicity are at greatest risk of steroid-induced diabetes and HbA1c elevation.
Steroid-induced diabetes (also referred to as steroid-induced hyperglycaemia) does not affect everyone who takes corticosteroids. Certain individuals are considerably more vulnerable, and identifying these patients before or at the start of steroid treatment is an important aspect of safe prescribing.
Key risk factors include:
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A personal history of type 2 diabetes or pre-diabetes (impaired fasting glucose or impaired glucose tolerance)
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A family history of type 2 diabetes
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Overweight or obesity — noting that South Asian, Black African, and Black Caribbean individuals may be at increased risk at a lower BMI threshold (≥23 kg/m²), compared with the general population threshold of ≥25 kg/m²
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Older age (particularly over 60 years)
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South Asian, Black African, or Black Caribbean ethnicity, which carries a higher baseline risk of type 2 diabetes
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Polycystic ovary syndrome (PCOS)
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Previous gestational diabetes
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Existing insulin resistance
People who require long-term, high-dose corticosteroid therapy — for example, those with rheumatoid arthritis, inflammatory bowel disease, or organ transplants — are at particular risk of sustained HbA1c elevation and the development of frank diabetes. NICE guidance (NG28 and PH38 on prevention of type 2 diabetes in high-risk individuals) and the Joint British Diabetes Societies for Inpatient Care (JBDS-IP) guideline on steroid-induced hyperglycaemia all highlight the importance of identifying at-risk individuals and implementing appropriate monitoring.
It is also important to note that steroid-induced diabetes can develop even in individuals with no prior history of glucose abnormality. In such cases, the condition may go unrecognised without proactive monitoring, underscoring the importance of awareness among both clinicians and patients.
Monitoring HbA1c During and After Steroid Treatment
Baseline HbA1c or fasting glucose should be checked before starting higher-dose steroids, with daily capillary glucose monitoring during treatment and a repeat HbA1c approximately three months after stopping.
Appropriate monitoring of blood glucose and HbA1c is essential for anyone receiving corticosteroid therapy, particularly those on long-term or high-dose regimens. The JBDS-IP guideline on management of hyperglycaemia and steroid therapy, alongside NICE CKS guidance on oral corticosteroids, provides the primary framework for monitoring in UK practice.
For patients without a prior diabetes diagnosis who are starting higher-dose glucocorticoids (for example, prednisolone 20 mg/day or above):
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Check a baseline HbA1c or fasting glucose before or at the start of treatment to identify pre-existing dysglycaemia.
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During treatment, check capillary blood glucose once daily (ideally one to two hours after the main meal, or before the evening meal, to capture the characteristic post-lunch/evening peak with morning prednisolone).
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If capillary glucose exceeds 11.1 mmol/L on two separate occasions, increase monitoring to four times daily (before meals and at bedtime) and seek clinical advice promptly.
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Repeat HbA1c approximately three months after stopping steroids to reassess glycaemic status and confirm whether any glucose abnormality has resolved.
For patients already known to have diabetes:
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Check capillary blood glucose at least four times daily during steroid initiation or dose increases, and adjust glucose-lowering therapy accordingly.
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More frequent HbA1c testing may be appropriate during prolonged steroid courses.
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Steroids often cause a characteristic pattern of post-meal (postprandial) hyperglycaemia, which may not be fully reflected in fasting glucose measurements alone.
After completing a course of steroids, blood glucose levels and HbA1c may gradually return to baseline, particularly if the treatment was short-term. However, in some individuals — especially those with underlying insulin resistance — glucose abnormalities may persist. Any patient who developed steroid-induced diabetes should be reviewed to determine whether ongoing management is required.
| Steroid / Route | Examples | Risk of Raising HbA1c / Glucose | Characteristic Pattern | Key Monitoring Advice |
|---|---|---|---|---|
| Oral corticosteroids | Prednisolone, dexamethasone, methylprednisolone | High — significant systemic exposure | Post-lunch and evening glucose spikes with morning dosing | Baseline HbA1c or fasting glucose; daily capillary glucose 1–2 hrs after main meal |
| Intravenous corticosteroids | Hydrocortisone, methylprednisolone, dexamethasone | High — rapid systemic delivery | Pronounced postprandial hyperglycaemia | At least four times daily capillary glucose monitoring; adjust insulin promptly |
| Inhaled corticosteroids | Beclometasone, fluticasone | Low at standard doses; modest risk at high prolonged doses | Diffuse, less pronounced glucose elevation | Routine monitoring unless high-dose or prolonged; review SmPC |
| Intra-articular injection | Triamcinolone | Low–moderate; transient systemic absorption | Transient hyperglycaemia lasting several days post-injection | Warn patients with diabetes; monitor capillary glucose for 3–5 days post-injection |
| Topical corticosteroids | Clobetasol, hydrocortisone cream | Low; higher risk with occlusive dressings or extensive use | Mild, variable glucose elevation with prolonged use | Consider systemic effects if used extensively; consult SmPC |
| HbA1c monitoring (long-term use) | All systemic steroids | HbA1c ≥48 mmol/mol (6.5%) meets NICE NG28 diabetes threshold | HbA1c weighted to recent weeks; may underestimate short-term spikes | Repeat HbA1c ~3 months after stopping steroids to confirm glycaemic status |
| Acute hyperglycaemia action threshold | All routes | Capillary glucose >11.1 mmol/L on two occasions requires escalation | HbA1c alone insufficient for acute detection; use capillary/venous glucose | Increase to four times daily monitoring; consider gliclazide or NPH insulin (JBDS-IP) |
Managing High Blood Sugar Caused by Steroid Use
Management is tailored to hyperglycaemia severity and steroid duration; gliclazide or NPH insulin are commonly used, and SGLT2 inhibitors should not be initiated during acute steroid therapy due to DKA risk.
