For a patient receiving 26 units of insulin for 215 g of carbohydrate over an 18‑hour period, what insulin dose should be used if the same carbohydrate load is administered over a 12‑hour cycle?

Insulin Dose Adjustment for Shortened Enteral Feeding Cycle

Increase the insulin dose to approximately 39 units to maintain the same carbohydrate-to-insulin ratio when compressing the feeding schedule from 18 hours to 12 hours.

Calculation Method

• The standard approach for continuous enteral feeding is to provide approximately 1 unit of insulin per 10–15 g of carbohydrate in the formula, adjusted for the infusion rate and duration.1
• Your current regimen delivers 215 g carbohydrate over 18 hours with 26 units insulin, yielding a ratio of approximately 1 unit per 8.3 g carbohydrate.1
• When the same 215 g carbohydrate load is compressed into 12 hours instead of 18 hours, the infusion rate increases by 50 % (18 ÷ 12 = 1.5), requiring a proportional increase in insulin to match the accelerated glucose delivery.1
• The new insulin dose should be 26 units × 1.5 = 39 units to maintain equivalent glycemic control.1

Insulin Delivery Strategy for 12-Hour Cycle

• For continuous enteral feeding over 12 hours, administer the nutritional insulin component using NPH insulin every 12 hours or regular insulin every 6 hours to provide steady coverage throughout the feeding period.1
• A practical regimen is NPH 20 units at the start of the feeding cycle (covering the first 12 hours) plus regular insulin 6–7 units every 6 hours during the feeding window.1
• Alternatively, give regular insulin 10 units every 4 hours (three doses over 12 hours totaling 30 units) plus a small basal component.1

Basal Insulin Continuation

• Continue prior basal insulin unchanged (or if none exists, calculate approximately 30–50 % of the total daily dose as basal insulin given once daily with glargine or degludec).1
• If the patient was previously on basal insulin, maintain that dose because basal needs are independent of feeding schedule; only the nutritional component (the 26 → 39 units) changes.1
• A reasonable starting basal dose for a patient without prior insulin is 5 units NPH every 12 hours or 10 units glargine daily.1

Correction Insulin Protocol

• Add subcutaneous regular insulin every 6 hours or rapid-acting insulin every 4 hours as correction doses for hyperglycemia, separate from the scheduled nutritional insulin.1
• Use a simplified correction scale: 2 units for glucose > 250 mg/dL and 4 units for glucose > 350 mg/dL.1, 2

Monitoring and Titration

• Check point-of-care glucose every 4–6 hours during the feeding cycle and adjust the nutritional insulin dose daily based on glucose patterns.1
• If glucose remains > 180 mg/dL despite the 39-unit dose, increase the nutritional insulin by 10–15 % (≈ 4 units) every 1–2 days until target glucose 140–180 mg/dL is achieved.1, 2
• If hypoglycemia (< 70 mg/dL) occurs, reduce the nutritional insulin dose by 10–20 % immediately and treat with 15 g fast-acting carbohydrate if the patient can take oral intake.1, 2

Critical Considerations When Feeding Is Interrupted

• If the enteral feeding is stopped or interrupted, immediately start a dextrose infusion (D10W at 40 mL/h or D5W at higher rate) to prevent hypoglycemia, because the nutritional insulin will continue acting.1
• Never discontinue basal insulin even if feeding stops, as basal insulin suppresses hepatic glucose production independent of nutritional intake.1, 2
• Hold or reduce the nutritional insulin component by 50–75 % if feeding is interrupted, but continue basal insulin and correction doses.1

Common Pitfalls to Avoid

• Do not use the same 26-unit dose when compressing the feeding schedule, as the faster carbohydrate delivery will cause marked hyperglycemia.1
• Do not rely solely on correction (sliding-scale) insulin without scheduled nutritional insulin; this reactive approach is condemned by major diabetes guidelines and leads to dangerous glucose fluctuations.1, 2
• Avoid giving rapid-acting insulin at bedtime as a sole correction dose if the feeding cycle ends in the evening, as this markedly raises nocturnal hypoglycemia risk.1, 2
• Do not forget to adjust the insulin regimen back down if the feeding schedule is later extended again or if the patient transitions to oral intake.1

Alternative Dosing Approach (Conservative Start)

• If concerned about hypoglycemia risk, begin with 33 units (≈ 27 % increase from 26 units) and titrate upward by 2–4 units every 1–2 days based on glucose monitoring, rather than immediately jumping to the calculated 39 units.1, 2
• This conservative approach is particularly appropriate for elderly patients (> 65 years), those with renal impairment, or patients with poor prior glycemic data.1, 2