What is the typical starting dose and administration guidelines for glargine (insulin glargine) in patients requiring it?

Insulin Glargine (Lantus) Starting Dose and Administration

Starting Dose for Type 2 Diabetes

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

• The FDA-approved starting dose is 0.2 units/kg or up to 10 units once daily for patients not currently on insulin 2
• For a typical 50-70 kg patient, this translates to 10 units as the standard starting dose 1
• Patients with more severe hyperglycemia (A1C ≥9% or blood glucose ≥300-350 mg/dL) require higher starting doses of 0.3-0.4 units/kg/day 1
• Continue metformin unless contraindicated, and possibly one additional non-insulin agent when initiating basal insulin 1

Starting Dose for Type 1 Diabetes

For type 1 diabetes, start with approximately one-third of the total daily insulin requirement as glargine, with the remainder provided as rapid-acting insulin at meals. 2

• Total daily insulin requirements typically range from 0.4-1.0 units/kg/day, with 0.5 units/kg/day being typical for metabolically stable patients 1, 3
• Approximately 40-60% should be given as basal insulin (glargine) and 50-60% as prandial insulin 1, 3
• Glargine must be used concomitantly with short-acting insulin in type 1 diabetes 2

Administration Guidelines

Administer 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 and localized cutaneous amyloidosis 2
• Do not dilute or mix glargine with any other insulin or solution due to its low pH 1, 2
• Do not administer intravenously or via an insulin pump 2
• Visually inspect for particulate matter; use only if clear and colorless 2

Dose Titration Protocol

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

• 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, reduce the dose by 10-20% immediately 1
• Daily self-monitoring of fasting blood glucose is essential during titration 1

Special Populations Requiring Lower Doses

High-risk patients require reduced starting doses of 0.1-0.25 units/kg/day. 1

• Elderly patients (>65 years) 1
• Patients with renal failure (eGFR <60 mL/min/1.73 m²) 1
• Patients with poor oral intake 1
• Patients with retinopathy may require starting doses as low as 0.12 units/kg/day 1

Hospitalized Patients

For hospitalized patients who are insulin-naive or on low-dose insulin, start with a total daily dose of 0.3-0.5 units/kg, with half as basal insulin. 1

• For patients on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% to prevent hypoglycemia 1
• Lower doses (0.1-0.25 units/kg/day) are recommended for high-risk hospitalized patients 1

Critical Threshold: When to Add Prandial 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, 3

• Clinical signs of "overbasalization" include bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability 1
• Start prandial insulin with 4 units before the largest meal or 10% of the basal dose 1
• Continuing to escalate basal insulin beyond this threshold leads to suboptimal control and increased hypoglycemia risk 1

Switching from Other Insulins

Dose adjustments are required when switching to glargine to reduce hypoglycemia risk. 2

• From once-daily NPH: use the same dose 2
• From twice-daily NPH: use 80% of the total NPH dose 2
• From Toujeo (U-300 glargine): use 80% of the Toujeo dose 2
• Increase frequency of blood glucose monitoring during the transition 2

Common Pitfalls to Avoid

• Never delay insulin initiation in patients not achieving glycemic goals with oral medications 1
• Never rely solely on sliding scale insulin without optimizing basal insulin first—this approach is strongly discouraged and ineffective 1, 4
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia 1
• Never share insulin pens between patients, even if the needle is changed, due to risk of blood-borne pathogen transmission 2
• Never inject into areas of lipodystrophy or localized cutaneous amyloidosis, as this can result in hyperglycemia 2