What is an insulin regimen for a newly diagnosed adult with type 1 diabetes and no significant comorbidities, using Humalog (insulin lispro) for prandial and correction doses together with a long‑acting basal insulin (e.g., insulin glargine or insulin detemir)?

Type 1 Diabetes Insulin Protocol Using Humalog (Insulin Lispro)

Initial Total Daily Insulin Dose Calculation

For a newly diagnosed adult with type 1 diabetes and no significant comorbidities, start with a total daily insulin dose of 0.5 units/kg/day, divided approximately 50% as basal insulin and 50% as prandial insulin using Humalog. 1

• The acceptable range for total daily insulin in type 1 diabetes is 0.4–1.0 units/kg/day, with 0.5 units/kg/day representing the standard starting point for metabolically stable patients 1, 2
• For a 70 kg adult, this translates to approximately 35 units total daily: 17–18 units as basal insulin (glargine or detemir) once daily, and 17–18 units as Humalog divided among three meals (approximately 6 units per meal) 1, 2
• Higher doses (up to 1.5 units/kg/day) are required during puberty, pregnancy, or acute illness 1, 2

Basal Insulin Component (40–50% of Total Daily Dose)

Administer a long-acting basal insulin analog (insulin glargine or insulin detemir) once daily at bedtime, comprising 40–50% of the total daily insulin dose. 1, 2

• For the 70 kg example above, start with 17–18 units of insulin glargine (Lantus) or detemir (Levemir) once daily 1, 2
• Insulin glargine provides approximately 24 hours of peakless basal coverage when administered at bedtime 1, 3
• Insulin detemir may require twice-daily dosing in some patients with type 1 diabetes if once-daily administration fails to provide adequate 24-hour coverage 1

Basal Insulin Titration Protocol

• Increase basal insulin by 2 units every 3 days if fasting glucose is 140–179 mg/dL 1, 2
• Increase basal insulin by 4 units every 3 days if fasting glucose is ≥180 mg/dL 1, 2
• Target fasting glucose range: 80–130 mg/dL 1, 2
• If unexplained hypoglycemia (glucose <70 mg/dL) occurs, reduce the basal dose by 10–20% immediately 1, 2

Prandial Humalog Component (50–60% of Total Daily Dose)

Administer Humalog (insulin lispro) 0–15 minutes before each of the three main meals, with the total prandial dose comprising 50–60% of the total daily insulin. 1, 2, 4

• For the 70 kg example, divide 17–18 units among three meals: approximately 6 units before breakfast, 6 units before lunch, and 6 units before dinner 1, 2
• Humalog has an onset of action at 0.25–0.5 hours, peaks at 1–3 hours, and has a duration of 3–5 hours 1, 5
• Administer Humalog immediately before eating (0–15 minutes) for optimal postprandial glucose control 1, 2, 4

Prandial Insulin Titration Protocol

• Adjust each meal dose by 1–2 units (or 10–15%) every 3 days based on the 2-hour postprandial glucose reading for that specific meal 1, 2
• Target postprandial glucose: <180 mg/dL 1, 2
• If hypoglycemia occurs after a specific meal, reduce that meal's Humalog dose by 10–20% 1, 2

Carbohydrate-to-Insulin Ratio (CIR) Method

Once stable doses are established, calculate an insulin-to-carbohydrate ratio using the formula: 450 ÷ total daily insulin dose. 2

• For a patient on 35 units total daily insulin: 450 ÷ 35 = approximately 1 unit per 13 grams of carbohydrate 2
• A common starting ratio is 1 unit per 10–15 grams of carbohydrate, adjusted based on postprandial glucose patterns 2
• The CIR often varies by meal, with breakfast typically requiring more insulin per gram of carbohydrate due to counter-regulatory hormones (cortisol, growth hormone) 2

Correction (Supplemental) Insulin Dosing

Use an insulin sensitivity factor (ISF) to calculate correction doses when premeal glucose exceeds target range. 2

• Calculate ISF as: 1500 ÷ total daily insulin dose 2
• For a patient on 35 units total daily: 1500 ÷ 35 = approximately 43 mg/dL per unit (meaning 1 unit of Humalog will lower glucose by ~43 mg/dL) 2
• Correction dose = (Current glucose – Target glucose) ÷ ISF 2
• Simplified correction scale: Add 2 units for premeal glucose >250 mg/dL; add 4 units for glucose >350 mg/dL 2
• Correction insulin must supplement, not replace, scheduled prandial doses 2

Monitoring Requirements

Perform self-monitoring of blood glucose at least 4 times daily: before each meal and at bedtime. 1

