For a patient on prednisone 60 mg who cannot use insulin glargine (Lantus) and wants to stop NPH 46 units basal insulin, what fixed pre‑meal rapid‑acting insulin dose should be given with each of three meals?

Fixed Meal‑Dose Rapid‑Acting Insulin Regimen Without NPH or Lantus

For a patient on prednisone 60 mg who cannot use NPH 46 units or Lantus 15 units with meals, initiate rapid‑acting insulin at 15 units before each of the three main meals (breakfast, lunch, dinner) to provide a total of 45 units daily prandial coverage.

Rationale for the 15‑Unit Fixed Meal Dose

• The patient's prior regimen included NPH 46 units (providing daytime basal coverage) plus Lantus 15 units with each meal (totaling 45 units prandial), for a combined 91 units/day 1.
• High‑dose prednisone (60 mg) induces severe insulin resistance, typically requiring 40–60 % higher insulin doses than standard recommendations 1, 2.
• When omitting all basal insulin (both NPH and Lantus), the entire glucose‑lowering burden shifts to prandial insulin; therefore, each meal dose must be substantially higher than the 4–6 units typically used in basal‑bolus initiation 1, 3.
• A fixed 15‑unit dose per meal (totaling 45 units daily) approximates the prandial component of the prior regimen and accounts for the steroid‑induced hyperglycemia that peaks 4–12 hours after the morning prednisone dose 2.

Timing and Administration

• Administer rapid‑acting insulin (lispro, aspart, or glulisine) 0–15 minutes before each meal to achieve optimal post‑prandial glucose control 1, 4.
• The lunch and dinner doses are particularly critical because prednisone‑induced hyperglycemia predominantly affects afternoon and evening glucose levels 2.

Correction‑Insulin Protocol (Adjunct to Fixed Meal Doses)

• Add 2 units of rapid‑acting insulin for pre‑meal glucose > 250 mg/dL 1.
• Add 4 units for pre‑meal glucose > 350 mg/dL 1.
• These correction units are in addition to the scheduled 15‑unit meal dose 1.

Monitoring Requirements

• Check capillary glucose before each meal and at bedtime (minimum four times daily) to guide dose adjustments 1, 3.
• Obtain 2‑hour post‑prandial glucose after each meal to assess prandial adequacy; target < 180 mg/dL 1, 3.
• Daily fasting glucose checks are essential even without basal insulin, as overnight hepatic glucose production will be unopposed 1.

Titration Protocol

• Increase each meal dose by 2 units every 3 days if the 2‑hour post‑prandial glucose consistently exceeds 180 mg/dL 1, 3.
• If hypoglycemia (< 70 mg/dL) occurs, reduce the implicated meal dose by 10–20 % (≈2–3 units) immediately 1, 2.
• Expect to require 18–20 units per meal (total 54–60 units daily) after full titration, given the severity of steroid‑induced insulin resistance 2.

Critical Safety Considerations

Fasting Hyperglycemia Risk

• Without basal insulin, fasting glucose will likely exceed 200–300 mg/dL because hepatic glucose production is completely unopposed overnight 1, 5.
• If fasting glucose consistently exceeds 180 mg/dL, this regimen is inadequate and basal insulin must be reintroduced (e.g., NPH 20–30 units in the morning or glargine 20–25 units at bedtime) 1, 2.

Hypoglycemia Prevention

• Never administer rapid‑acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk 1.
• Treat glucose < 70 mg/dL promptly with 15 g fast‑acting carbohydrate, recheck in 15 minutes, and repeat if needed 1.

Steroid Taper Adjustments

• When prednisone is reduced, decrease each meal dose by 20–30 % (≈3–5 units) for every 20 mg prednisone reduction to prevent hypoglycemia 2.
• Upon complete prednisone cessation, insulin needs may drop by 50–70 %, requiring meal doses of 5–7 units each 2.

Alternative Regimen if Fasting Hyperglycemia Develops

• If fasting glucose remains > 180 mg/dL for three consecutive days, add NPH 20–30 units in the morning (administered with the prednisone dose) to provide daytime basal coverage 2.
• Alternatively, add glargine 20–25 units at bedtime to suppress overnight hepatic glucose production 1, 6, 7.
• Continue the 15‑unit fixed meal doses alongside the reintroduced basal insulin 1, 3.

Common Pitfalls to Avoid

• Do not rely solely on correction insulin without scheduled meal doses; this approach (sliding‑scale monotherapy) is condemned by major diabetes guidelines and leads to dangerous glucose fluctuations 1, 8.
• Do not delay increasing meal doses when post‑prandial glucose repeatedly exceeds 180 mg/dL on high‑dose steroids 1, 2.
• Do not use premixed insulin (e.g., 70/30) in this context, as it offers limited flexibility for rapid dose adjustments and is associated with high hypoglycemia rates 1.
• Do not continue this regimen long‑term without basal insulin, as unopposed fasting hyperglycemia will lead to poor overall glycemic control and increased complication risk 1, 5.

Expected Clinical Outcomes

• With properly implemented fixed meal‑dose therapy, ≈68 % of patients achieve mean glucose < 140 mg/dL, compared with ≈38 % using sliding‑scale insulin alone 1, 8.
• Total daily insulin requirements on prednisone 60 mg typically reach 60–80 units/day (≈18–20 units per meal after titration) 2.
• Fasting glucose will remain elevated (150–250 mg/dL) without basal insulin, but post‑prandial control should improve significantly 1, 5.