What is the recommended usage and dosage of insulin glargine (insulin glargine) for patients with type 1 or type 2 diabetes?

Insulin Glargine Usage and Dosage Guidelines for Diabetes Management

Human insulin glargine should be used as the primary basal insulin for patients with type 1 diabetes, while in type 2 diabetes it should be initiated at 0.2 units/kg or up to 10 units once daily when oral medications fail to achieve glycemic control. 1

Dosing Recommendations

Type 1 Diabetes

• Initial dose: Approximately one-third of total daily insulin requirements as basal insulin 1
• Remaining insulin requirements should be covered with short-acting insulin before meals 1
• Total daily insulin requirements typically range from 0.4 to 1.0 units/kg/day 2
• Generally, 50% of total daily insulin is given as basal insulin and 50% as prandial insulin 2, 3

Type 2 Diabetes

• Starting dose: 0.2 units/kg or up to 10 units once daily 1
• When adding to oral agents: Start with 10 units or 0.1-0.2 units/kg once daily 2
• Titration: Adjust dose every 3 days based on fasting blood glucose levels 3
  • FBG ≥180 mg/dL: Increase by 6-8 units
  • FBG 140-179 mg/dL: Increase by 4 units
  • FBG 120-139 mg/dL: Increase by 2 units
  • FBG <100 mg/dL: Decrease by 2-4 units
  • Any hypoglycemia (<70 mg/dL): Decrease by 10-20%

Administration Guidelines

• Administer subcutaneously once daily at the same time every day 1
• Common injection sites: abdominal area, thigh, or deltoid 1
• Rotate injection sites within the same region to reduce risk of lipodystrophy 1
• Do not administer intravenously or via insulin pump 1
• Do not dilute or mix with any other insulin or solution 1

Switching from Other Insulin Therapies

• From NPH once daily: Use same dose of insulin glargine 1
• From NPH twice daily: Use 80% of total NPH dose as starting insulin glargine dose 1
• From other long-acting insulins: Adjust dosage based on previous insulin requirements 1

Advantages of Insulin Glargine

Clinical Benefits

• Provides relatively constant basal insulin levels with no pronounced peak 4
• Longer duration of action (approximately 24 hours) compared to NPH insulin 5
• Lower risk of nocturnal hypoglycemia compared to NPH insulin 4, 5, 6
• Similar or better glycemic control compared to NPH insulin 4, 5

Special Considerations

• Elderly patients or those with renal failure should start with lower doses (0.1 units/kg/day) to minimize hypoglycemia risk 3
• Increase frequency of blood glucose monitoring during regimen changes 1
• For patients with type 1 diabetes, insulin glargine must be used with short-acting insulin 1

Monitoring and Dose Adjustment

• Check blood glucose at least 4 times daily (fasting, before meals, and bedtime) 3
• Evaluate for signs of overbasalization (nocturnal hypoglycemia, large drops between bedtime and morning glucose) 3
• If fasting glucose is at target but HbA1c remains elevated, consider increasing mealtime insulin 3
• If nocturnal hypoglycemia occurs, reduce evening basal insulin dose 3

Evidence-Based Outcomes

• In patients with type 1 diabetes, insulin glargine achieves equivalent glycemic control to NPH insulin with lower fasting blood glucose levels 4
• In patients with type 2 diabetes, insulin glargine provides at least equivalent glycemic control with significantly fewer episodes of nocturnal hypoglycemia 6
• The WHO guidelines recommend human insulin as first-line treatment for patients with type 2 diabetes who do not achieve glycemic control with metformin and/or sulfonylurea 2
• Long-acting insulin analogues like glargine should be considered for patients who experience frequent severe hypoglycemia with human insulin 2

By following these guidelines for insulin glargine administration, clinicians can optimize glycemic control while minimizing the risk of hypoglycemia in patients with both type 1 and type 2 diabetes.