How can a patient with type 1 diabetes (T1D) manage blood glucose levels while taking corticosteroids (steroids)?

Managing Blood Glucose in Type 1 Diabetes Patients on Corticosteroids

For patients with type 1 diabetes on corticosteroids, continue basal insulin at baseline doses and add NPH insulin (0.3-0.5 units/kg/day) given in the morning to match the steroid's peak hyperglycemic effect, while increasing prandial insulin by 40-60% or more, with frequent glucose monitoring every 2-4 hours targeting 100-180 mg/dL. 1, 2

Critical First Principle: Never Stop Basal Insulin

• Patients with type 1 diabetes must continue their basal insulin even if eating patterns change or steroids are started, as they have no endogenous insulin production 1
• This is non-negotiable and prevents diabetic ketoacidosis 1

Understanding the Steroid Effect Pattern

• Corticosteroids cause hyperglycemia through impaired beta cell function, increased insulin resistance, and enhanced hepatic glucose production 2
• The hyperglycemic effect is most pronounced in the afternoon and evening (6-9 hours post-dose), often normalizing overnight even without treatment 2, 3
• This diurnal pattern means fasting glucose alone will miss the peak effect and lead to undertreatment 2

Insulin Adjustment Algorithm

For Once-Daily Short-Acting Steroids (Prednisone, Methylprednisolone):

• Add NPH insulin at 0.3-0.5 units/kg/day given in the morning (same time as steroid dose) 1, 2
• NPH peaks 4-6 hours after administration, perfectly matching the steroid's peak hyperglycemic effect 1, 2
• Increase prandial (mealtime) rapid-acting insulin by 40-60% or more above baseline doses 1, 2
• For higher steroid doses, extraordinary increases in prandial insulin may be needed 1, 2

For Long-Acting Steroids (Dexamethasone) or Multiple Daily Doses:

• Increase long-acting basal insulin dose AND add NPH insulin 1, 2, 4
• The 24-hour hyperglycemic effect requires both components to control fasting and daytime glucose 1, 3
• Initial NPH dosing: 0.1-0.2 units/kg/day, with potential increases to 0.3-0.5 units/kg/day 4

Monitoring Strategy

• Monitor glucose every 2-4 hours initially, not just fasting values 2, 4
• Target range: 100-180 mg/dL (5.6-10.0 mmol/L) 1, 2
• Pay particular attention to 2-hour post-lunch readings (around 2-3 PM) as this captures the peak steroid effect 2
• Adjust insulin doses daily based on patterns and anticipated steroid dose changes 1, 2

Dose Titration Protocol

• If target glucose not achieved, increase NPH by 2 units every 3 days 2, 4
• Adjust prandial insulin based on carbohydrate intake and correction needs 1
• As steroid doses taper, proportionally reduce insulin doses immediately to prevent hypoglycemia 2

Critical Pitfalls to Avoid

• Do not rely on sliding-scale correction insulin alone - this approach is associated with poor glycemic control and has been discouraged in guidelines 2, 4
• Do not wait for fasting hyperglycemia to appear before treating - this misses the peak effect and delays intervention 2
• Do not forget to reduce insulin when steroids are tapered - this is a common cause of severe hypoglycemia 2
• Do not use only fasting glucose for monitoring - this will underestimate severity 2

Special Considerations for Type 1 Diabetes

• Maintain carbohydrate counting and insulin-to-carbohydrate ratios, but expect to increase ratios significantly 1
• Continue frequent self-monitoring of blood glucose at critical times (before meals, 2 hours post-meal, bedtime) 1
• Always carry rapid-acting insulin and glucose sources for hypoglycemia management 1
• Recognize that stress from the underlying condition requiring steroids also increases insulin resistance 1

If Receiving Enteral/Parenteral Nutrition

• Calculate nutritional insulin as 1 unit per 10-15 grams of carbohydrate in the formula 1
• NPH can be given every 8-12 hours to cover continuous feeds 1
• If feeds are interrupted, start dextrose infusion immediately to prevent hypoglycemia in type 1 diabetes patients 1

Drug Interaction Alert

• Corticosteroids directly antagonize insulin's glucose-lowering effect and are listed as substances that reduce insulin efficacy 5, 6
• Antidiabetic agent dosage adjustments are required when corticosteroids are started 6