What are the typical dosing regimens for basal and bolus insulin?

Typical Dosing Regimens for Basal and Bolus Insulin

Basal Insulin Dosing

For insulin-naive patients with type 2 diabetes, start with 10 units once daily or 0.1-0.2 units/kg body weight, administered at the same time each day. 1, 2

Initial Dosing by Clinical Scenario

Type 2 Diabetes - Standard Initiation:

• Start with 10 units once daily OR 0.1-0.2 units/kg/day for patients with moderate hyperglycemia 1, 2, 3
• Continue metformin (unless contraindicated) and possibly one additional non-insulin agent 1, 2
• Administer at the same time daily (bedtime is most common) 2, 4

Type 2 Diabetes - Severe Hyperglycemia:

• For HbA1c ≥9% or blood glucose ≥300-350 mg/dL, consider higher starting doses of 0.3-0.5 units/kg/day as total daily dose, split between basal and prandial insulin 1, 2, 5
• For HbA1c 10-12% with symptomatic or catabolic features, initiate basal-bolus regimen immediately 1, 2

Type 1 Diabetes:

• Total daily insulin requirement: 0.4-1.0 units/kg/day, with 0.5 units/kg/day typical for metabolically stable patients 2, 6
• Divide approximately 50% as basal insulin and 50% as prandial insulin 2, 5
• Higher doses needed during puberty, pregnancy, and acute illness (may exceed 1.0 units/kg/day) 2

Basal Insulin Titration Algorithm

Increase basal insulin systematically based on fasting glucose levels: 2

• If fasting glucose 140-179 mg/dL: increase by 2 units every 3 days
• If fasting glucose ≥180 mg/dL: increase by 4 units every 3 days
• Target fasting plasma glucose: 80-130 mg/dL 1, 2
• If hypoglycemia occurs without clear cause, reduce dose by 10-20% immediately 2, 5

Critical Threshold: When to Stop Escalating Basal Insulin

When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin rather than continuing to escalate basal insulin alone. 1, 2

Clinical signs of "overbasalization" include: 2

• Basal insulin dose >0.5 units/kg/day
• Bedtime-to-morning glucose differential ≥50 mg/dL
• Hypoglycemia episodes
• High glucose variability despite adequate fasting glucose control

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Bolus (Prandial) Insulin Dosing

When adding prandial insulin, start with 4 units of rapid-acting insulin before the largest meal OR 10% of the current basal dose. 1, 2

Indications for Adding Prandial Insulin

Add prandial insulin when: 1, 2

• Basal insulin has been optimized (fasting glucose 80-130 mg/dL) but HbA1c remains above target after 3-6 months
• Basal insulin dose approaches 0.5-1.0 units/kg/day without achieving glycemic goals
• Significant postprandial glucose excursions persist despite adequate fasting control

Prandial Insulin Initiation Strategy

Stepwise Approach: 2, 5

• Start with one prandial dose before the largest meal (typically dinner)
• Use 4 units of rapid-acting insulin OR 10% of basal dose
• Progress to two meals, then three meals as needed based on glucose patterns
• Titrate each dose by 1-2 units or 10-15% every 3 days based on postprandial glucose readings

Rapid-Acting Insulin Options: 1, 6

• Insulin lispro, aspart, or glulisine
• Administer 0-15 minutes before meals
• Preferred over regular insulin due to better postprandial control and lower hypoglycemia risk

Basal-Bolus Regimen for Severe Hyperglycemia

For patients requiring immediate basal-bolus therapy (HbA1c ≥10-12% with symptoms): 2, 5

• Calculate total daily dose: 0.3-0.5 units/kg/day
• Give 50% as basal insulin once daily
• Give 50% as prandial insulin, divided among three meals
• For high-risk patients (elderly >65 years, renal failure, poor oral intake), use lower doses of 0.1-0.25 units/kg/day 2, 5

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Special Populations

Pediatric Type 2 Diabetes: 1

• For youth with marked hyperglycemia (blood glucose ≥250 mg/dL, HbA1c ≥8.5%) without acidosis, start basal insulin while initiating metformin
• Patients on basal insulin up to 1.5 units/kg/day who don't meet targets should transition to multiple daily injections with basal and premeal bolus insulin

Hospitalized Patients: 2, 7

• For insulin-naive or low-dose patients: 0.3-0.5 units/kg/day total daily dose, with half as basal insulin
• For patients on high-dose home insulin (≥0.6 units/kg/day): reduce total daily dose by 20% to prevent hypoglycemia
• Continuous IV insulin infusion preferred for critically ill patients

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Common Pitfalls to Avoid

Do not delay insulin therapy in patients not achieving glycemic goals - this is a critical error that prolongs poor glycemic control 1, 2

Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia - this leads to overbasalization with increased hypoglycemia risk and suboptimal control 2

Do not discontinue metformin when starting insulin - metformin should be continued unless contraindicated, as it reduces insulin requirements and provides complementary glucose-lowering effects 1, 2

Do not rely solely on sliding scale insulin - scheduled basal-bolus regimens are superior to correction insulin alone 2, 7

Do not wait longer than 3 days between basal insulin adjustments in stable patients - this unnecessarily prolongs time to achieve glycemic targets 2

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Monitoring Requirements

Daily fasting blood glucose monitoring is essential during titration 1, 2

Assess insulin adequacy at every clinical visit, looking for signs of overbasalization 2

Check HbA1c every 3 months during intensive titration 1, 2

Adjust both basal and prandial insulin based on self-monitoring of blood glucose levels - fasting glucose guides basal insulin, while pre-meal and postprandial glucose guide prandial insulin 1, 2