What is the appropriate treatment for prednisone‑induced hyperglycaemia?

Treatment of Prednisone-Induced Hyperglycemia

For patients on prednisone with elevated blood sugars, initiate NPH insulin at 0.3-0.5 units/kg/day given in the morning to match the afternoon peak hyperglycemic effect, and adjust doses proportionally as steroids are tapered. 1, 2

Understanding the Hyperglycemic Pattern

Prednisone causes a distinct circadian pattern of glucose elevation that is critical to understand for effective treatment:

• Peak hyperglycemia occurs 6-9 hours after morning prednisone administration, corresponding to afternoon and evening elevations, with glucose often normalizing overnight even without treatment 2, 3
• The degree of hyperglycemia directly correlates with steroid dose—higher doses (≥50 mg) cause more significant elevations and will likely require insulin therapy 1, 2
• Steroids induce hyperglycemia through multiple mechanisms: impaired beta cell insulin secretion, increased total body insulin resistance, and enhanced hepatic gluconeogenesis 4, 1

Immediate Monitoring Protocol

Implement four-times-daily glucose monitoring (fasting and 2 hours after each meal) rather than relying on fasting glucose alone, which will miss the peak hyperglycemic effect 2, 3:

• Target glucose range: 5-10 mmol/L (90-180 mg/dL) 1, 2
• Pay particular attention to afternoon and evening readings, as these reflect the peak steroid effect 2, 3
• Provide patients with a blood glucose meter for self-monitoring 1

Treatment Algorithm Based on Severity

For Mild Hyperglycemia (Glucose 10-15 mmol/L)

• Oral agents such as metformin and gliclazide can be used as first-line therapy in patients with preserved renal and hepatic function 2
• Metformin may attenuate other metabolic effects of steroids 3, 5

For Moderate to Severe Hyperglycemia (Glucose >15 mmol/L or on High-Dose Steroids ≥50 mg)

Oral agents alone are insufficient—insulin therapy is required 1, 3:

• NPH insulin is the preferred agent because its 4-6 hour peak action aligns perfectly with the peak hyperglycemic effect of morning glucocorticoid doses 2, 3
• Starting dose: 0.3-0.5 units/kg/day given in the morning (simultaneously with or 3 hours after steroid administration) 1, 2, 3
• For patients on high-dose glucocorticoids (prednisone ≥50 mg), those with higher baseline HbA1c, or pre-existing diabetes, increase the starting dose by 40-60% 3
• For elderly patients or those with renal impairment, start with lower doses (0.2-0.3 units/kg/day) 1

Dose Adjustment Strategy

As steroids are tapered, insulin doses must be proportionally decreased to prevent hypoglycemia 1, 2, 3:

• Decrease insulin dose by the same percentage as the steroid dose reduction 3
• Adjust insulin based on blood glucose patterns, focusing on afternoon/evening readings 1, 2
• Review insulin doses whenever adjustments to steroids are made 3

Special Situations

Night-Time Prednisone Dosing

• When prednisone is taken at night, switch from NPH to long-acting basal insulin (glargine or detemir) given at bedtime, as the hyperglycemic pattern peaks overnight and into the following day 2

Dexamethasone or Continuous Glucocorticoid Use

• Long-acting basal insulin may be required to control fasting blood glucose 2

Critical Warning Signs Requiring Immediate Hospital Referral

Patients with the following require immediate medical attention 2, 3:

• Blood glucose >15 mmol/L with ketones >2 mmol/L
• Glucose persistently >20 mmol/L (or reading "HI" on meter)
• Symptoms of diabetic ketoacidosis or hyperosmolar hyperglycemic state 1, 3

Common Pitfalls to Avoid

• Using only fasting glucose for monitoring—this misses the peak steroid effect that occurs in the afternoon 2, 3
• Relying solely on sliding-scale correction insulin—this is associated with poor glycemic control 2
• Not reducing insulin doses proportionally when steroids are tapered—this leads to hypoglycemia 1, 2, 3
• Using glargine-based regimens for morning prednisone—these may under-treat daytime hyperglycemia and cause nocturnal hypoglycemia 6

Patient Education Requirements

All patients must receive comprehensive education on 1, 2, 3:

• Glucose monitoring technique and frequency (four times daily)
• Symptoms of severe hyperglycemia (polyuria, polydipsia, fatigue, blurred vision)
• Emergency thresholds: persistent glucose >20 mmol/L requires immediate hospital presentation
• Hypoglycemia symptoms and management as insulin is initiated
• The importance of adjusting insulin doses when steroid doses change

Shared Care Approach

Early communication and shared care with a primary care physician is recommended for all patients with hyperglycemia, with referral to endocrinology where insulin is expected to be required 4.