How do I adjust my patient's insulin regimen?

Adjusting Insulin Regimens: A Practical Approach

The most effective strategy for insulin adjustment depends on your patient's current regimen, glycemic patterns, and clinical context—titrate basal insulin by 2 units every 3 days based on fasting glucose, add prandial insulin when postprandial glucose remains elevated despite adequate basal control, and simplify complex regimens in older adults to reduce hypoglycemia risk. 1, 2

Initial Assessment and Monitoring Framework

Before adjusting insulin, establish:

• Current insulin types and doses (basal, prandial, or premixed) 1
• Glucose monitoring patterns: fasting, pre-meal, and 2-3 hours post-meal values 3
• Patient characteristics: age, renal function (eGFR), cognitive status, and hypoglycemia history 1
• Glycemic targets: individualize based on health status (healthy older adults: A1C <7.0-7.5%; complex/intermediate health: <8.0%) 1

Basal Insulin Titration

Starting Basal Insulin

• Initial dose: 10 units daily OR 0.1-0.2 units/kg body weight 1, 2, 4
• Administration: once daily at the same time (can be morning or bedtime) 1, 4
• Target fasting glucose: 90-150 mg/dL (5.0-8.3 mmol/L) 1

Systematic Titration Algorithm

• Increase by 2 units every 3 days if fasting glucose remains above target 2
• Alternative approach: If ≥50% of fasting values exceed goal over one week, increase by 2 units 1
• Decrease by 2 units if >2 fasting values per week are <80 mg/dL (4.4 mmol/L) 1
• For hypoglycemia: reduce dose by 10-20% if no clear precipitating cause identified 2

Recognizing Overbasalization

Stop increasing basal insulin when you observe: 2

• Controlled fasting glucose but elevated postprandial values
• Large bedtime-to-morning glucose differential
• Increasing hypoglycemia episodes
• High glucose variability despite dose escalation

When overbasalization occurs, add GLP-1 receptor agonist or prandial insulin rather than continuing to increase basal doses. 2

Adding or Adjusting Prandial Insulin

When to Add Prandial Coverage

• Basal insulin optimized (fasting glucose at goal) but A1C remains above target 1
• Postprandial glucose excursions persist despite adequate basal control 1, 2

Prandial Insulin Dosing

• Use insulin-to-carbohydrate ratios: typically 1:10 (1 unit covers 10 grams carbohydrate) 3
• Calculate dose: (grams of carbohydrate consumed) ÷ (carbohydrate-per-unit ratio) 3
• Add correction dose if pre-meal glucose is elevated, using insulin sensitivity factor 3
• Timing: administer rapid-acting analogs (lispro, aspart, glulisine) immediately before meals 1

Adjusting for Carbohydrate Changes

• Proportional reduction: If carbohydrate intake decreases by 50%, reduce prandial insulin by 50% 3
• The insulin-to-carbohydrate ratio stays constant; only the total dose changes 3
• Monitor post-meal glucose 2-3 hours after eating to verify adequacy 3
• If recurrent hypoglycemia occurs, adjust ratio to be less aggressive (e.g., 1:10 to 1:12) 3

Simplifying Complex Regimens (Especially for Older Adults)

For Patients on Basal + Prandial Insulin

Basal insulin adjustments: 1

• Change timing from bedtime to morning administration
• Titrate based on fasting glucose over one week
• Target: 90-150 mg/dL fasting

Prandial insulin simplification: 1

• If prandial dose ≤10 units/meal: Discontinue prandial insulin and add non-insulin agents (metformin if eGFR ≥45, or GLP-1 RA/SGLT2i/DPP-4i if eGFR <45 or metformin not tolerated)
• If prandial dose >10 units/meal: Decrease by 50% and add non-insulin agents, then titrate prandial doses down progressively

For Patients on Premixed Insulin

• Convert to basal-only: Use 70% of total daily premixed dose as basal insulin in the morning 1
• Add non-insulin agents as above
• Titrate based on fasting and pre-meal glucose values

Simplified Sliding Scale (Temporary Use Only)

While adjusting regimens, use sparingly: 1

• Pre-meal glucose >250 mg/dL: give 2 units rapid-acting insulin
• Pre-meal glucose >350 mg/dL: give 4 units rapid-acting insulin
• Discontinue sliding scale when not needed daily

When Adding Prandial to Existing Basal Insulin

Reduce basal insulin by 4 units or 10% when adding prandial coverage if A1C <8% to prevent hypoglycemia 2

Critical Safety Considerations

Hypoglycemia Prevention

• Never use rapid- or short-acting insulin at bedtime 1
• Increase glucose monitoring frequency during any regimen changes 4
• Patients should carry ≥15 grams fast-acting carbohydrate at all times 3
• For recurrent hypoglycemia despite correct calculations, reduce insulin by 10-20% 3, 2

Medication Interactions and Adjustments

• Continue metformin when initiating basal insulin (if eGFR ≥30 mL/min/1.73 m²) 1
• Consider discontinuing sulfonylureas, DPP-4 inhibitors when advancing to complex insulin regimens 1
• GLP-1 receptor agonists can be combined with basal insulin to address postprandial glucose without increasing hypoglycemia risk 1, 2

Administration Principles

• Rotate injection sites within same region (abdomen, thigh, deltoid) to prevent lipodystrophy 4
• Do not mix insulin glargine with other insulins due to low pH 1, 4
• Administer at same time daily for consistency 4

Common Pitfalls to Avoid

1. Continuing to increase basal insulin indefinitely when postprandial glucose is the problem—recognize overbasalization 2
2. Using sliding scale as primary therapy rather than scheduled basal-bolus regimens 5
3. Failing to reduce insulin when adding other agents or when carbohydrate intake decreases 3, 2
4. Not individualizing targets for older adults or those with complex health status 1
5. Changing insulin types without medical supervision and increased monitoring 1, 4

Monitoring Schedule

• Every 2 weeks: Adjust insulin doses and/or add glucose-lowering agents based on pre-meal glucose patterns 1
• Goal: If 50% of pre-meal values over 2 weeks exceed target, increase dose or add another agent 1
• Assess at every visit: Review glucose logs, insulin adequacy, and need for regimen adjustment 2