Insulin Therapy for Steroid-Induced Hyperglycemia in Non-Insulin-Dependent Diabetic Patients
For a non-insulin-dependent diabetic patient on prednisone with markedly elevated blood glucose, initiate basal insulin immediately at 10 units once daily (or 0.1–0.2 units/kg) and add rapid-acting insulin 4–6 units before lunch and dinner to counteract the afternoon/evening hyperglycemic peak caused by morning prednisone dosing. 1, 2
Immediate Insulin Initiation
Start basal insulin (glargine or detemir) at 10 units once daily at bedtime for patients with fasting glucose ≥180 mg/dL or symptomatic hyperglycemia, continuing metformin unless contraindicated. 1 For patients with more severe hyperglycemia (glucose >300 mg/dL or A1C ≥9%), consider higher starting doses of 0.3–0.5 units/kg/day split between basal and prandial insulin. 1
Add prandial rapid-acting insulin (lispro, aspart, or glulisine) at 4–6 units before lunch and dinner to address the characteristic steroid-induced afternoon/evening hyperglycemia pattern. 2, 3, 4 Glucocorticoid therapy typically increases insulin requirements by 40–60% beyond baseline needs, with the hyperglycemic peak occurring 4–12 hours after morning prednisone administration. 2, 3
Titration Protocol for Steroid-Induced Hyperglycemia
Increase basal insulin by 4 units every 3 days if fasting glucose remains ≥180 mg/dL, or by 2 units every 3 days if fasting glucose is 140–179 mg/dL, targeting 80–130 mg/dL. 1, 2 Increase prandial insulin doses by 2 units every 3 days based on 2-hour postprandial glucose readings, aiming for <180 mg/dL. 1, 2
When basal insulin approaches 0.5 units/kg/day without achieving glycemic targets, intensify prandial insulin rather than continuing to escalate basal insulin alone to avoid "overbasalization" with increased hypoglycemia risk. 1, 2
Metformin Optimization
Continue metformin at maximum tolerated dose (up to 2000–2550 mg daily) when adding insulin, as this combination reduces total insulin requirements by 20–30% and provides superior glycemic control compared to insulin alone. 1, 2 Metformin should not be discontinued when starting insulin unless specific contraindications exist (acute infection, renal impairment, tissue hypoxia). 1
Monitoring Requirements
Check fasting glucose daily during titration to guide basal insulin adjustments, and measure pre-meal glucose before lunch and dinner plus 2-hour postprandial glucose after these meals to guide prandial insulin titration. 1, 2 If any glucose reading falls <70 mg/dL, immediately reduce the implicated insulin dose by 10–20% and treat with 15 grams of fast-acting carbohydrate. 1, 2
Steroid-Specific Insulin Adjustments
Morning prednisone dosing requires higher prandial insulin at lunch (6–8 units) and dinner (8–10 units) compared to breakfast (4 units or none), reflecting the 4–12 hour delay between steroid administration and peak hyperglycemic effect. 2, 3 Consider splitting NPH insulin into twice-daily dosing (e.g., 14 units morning, 10 units bedtime) or increasing morning NPH to 24–28 units to provide adequate daytime basal coverage during peak steroid effect. 2, 3
As prednisone is tapered or discontinued, reduce total daily insulin by 40–60% proportionally to reflect the waning steroid effect and prevent hypoglycemia. 2, 3
Alternative Oral Agent Considerations
Alpha-glucosidase inhibitors (acarbose) may be added to address postprandial hyperglycemia by delaying carbohydrate absorption, though their efficacy is modest compared to prandial insulin. 3 Sulfonylureas should be discontinued or reduced by 50% when initiating insulin to prevent additive hypoglycemia risk. 1, 2
Expected Clinical Outcomes
With appropriately weight-based basal-bolus therapy, approximately 68% of patients achieve mean glucose <140 mg/dL, compared with only 38% using sliding-scale insulin alone. 1, 2 Anticipated A1C reduction of 2–3% over 3–6 months is achievable with intensive insulin titration combined with metformin. 1
Critical Pitfalls to Avoid
Never delay insulin initiation in patients with glucose consistently >250 mg/dL on oral agents alone, as prolonged hyperglycemia exposure increases complication risk. 1, 2 Never discontinue metformin when starting insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain. 1, 2
Never rely solely on correction (sliding-scale) insulin without scheduled basal and prandial doses, as this reactive approach is condemned by major diabetes guidelines and produces dangerous glucose fluctuations. 1, 2 Never continue escalating basal insulin beyond 0.5–1.0 units/kg/day without addressing postprandial hyperglycemia, as this causes overbasalization with increased hypoglycemia and suboptimal control. 1, 2
Never give rapid-acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk. 1, 2