What is the recommended dosing and management strategy for glargine (insulin glargine) in patients with diabetes mellitus?

Insulin Glargine (Lantus) Dosing and Management in Diabetes Mellitus

Insulin glargine should be initiated at 10 units or 0.1-0.2 units/kg once daily at bedtime, with dose adjustments based on fasting blood glucose levels, as part of a comprehensive diabetes management strategy. 1

Initial Dosing Recommendations

Type 2 Diabetes

• Starting dose:
  • 10 units once daily at bedtime OR
  • 0.1-0.2 units/kg once daily 1, 2
• For insulin-naïve patients: Start at 0.1-0.2 units/kg once daily in the evening or 10 units once or twice daily 2
• For patients switching from other basal insulins: Convert on a unit-to-unit basis, then adjust as needed 2
• Timing: Administer with evening meal, at bedtime, or at a consistent time daily 2

Type 1 Diabetes

• Starting dose: 0.2-0.4 units/kg/day total insulin with approximately 50% as basal insulin glargine 1
• Must be used with: Rapid-acting insulin (insulin aspart, lispro, or glulisine) before meals for prandial coverage 1
• Administration: Once daily at bedtime, though some patients may benefit from twice-daily dosing 3

Dose Adjustment Algorithm

Basal Insulin Titration

• Adjust dose every 3 days based on fasting blood glucose patterns 4
• If fasting glucose >130 mg/dL: Increase by 2 units
• If fasting glucose 110-130 mg/dL: Increase by 1 unit
• If hypoglycemia occurs: Reduce by 2-4 units or 10-20%

Special Considerations

• Elderly patients: Start at lower end of dosing range (0.1 units/kg) and titrate more cautiously 1
• Renal impairment: Lower doses may be required due to decreased insulin clearance 4
• Obese, insulin-resistant patients: May require higher doses or split dosing (twice daily) due to large volume requirements 3

Monitoring and Follow-up

• Blood glucose monitoring: 4 or more tests daily, including fasting and postprandial measurements 1
• Target fasting glucose: 80-130 mg/dL 4
• HbA1c monitoring: Every 3-6 months 4
• Dose titration: Based on self-monitoring blood glucose (SMBG) levels 1

Combination Therapy Considerations

Type 2 Diabetes

• First-line combination: Maintain metformin when starting glargine 1
• When to add prandial insulin: When basal insulin has been optimized but HbA1c remains above target 1
• Medication adjustments:
  • Sulfonylureas, DPP-4 inhibitors, and GLP-1 receptor agonists are typically discontinued when more complex insulin regimens are used 1
  • Thiazolidinediones or SGLT2 inhibitors may be continued to reduce total daily insulin dose 1

Type 1 Diabetes

• Always combine with: Rapid-acting insulin analogs before meals 1
• Basal-bolus ratio: Typically 50% basal, 50% bolus, adjusted based on individual needs 1

Common Pitfalls and Practical Tips

• Do not mix glargine with other insulins in the same syringe as it may alter the pharmacokinetic profile 2, 5
• Injection site rotation is essential to prevent lipohypertrophy 4
• Hypoglycemia risk is highest in the first four weeks after switching to insulin glargine 6
• Nocturnal hypoglycemia is less common with glargine compared to NPH insulin 7, 8
• For patients with erratic eating patterns: Consider more flexible dosing with glargine, which can be administered at any consistent time of day 3
• For patients with persistent hyperglycemia despite optimized basal insulin: Add prandial insulin rather than increasing basal dose beyond appropriate levels 1

By following these dosing and management guidelines, patients with diabetes can achieve optimal glycemic control while minimizing the risk of hypoglycemia and other complications.