• Check fasting glucose daily to guide basal insulin adjustments 1, 2
• Measure premeal glucose before each meal to calculate correction doses 2
• Obtain 2-hour postprandial glucose after each meal to assess prandial insulin adequacy 1, 2
• For intensive management, 6–10 glucose checks per day may be needed (including occasional postprandial, pre-exercise, or when hypoglycemia is suspected) 2
• Measure HbA1c every 3 months to assess overall glycemic control 1, 2

Glycemic Targets

• Fasting/premeal glucose: 80–130 mg/dL 1, 2
• Postprandial glucose (2 hours after meals): <180 mg/dL 1, 2
• HbA1c target: <7.5% for children and adolescents; <7.0% for most adults (individualized based on patient circumstances) 1
• Hypoglycemia alert threshold: <70 mg/dL 2

Hypoglycemia Management Protocol

Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate (4 glucose tablets or 4 oz juice), recheck in 15 minutes, and repeat if needed. 1, 2

• If hypoglycemia occurs without an obvious cause, reduce the implicated insulin dose by 10–20% before the next administration 1, 2
• Patients should carry fast-acting carbohydrates at all times 2
• Recurrent hypoglycemia shifts glycemic thresholds lower, making future episodes harder to detect; scrupulous avoidance of hypoglycemia for 2–3 weeks can reverse hypoglycemia unawareness 2
• Never use protein-rich foods (e.g., nuts) to treat hypoglycemia, as protein can stimulate insulin secretion 2

Critical Safety Considerations

Sliding-scale insulin must never be used as monotherapy in type 1 diabetes, as it can precipitate diabetic ketoacidosis. 2

• Type 1 diabetes requires continuous basal insulin coverage to prevent ketoacidosis, even when not eating 2
• Never administer Humalog at bedtime as a sole correction dose, as this markedly raises the risk of nocturnal hypoglycemia 1, 2
• Never completely discontinue basal insulin in type 1 diabetes, even during illness or when NPO, to prevent diabetic ketoacidosis 2

Special Situations

Sick Day Management

• Continue insulin even if oral intake is limited 2
• Check glucose every 4 hours during illness 2
• Check urine or blood ketones immediately if glucose >250 mg/dL with nausea, vomiting, abdominal pain, or altered mental status 2
• Maintain adequate hydration 2

Exercise Adjustments

• If moderate-to-vigorous physical activity occurs within 1–2 hours of a mealtime insulin dose, reduce the Humalog dose for that meal to lower hypoglycemia risk 2
• Regular physical activity (at least 150 minutes weekly of moderate-intensity exercise) improves insulin sensitivity and may reduce total insulin requirements 2

Honeymoon Phase

• Patients in the honeymoon phase with residual beta-cell function may require lower doses of 0.2–0.6 units/kg/day 2
• Doses should be adjusted based on glucose monitoring patterns rather than fixed weight-based calculations during this period 2

Patient Education Essentials

Comprehensive diabetes self-management education must cover insulin injection technique, glucose monitoring, hypoglycemia recognition/treatment, carbohydrate counting, and sick-day management. 2

• Proper insulin injection technique and site rotation to prevent lipohypertrophy 1, 2
• Recognition and treatment of hypoglycemia (symptoms, <70 mg/dL threshold, 15-gram carbohydrate rule) 1, 2
• Carbohydrate counting skills to match Humalog doses to food intake 2
• Insulin storage and handling (refrigerate unopened vials; in-use vials can be kept at room temperature) 2
• "Sick day" management rules: continue insulin, check glucose every 4 hours, maintain hydration, check ketones if glucose >250 mg/dL 2

Expected Clinical Outcomes

• With properly implemented basal-bolus therapy using Humalog and a long-acting basal insulin, approximately 68% of patients achieve mean glucose <140 mg/dL, compared with only 38% using inadequate regimens 2, 6
• HbA1c reductions of 2–3% from baseline are achievable within 3–6 months with intensive insulin titration 2
• Basal-bolus therapy with insulin glargine plus Humalog provides similar or better glycemic control and less nocturnal hypoglycemia compared to regimens using human insulin as the basal and/or prandial component 6
• Properly executed basal-bolus regimens do not increase overall hypoglycemia incidence compared with inadequate approaches when titrated according to protocol 2, 6

Common Pitfalls to Avoid

• Do not delay insulin dose adjustments when glucose patterns indicate inadequate coverage; 75% of hospitalized patients with hypoglycemia receive no insulin dose adjustment before the next dose 2
• Do not rely solely on correction doses without adjusting scheduled basal and prandial insulin when glucose remains consistently out of target 2
• Do not use Humalog after meals in patients with predictable eating habits, as premeal dosing results in lower postprandial glucose values 1
• Do not assume the same Humalog dose is appropriate for all meals; breakfast often requires more insulin per gram of carbohydrate due to dawn phenomenon 2