What is the recommended dosage of insulin glargine (insulin glargine) for a patient with type 1 or type 2 diabetes mellitus (DM)?

Insulin Glargine Dosing for Injection

Initial Dosing Recommendations

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

Type 1 Diabetes

• The recommended starting dose is approximately one-third of total daily insulin requirements, with short-acting premeal insulin providing the remainder 2
• Total daily insulin typically ranges from 0.4-1.0 units/kg/day, with 0.5 units/kg/day being standard for metabolically stable patients 1, 3
• Distribute as 40-60% basal insulin (glargine) and 40-60% prandial insulin 1, 3
• Patients presenting with diabetic ketoacidosis require higher weight-based dosing initially 3

Type 2 Diabetes

• Start with 10 units once daily for most patients 1, 2
• Alternative weight-based approach: 0.1-0.2 units/kg/day 1, 2
• For severe hyperglycemia (A1C ≥9%, glucose ≥300-350 mg/dL), consider higher starting doses of 0.3-0.5 units/kg/day as total daily insulin using basal-bolus regimen from onset 1
• Continue metformin unless contraindicated when initiating insulin glargine 1

Administration Guidelines

Administer insulin glargine subcutaneously once daily at any time of day, but at the same time every day. 2

• Inject into the abdominal area, thigh, or deltoid 2
• Rotate injection sites within the same region to reduce risk of lipodystrophy 2
• Do NOT administer intravenously, via insulin pump, or mix with other insulins 2
• The solution must be clear and colorless with no visible particles 2

Dose Titration Protocol

Increase insulin glargine by 2-4 units every 3 days until fasting blood glucose reaches 80-130 mg/dL. 1

Specific Titration Algorithm

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

Daily Monitoring Requirements

• Check fasting blood glucose every morning during titration phase 1
• Increase frequency of blood glucose monitoring during any insulin regimen changes 2

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 or GLP-1 receptor agonist rather than continuing to escalate basal insulin alone. 1

Signs of "Overbasalization"

• Basal insulin dose >0.5 units/kg/day 1
• Bedtime-to-morning glucose differential ≥50 mg/dL 1
• Episodes of hypoglycemia 1
• High glucose variability throughout the day 1

Adding Prandial Insulin

• Start with 4 units of rapid-acting insulin before the largest meal 1
• Alternative: use 10% of current basal dose 1
• Titrate prandial insulin by 1-2 units or 10-15% every 3 days based on postprandial glucose 1

Special Populations and Dose Adjustments

High-Risk Patients

• Elderly (>65 years), renal failure, poor oral intake: start with lower doses of 0.1-0.25 units/kg/day 1
• Hospitalized patients on high-dose home insulin (≥0.6 units/kg/day): reduce total daily dose by 20% upon admission 1

Increased Insulin Requirements

• Puberty: may require up to 1.5 units/kg/day 4, 3
• Pregnancy, medical illness, steroids: require higher doses 1, 3

Renal Impairment

• CKD Stage 5 with type 2 diabetes: reduce total daily insulin by 50% 1
• CKD Stage 5 with type 1 diabetes: reduce total daily insulin by 35-40% 1

Switching from Other Insulins

From NPH Insulin

• Once-daily NPH to once-daily glargine: use the same dose 2
• Twice-daily NPH to once-daily glargine: use 80% of total NPH dose 2

From Toujeo (U-300 Glargine)

• Toujeo to Lantus (U-100 glargine): use 80% of Toujeo dose 2

Twice-Daily Dosing Considerations

Consider twice-daily glargine dosing when once-daily administration fails to provide 24-hour coverage, particularly in type 1 diabetes with high glycemic variability. 4, 5

• Indicated for inadequate 24-hour coverage with once-daily dosing 4
• Useful for persistent nocturnal hypoglycemia with morning hyperglycemia 4
• Allows independent titration of morning and evening doses 4

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications 1
• Never discontinue metformin when starting insulin unless contraindicated 1
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia 1
• Never use sliding scale insulin as monotherapy—always use scheduled basal-bolus regimens 1
• Never give rapid-acting insulin at bedtime to avoid nocturnal hypoglycemia 1

Hypoglycemia Management

Treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate, recheck in 15 minutes, and repeat if needed. 1

• All insulin-requiring patients should carry at least 15g carbohydrate 6
• If hypoglycemia occurs, determine the cause and reduce dose by 10-20% 1

Product-Specific Information

Available Formulations

• 10 mL multiple-dose vial (100 units/mL) 2
• 3 mL SoloStar prefilled pen (100 units/mL), dials in 1-unit increments 2

Concentrated Formulation

• Toujeo (U-300 glargine) provides longer duration of action with lower hypoglycemia rates than U-100 glargine 4
• Requires approximately 10-18% higher daily doses compared to U-100 glargine 1