Corticosteroid injections are a common and effective treatment used to reduce inflammation and pain in joints, tendons, and the spine. These potent medications, which mimic the hormone cortisol, provide localized relief for conditions like arthritis or sciatica. A temporary rise in blood sugar levels, known as hyperglycemia, is a common and expected side effect. This short-term glucose spike is a major concern, particularly for individuals managing diabetes or pre-diabetes.
How Corticosteroids Raise Glucose Levels
The mechanism behind the blood sugar elevation is directly related to how the injected steroid acts like the body’s natural stress hormone, cortisol. These corticosteroids immediately signal the liver to increase its output of glucose into the bloodstream. This process is called gluconeogenesis, where the liver creates new sugar from non-carbohydrate sources, such as protein.
Simultaneously, the steroid reduces the effectiveness of insulin, creating a condition called insulin resistance in the body’s muscle and fat cells. These peripheral tissues become less able to absorb glucose from the blood, meaning less sugar is cleared from circulation. The combination of the liver producing more glucose and the cells being less responsive to insulin results in a rapid and noticeable rise in blood sugar concentration. This effect is transient, but the body’s normal glucose regulation is significantly disrupted while the drug is active.
Factors Determining the Length of the Spike
The duration of the blood sugar elevation is not fixed and depends on several factors, including the specific drug and individual patient characteristics. The glucose level typically begins to rise within a few hours of the injection and often peaks around 8 to 12 hours post-procedure. For many patients, the most significant blood sugar changes occur within the first 24 to 48 hours following the injection.
The total length of the spike is determined primarily by the type of corticosteroid administered. Short-acting steroids, like hydrocortisone, have a relatively brief half-life, meaning their glucose-raising effect may subside within a day or two. However, most therapeutic injections use depot or longer-acting preparations, such as triamcinolone or dexamethasone, which are designed to release slowly over time.
With these longer-acting medications, the blood sugar can remain elevated for a much longer period. While some studies show a return to baseline within two to three days, other reports indicate that the hyperglycemic effect can persist for up to three weeks in certain individuals. This variability highlights the importance of sustained monitoring.
Patient-specific factors also significantly influence the magnitude and duration of the glucose spike. Individuals with poorly controlled pre-existing diabetes, often indicated by a higher baseline HbA1c level, typically experience a greater increase in their blood sugar after an injection. Similarly, patients who are already using insulin to manage their diabetes are prone to a more significant elevation in glucose levels.
Practical Steps for Glucose Management
Given the expected glucose elevation, proactive management is necessary to maintain a safe blood sugar range during the post-injection period. The most immediate step involves increasing the frequency of blood glucose monitoring. Patients with diabetes should test their blood sugar at least four times a day—before each meal and at bedtime—for the first few days following the injection. Monitoring should continue until readings have consistently returned to the patient’s pre-injection target range.
Dietary modifications can also help mitigate the glucose spike, especially during the first two days when the effect is typically strongest. Limiting the intake of high-glycemic carbohydrates and focusing on low-sugar foods assists the body’s impaired insulin function during the peak activity of the steroid.
Medication Adjustments and Safety
For patients managing diabetes with medication, temporary adjustments to the treatment plan are frequently necessary. Individuals may require a short-term increase in the dose of their oral diabetes medication or a higher amount of insulin to overcome the induced insulin resistance. It is necessary to consult with a physician or diabetes specialist before making any changes to medication doses, as self-adjusting can lead to dangerous hypoglycemia once the steroid effect wears off.
Patients must be vigilant for signs of high blood sugar, such as excessive thirst, frequent urination, fatigue, or blurred vision. If blood sugar readings remain persistently high, such as above 20 mmol/L (approximately 360 mg/dL), or if symptoms of severe hyperglycemia develop, a healthcare provider should be contacted immediately.