What is a reasonable starting dose of Lantus (insulin glargine) for a patient with severely elevated hemoglobin A1C (HbA1C) levels?

Starting Lantus in Patients with A1C >14%

For a patient with severely elevated A1C >14%, start with a basal-bolus insulin regimen immediately rather than basal insulin alone, using approximately 0.4-0.5 units/kg/day total daily dose, with 50% as Lantus (basal) and 50% as rapid-acting insulin (prandial) divided among meals. 1, 2

Why Basal-Bolus from the Start

• Patients with A1C ≥10-12% and/or blood glucose ≥300-350 mg/dL, especially if symptomatic or showing catabolic features, require basal-bolus insulin immediately as the preferred initial regimen. 1, 2
• An A1C >14% indicates profound hyperglycemia that cannot be adequately controlled with basal insulin alone—attempting basal-only therapy will unnecessarily prolong exposure to severe hyperglycemia and increase complication risk. 2, 3
• At this level of hyperglycemia, both fasting glucose (reflecting inadequate basal coverage) and postprandial glucose (requiring mealtime insulin) are severely elevated. 2, 3

Specific Dosing Algorithm

Initial Total Daily Dose Calculation

• Calculate 0.4-0.5 units/kg/day as the total daily insulin dose for severe hyperglycemia. 2, 4
• For a 70 kg patient, this equals 28-35 units total daily dose. 2

Basal Insulin (Lantus) Component

• Give 50% of total daily dose as Lantus once daily at the same time each day. 2, 4
• Using the example above: 14-18 units of Lantus once daily. 2
• Administer subcutaneously into the abdominal area, thigh, or deltoid, rotating injection sites. 4

Prandial Insulin Component

• Give the remaining 50% of total daily dose as rapid-acting insulin (lispro, aspart, or glulisine) divided among three meals. 2, 4
• Using the example above: approximately 5-6 units before each meal. 2
• Administer rapid-acting insulin 0-15 minutes before meals. 2

Aggressive Titration Protocol

Basal Insulin Titration

• Increase Lantus by 4 units every 3 days if fasting glucose ≥180 mg/dL. 2, 5
• Increase Lantus by 2 units every 3 days if fasting glucose is 140-179 mg/dL. 2, 5
• Target fasting plasma glucose: 80-130 mg/dL. 2, 5
• If hypoglycemia occurs, reduce the dose by 10-20% immediately. 2, 4

Prandial Insulin Titration

• Increase prandial insulin by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings. 2, 3
• Titrate each meal's insulin dose independently based on the postprandial glucose after that specific meal. 2, 3

Critical Threshold to Recognize

• When basal insulin exceeds 0.5 units/kg/day, focus on intensifying prandial insulin rather than continuing to escalate basal insulin alone. 2, 3
• Clinical signs of "overbasalization" include: basal dose >0.5 units/kg/day, bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability. 2

Foundation Therapy

• Continue metformin unless contraindicated, even when initiating intensive insulin therapy. 2, 3
• Metformin provides complementary glucose-lowering effects and reduces total insulin requirements. 2, 3
• Discontinue sulfonylureas when starting complex insulin regimens to reduce hypoglycemia risk. 1, 3

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during titration. 2, 5
• Monitor pre-meal and 2-hour postprandial glucose to guide prandial insulin adjustments. 2, 3
• Check A1C every 3 months during intensive titration. 2
• Assess for hypoglycemia at every clinical visit and adjust doses immediately if it occurs. 2, 4

Common Pitfalls to Avoid

• Do not start with basal insulin alone at this A1C level—this approach will fail to address postprandial hyperglycemia and unnecessarily prolong severe hyperglycemia. 1, 2
• Do not rely on sliding scale insulin without a scheduled basal-bolus regimen—sliding scale alone is strongly discouraged and ineffective for glycemic management. 2, 3
• Do not delay insulin intensification while trying additional oral agents—at A1C >14%, non-insulin agents alone cannot achieve adequate control. 2, 3
• Do not continue escalating basal insulin beyond 0.5-1.0 units/kg/day without addressing postprandial hyperglycemia—this leads to overbasalization with increased hypoglycemia risk and suboptimal control. 2, 3

Patient Education Essentials

• Teach proper insulin injection technique and site rotation. 3, 4
• Provide education on self-monitoring of blood glucose. 2, 3
• Ensure patients can recognize and treat hypoglycemia. 2, 3
• Supply written instructions for insulin dose adjustments based on glucose patterns. 3
• Educate on "sick day" management rules. 3

Alternative Consideration

• Consider adding a GLP-1 receptor agonist to the insulin regimen to improve A1C while minimizing weight gain and hypoglycemia risk, though this is adjunctive to—not a replacement for—intensive insulin therapy at this A1C level. 2, 3