What are the guidelines for adjusting insulin doses in patients with diabetes?

Insulin Dose Adjustment Guidelines

For basal insulin adjustment, increase the dose by 2 units every 3 days until fasting plasma glucose reaches target (90-150 mg/dL) without hypoglycemia, and for prandial insulin, adjust doses based on the insulin-to-carbohydrate ratio and postprandial glucose monitoring. 1, 2

Basal Insulin Titration

Starting and Adjusting Basal Insulin:

• For insulin-naive patients, initiate basal insulin at 10 units per day OR 0.1-0.2 units/kg per day 1
• For patients with type 2 diabetes inadequately controlled on oral agents, start at 0.1-0.2 units/kg once daily 3
• Increase by 2 units every 3 days to reach fasting plasma glucose target without hypoglycemia 1, 2
• Set fasting glucose target of 90-150 mg/dL (5.0-8.3 mmol/L) for most patients 1
• If 50% of fasting values exceed goal over one week: increase dose by 2 units 1
• If more than 2 fasting values per week are <80 mg/dL: decrease dose by 2 units 1

Critical Pitfall to Avoid:

• Do not increase basal insulin by more than 2 units at a time, as aggressive dose increases lead to hypoglycemia 2
• For hypoglycemia without clear cause, lower the dose by 10-20% 1

Prandial (Bolus) Insulin Adjustment

Initiating Prandial Insulin:

• Start with 4 units per dose OR 10% of basal dose with the largest meal or meal with greatest postprandial glucose excursion 1
• When adding prandial insulin, reduce basal dose by 4 units or 10% 1

Titration Strategy:

• Increase dose by 1-2 units or 10-15% twice weekly based on postprandial glucose 1
• Monitor blood glucose 2-3 hours after meals to verify adequate coverage 4
• For hypoglycemia without clear cause, lower corresponding dose by 10-20% 1

Insulin-to-Carbohydrate Ratio Management

Understanding the Ratio:

• The insulin-to-carbohydrate ratio (commonly 1:10) means 1 unit of insulin covers 10 grams of carbohydrate 4
• Calculate bolus dose: (grams of carbohydrate consumed) ÷ (carbohydrate per unit ratio) 4
• The ratio remains constant, but total insulin dose changes proportionally to carbohydrate intake 4

Adjusting for Carbohydrate Changes:

• A 50% reduction in carbohydrates requires a 50% reduction in prandial insulin dose 4
• If postprandial glucose consistently exceeds target, adjust the ratio to be more aggressive (e.g., from 1:10 to 1:8) 4
• If hypoglycemia occurs, adjust to be less aggressive (e.g., from 1:10 to 1:12) 4

Total Daily Dose Calculations

For Basal-Bolus Regimens:

• Total daily dose for insulin-naive patients: 0.3-0.5 units/kg 1
• Allocate 50% to basal insulin (given 1-2 times daily) and 50% to prandial insulin (divided before three meals) 1
• Use lower doses (0.3 units/kg) for patients at higher hypoglycemia risk: age >65 years, renal failure, or poor oral intake 1

For Patients Already on Insulin:

• If taking ≥0.6 units/kg per day at home, reduce total daily dose by 20% during hospitalization to prevent hypoglycemia 1
• Basal insulin typically comprises 48% of total daily dose 5

Warning About Overbasalization:

• Assess for overbasalization if basal dose exceeds 0.5 units/kg per day, if there is elevated bedtime-to-morning glucose differential, or if hypoglycemia or high variability occurs 1

Correction (Sliding Scale) Insulin

Appropriate Use:

• Correction insulin should be added to carbohydrate coverage based on pre-meal glucose if above target 4
• The correction dose (insulin sensitivity factor) remains unchanged when carbohydrate intake varies 4
• Do not use sliding scale insulin alone as the primary regimen in patients with type 1 or type 2 diabetes requiring insulin 1
• Sliding scale may be appropriate only for patients without diabetes who have mild stress hyperglycemia 1

Simplified Correction Approach (for older adults adjusting complex regimens):

• For premeal glucose >250 mg/dL: give 2 units of rapid-acting insulin 1
• For premeal glucose >350 mg/dL: give 4 units of rapid-acting insulin 1
• Stop sliding scale when not needed daily 1

Monitoring and Reassessment

Frequency of Adjustments:

• Reassess and modify treatment regularly every 3-6 months 1
• Adjust insulin dose and/or add glucose-lowering agents every 2 weeks based on finger-stick testing 1
• Monitor fasting blood glucose daily to assess basal insulin effect 2

Glucose Targets:

• Fasting and premeal goal: 80-130 mg/dL 6
• Two-hour postprandial goal: <180 mg/dL 6
• For older adults or those with complex health status, target 90-150 mg/dL before meals 1

Special Considerations for Simplifying Complex Regimens

For Older Adults on Complex Insulin Plans:

• Change basal insulin timing from bedtime to morning 1
• If on premixed insulin, use 70% of total dose as basal only in the morning 1
• If prandial insulin ≤10 units per dose: discontinue and add noninsulin agent 1
• If prandial insulin >10 units per dose: decrease by 50% and add noninsulin agent 1
• Do not use rapid- or short-acting insulin at bedtime 1

Hypoglycemia Prevention

Key Safety Measures:

• Patients should carry at least 15 grams of fast-acting carbohydrate for hypoglycemia treatment 4
• If recurrent hypoglycemia occurs despite correct calculations, reduce insulin dose by 10-20% and consult diabetes care team 4
• Patients with severe hypoglycemia requiring assistance may benefit from short-term relaxation of glycemic targets 6