What is the recommended dosing regimen for Lantus (glargine) in a patient with diabetes mellitus requiring insulin therapy?

Lantus (Insulin Glargine) Dosing Guidelines

Starting Dose for Type 2 Diabetes

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

• Continue metformin (unless contraindicated) and possibly one additional non-insulin agent when initiating Lantus 1
• For patients with severe hyperglycemia (A1C ≥9%, blood glucose ≥300-350 mg/dL, or symptomatic/catabolic features), consider higher starting doses of 0.3-0.5 units/kg/day as total daily insulin using a basal-bolus regimen from the outset 1

Starting Dose for Type 1 Diabetes

For type 1 diabetes, start with approximately one-third of the total daily insulin requirement as Lantus, with the remainder provided as short-acting premeal insulin. 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
• Approximately 40-60% should be basal insulin (Lantus) and 40-60% as prandial insulin 1

Dose Titration Algorithm

Increase Lantus by 2 units every 3 days if fasting glucose is 140-179 mg/dL, or by 4 units every 3 days if fasting glucose is ≥180 mg/dL, until fasting plasma glucose reaches 80-130 mg/dL. 1

• If hypoglycemia occurs without clear cause, reduce the dose by 10-20% immediately 1
• Daily fasting blood glucose monitoring is essential during titration 1
• If more than 2 fasting glucose values per week are <80 mg/dL, decrease the dose by 2 units 1

Critical Threshold: When to Stop Escalating Basal Insulin

When Lantus exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin or a GLP-1 receptor agonist rather than continuing to escalate basal insulin alone. 1

Signs of Overbasalization:

• Basal dose >0.5 units/kg/day 1
• Bedtime-to-morning glucose differential ≥50 mg/dL 1
• Hypoglycemia episodes 1
• High glucose variability 1

Adding Prandial Insulin

Start with 4 units of rapid-acting insulin before the largest meal OR use 10% of the current basal dose. 1

• Titrate prandial insulin by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 1
• Add prandial insulin when basal insulin has been optimized (fasting glucose 80-130 mg/dL) but A1C remains above target after 3-6 months 1

Administration Guidelines

Administer Lantus subcutaneously once daily at any time of day but at the same time every day. 2

• Inject into the abdominal area, thigh, or deltoid, rotating injection sites within the same region 2
• Do not administer intravenously or via an insulin pump 2
• Do not dilute or mix Lantus with any other insulin or solution due to its low pH 1, 2

Switching from Other Insulins

When switching from twice-daily NPH insulin to once-daily Lantus, start with 80% of the total NPH dosage. 2

• When switching from once-daily NPH to once-daily Lantus, use the same dosage 2
• When switching from Toujeo (U-300 glargine) to Lantus (U-100 glargine), start with 80% of the Toujeo dosage 2

Special Populations

Hospitalized Patients:

• For insulin-naive or low-dose insulin patients: start with 0.3-0.5 units/kg/day total daily dose, with half as basal insulin 1
• For patients on high-dose home insulin (≥0.6 units/kg/day): reduce total daily dose by 20% to prevent hypoglycemia 1
• For high-risk patients (elderly >65 years, renal failure, poor oral intake): use lower doses of 0.1-0.25 units/kg/day 1

Renal Impairment:

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

Common Pitfalls to Avoid

Never delay insulin initiation in patients not achieving glycemic goals with oral medications—this prolongs hyperglycemia exposure and increases complication risk. 1

• Never discontinue metformin when starting insulin unless contraindicated—this leads to higher insulin requirements and more weight gain 1
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this causes overbasalization with increased hypoglycemia risk 1
• Never use sliding scale insulin as monotherapy—it treats hyperglycemia reactively rather than preventing it 1

Pharmacological Advantages

Lantus provides a peakless, 24-hour insulin profile with significantly lower rates of nocturnal hypoglycemia compared to NPH insulin. 3, 4, 5

• The risk of severe hypoglycemia is reduced by 46% and severe nocturnal hypoglycemia by 59% compared to NPH insulin 3
• Lantus has a slower onset and longer duration of action than NPH insulin, resulting in more stable glycemic control 4, 6