What insulin sliding‑scale correction regimen should be used for a pregnant woman with gestational diabetes who is taking premixed insulin 70/30 (18 U before breakfast and 12 U before supper)?

Correction Insulin Sliding‑Scale Regimen for Pregnant Women with GDM on Premixed Insulin 70/30

For pregnant women with gestational diabetes on premixed insulin 70/30 (18 U pre‑breakfast, 12 U pre‑supper), correction insulin should be added using rapid‑acting insulin analogs (lispro or aspart) at 1–2 units for pre‑meal glucose >120 mg/dL, with dose adjustments every 1–2 days based on 1‑hour postprandial readings targeting <120 mg/dL. 1, 2

Pregnancy‑Specific Glucose Targets

• Fasting glucose: <95 mg/dL 1
• 1‑hour postprandial glucose: <120 mg/dL 1, 2
• These stricter targets in pregnancy necessitate more aggressive correction than non‑pregnant protocols 1

Recommended Correction Insulin Protocol

Choice of Insulin

• Use rapid‑acting insulin analogs (lispro or aspart) for correction doses, as they provide faster onset and shorter duration, minimizing hypoglycemia risk between meals 1, 2
• Insulin lispro has been demonstrated safe and effective in GDM, with minimal episodes of postprandial hyperglycemia and hypoglycemia 2

Correction Dosing Algorithm

• Pre‑meal glucose 120–140 mg/dL: Add 1 unit rapid‑acting insulin 1
• Pre‑meal glucose 141–160 mg/dL: Add 2 units rapid‑acting insulin 1
• Pre‑meal glucose >160 mg/dL: Add 3 units rapid‑acting insulin and contact provider 1

Timing of Administration

• Administer correction insulin 0–15 minutes before meals together with the scheduled premixed insulin 70/30 dose 1, 2
• For insulin lispro specifically, administration immediately before meals is safe and effective in pregnancy 2

Titration Strategy for Premixed Insulin 70/30

Basal Insulin Adjustment (Morning Dose)

• If fasting glucose >95 mg/dL on ≥2 consecutive days, increase the evening premixed insulin dose by 2 units 1, 3
• The evening dose primarily provides overnight basal coverage affecting fasting glucose 1

Prandial Insulin Adjustment

• If 1‑hour post‑breakfast glucose >120 mg/dL on ≥2 consecutive days, increase the morning premixed insulin dose by 2 units 1, 3
• If 1‑hour post‑supper glucose >120 mg/dL on ≥2 consecutive days, increase the evening premixed insulin dose by 2 units 1, 3

Frequency of Adjustments

• Insulin requirements in GDM increase significantly until approximately 30 weeks' gestation, then stabilize 3
• Adjust doses every 1–2 days during the initial treatment period (first 7–10 days) until target glucose range is achieved 3
• After stabilization, reassess and adjust every 3–7 days based on glucose patterns 1, 3

Monitoring Requirements

Blood Glucose Testing Frequency

• Fasting glucose daily 1, 3
• 1‑hour postprandial glucose after each meal (breakfast, lunch, supper) 1, 2, 3
• Minimum 4 checks daily (fasting + 3 postprandial) 1, 3
• During initial titration, 6–7 checks daily may be needed 3

Pattern Recognition

• Review glucose logs every 1–2 days during active titration 1, 3
• Look for consistent patterns over 2–3 days before making dose adjustments 1

Critical Threshold Considerations

When to Transition from Premixed to Basal‑Bolus

• If total daily premixed insulin exceeds 0.5 units/kg/day without achieving targets, consider transitioning to a basal‑bolus regimen with separate basal insulin (NPH or detemir) and rapid‑acting insulin at each meal 1
• Premixed insulin formulations provide less flexibility for dose adjustments compared to basal‑bolus regimens 4, 1

Insulin Requirements Throughout Pregnancy

• Expect insulin requirements to increase significantly from initiation through 30 weeks' gestation 3
• Correlation between insulin dose at 24 and 32 weeks is moderate (r=0.58), but correlation between 32 and 39 weeks is very strong (r=0.99), indicating stabilization in the third trimester 3

Hypoglycemia Management in Pregnancy

Treatment Protocol

• Treat glucose <70 mg/dL immediately with 15 g fast‑acting carbohydrate 4
• Recheck glucose in 15 minutes and repeat treatment if needed 4
• If hypoglycemia occurs without clear cause, reduce the implicated insulin dose by 10–20% before the next administration 4, 1

Prevention Strategies

• Rapid‑acting insulin analogs (lispro, aspart) reduce hypoglycemia frequency compared to regular human insulin due to their shorter duration of action 2, 5
• Never administer correction insulin at bedtime as a sole dose, as this markedly increases nocturnal hypoglycemia risk 4, 6

Alternative Insulin Regimens if Premixed 70/30 Is Inadequate

Biphasic Aspart 30 (NovoLog Mix 70/30)

• Premixed insulin aspart 30 (BIAsp 30) is equally safe and effective as premixed human insulin 30/70 in GDM 7
• BIAsp 30 offers the convenience of meal‑time dosing (0–15 minutes before meals) versus 30 minutes before meals for human premixed insulin 7
• Fetal outcomes are comparable between BIAsp 30 and human premixed insulin 30/70 7

Basal‑Bolus Regimen

• If premixed insulin fails to achieve targets, transition to NPH insulin twice daily (providing basal coverage) plus rapid‑acting insulin (lispro or aspart) before each meal 1
• This regimen provides greater flexibility for dose adjustments based on variable meal sizes and timing 1

Patient Education Essentials

Self‑Management Skills

• Teach patients to recognize glucose patterns and understand how their glucose responds to insulin, meal content/portion size, and physical activity 1
• Empower patients to make minor dose adjustments (1–2 units) based on pre‑established algorithms after initial stabilization 1

Injection Technique

• Proper insulin injection technique and site rotation to prevent lipohypertrophy 6
• Administer premixed insulin 70/30 30 minutes before meals for optimal postprandial control 7
• Administer rapid‑acting correction insulin 0–15 minutes before meals 1, 2

Lifestyle Factors

• Emphasize the impact of meal timing, portion size, carbohydrate content, physical activity, sleep cycles, and stress on glucose control 1
• Individualize insulin regimens based on cultural and lifestyle behaviors affecting meal, activity, and occupational schedules 1

Common Pitfalls to Avoid

• Do not use sliding‑scale correction insulin as monotherapy without scheduled basal and prandial insulin; this approach is condemned by major diabetes guidelines and leads to dangerous glucose fluctuations 4, 6
• Do not delay insulin dose adjustments when glucose consistently exceeds targets; early aggressive titration in the first 7–10 days is critical to achieving control 3
• Do not use regular human insulin for correction doses in pregnancy; rapid‑acting analogs (lispro, aspart) are preferred for their faster onset and shorter duration, reducing hypoglycemia risk 1, 2
• Do not continue escalating premixed insulin doses beyond 0.5 units/kg/day without considering transition to a basal‑bolus regimen for greater flexibility 1
• Do not administer correction insulin at bedtime as a sole dose, as this markedly increases nocturnal hypoglycemia risk 4, 6

Expected Clinical Outcomes

• With appropriate insulin titration using correction doses, minimal episodes of postprandial hyperglycemia (1‑hour glucose >120 mg/dL) and minimal incidence of hypoglycemia should be achieved 2
• Insulin lispro has been shown to be safe and effective in GDM, with no congenital abnormalities or significant postpartum complications in clinical studies 2
• Fetal outcomes (macrosomia rates, birth weight >90th percentile) are comparable between premixed human insulin and premixed insulin analogs when glucose targets are achieved 7