When corticosteroids cause a clinically significant rise in blood glucose or HbA1c, management should be tailored to the individual's circumstances, including the severity of hyperglycaemia, the expected duration of steroid treatment, and any pre-existing diabetes management plan. The JBDS-IP steroid hyperglycaemia treatment algorithm provides detailed UK guidance for both inpatient and outpatient settings.
For patients with pre-existing type 2 diabetes, adjustments to existing medication are often necessary. This might involve increasing the dose of oral glucose-lowering agents or initiating insulin. Because steroids predominantly raise post-meal glucose, treatment should be timed to address this pattern — for example, using a morning dose of intermediate-acting (NPH) insulin alongside a morning prednisolone regimen.
For patients who develop new-onset steroid-induced hyperglycaemia, the JBDS-IP guideline recommends the following stepwise approach in outpatient settings:
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Persistent post-lunch or evening glucose above 11.1 mmol/L: consider starting gliclazide (a sulphonylurea) and titrate the dose according to response. Gliclazide is often preferred as a first-line oral agent in this context due to its action profile.
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If oral agents are insufficient or glucose is persistently high: consider morning intermediate-acting (NPH) insulin, timed to match the steroid's pharmacokinetic profile.
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If readings are persistently above 20 mmol/L, or the patient is symptomatic: seek urgent clinical review, as insulin therapy is likely to be required.
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Mild hyperglycaemia may initially be supported by dietary modification — reducing refined carbohydrates and sugary foods, eating smaller and more frequent meals, and increasing physical activity where possible — but this should not delay pharmacological treatment if glucose targets are not met.
Important cautions:
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SGLT2 inhibitors (such as dapagliflozin or empagliflozin) should not be initiated during acute steroid therapy. Patients already taking an SGLT2 inhibitor who become unwell or are starting steroids should follow sick-day rules and monitor blood ketones, given the risk of euglycaemic diabetic ketoacidosis (DKA), as highlighted in the MHRA Drug Safety Update on SGLT2 inhibitors.
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If steroids are being tapered or discontinued, glucose-lowering therapy may need to be reduced accordingly to prevent hypoglycaemia.
Close communication between the patient, GP, and any specialist involved in their care is essential throughout this period.
When to Seek Medical Advice About Steroids and HbA1c
Seek same-day GP or NHS 111 advice if blood glucose exceeds 15 mmol/L on two occasions; call 999 if glucose is persistently above 20 mmol/L or symptoms of DKA such as vomiting, drowsiness, or raised ketones develop.
Knowing when to seek medical advice is an important aspect of patient safety for anyone taking corticosteroids. Whilst not everyone on steroids will experience significant glucose disturbance, certain symptoms and circumstances warrant prompt contact with a GP or healthcare professional.
Contact your GP or healthcare team if you experience:
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Increased thirst or a dry mouth that does not resolve
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Passing urine more frequently than usual, particularly at night
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Unexplained fatigue or lethargy
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Blurred vision
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Headaches or difficulty concentrating
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Slow-healing wounds or recurrent infections
These may be signs of hyperglycaemia (high blood sugar) and should be assessed without delay. Patients with known diabetes who notice their blood glucose readings are consistently higher than their usual target range whilst on steroids should contact their diabetes care team for guidance on medication adjustment.
Contact your GP or NHS 111 the same day if your blood glucose reading is above 15 mmol/L on two or more occasions, or if you develop any of the symptoms listed above.
Seek urgent medical attention — call 999 or go to your nearest emergency department — if you experience symptoms that may suggest very high blood sugar or diabetic ketoacidosis (DKA), such as:
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Blood glucose persistently above 20 mmol/L
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Nausea, vomiting, or abdominal pain
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Drowsiness or confusion
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Blood ketones of 1.5 mmol/L or above (or moderate to large ketones on urine testing)
People with type 1 diabetes, or those taking an SGLT2 inhibitor, should check blood ketones whenever they feel unwell or if their glucose is unexpectedly high, as they are at increased risk of DKA.
It is equally important not to stop taking prescribed corticosteroids without medical advice, even if blood glucose rises. Abrupt discontinuation can cause adrenal insufficiency, which carries its own serious risks. Any concerns about steroid use and its effects on HbA1c or blood glucose should be discussed openly with the prescribing clinician, who can weigh the benefits and risks and adjust the treatment plan accordingly.
If you believe you have experienced a side effect from a corticosteroid, you can report this to the MHRA Yellow Card scheme (available at yellowcard.mhra.gov.uk). This helps the MHRA monitor the safety of medicines used in the UK. The NHS and NICE both emphasise shared decision-making in the management of long-term steroid therapy.
Frequently Asked Questions
Can a short course of steroids raise my HbA1c result?
A brief steroid course can cause significant short-term glucose spikes, but HbA1c — which reflects average glucose over two to three months — may not rise noticeably unless steroid use is prolonged or repeated. Capillary blood glucose monitoring is more reliable for detecting acute steroid-induced hyperglycaemia.
Will my blood glucose and HbA1c return to normal after stopping steroids?
In many people, blood glucose and HbA1c gradually return to baseline after steroids are stopped, particularly following a short course. However, individuals with underlying insulin resistance or pre-diabetes may have persistent glucose abnormalities, and a repeat HbA1c around three months after stopping is recommended to confirm recovery.
Should I stop taking my steroids if my blood glucose goes up?
No — you should not stop prescribed corticosteroids without medical advice, as abrupt discontinuation can cause adrenal insufficiency, which is a serious medical risk. Instead, contact your GP or diabetes care team so that your blood glucose can be managed safely alongside your steroid treatment.
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