What is the recommended initial dose and regimen for insulin glargine in a patient with diabetes requiring insulin therapy?

Insulin Glargine (Lantus) Initial Dosing and Regimen

Recommended Starting Dose

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 once daily, administered at the same time each day. 1, 2 For patients with type 1 diabetes, the recommended starting dose is approximately one-third of total daily insulin requirements, with short-acting premeal insulin providing the remainder. 1, 2

Type 2 Diabetes: Standard Initiation

• Start with 10 units once daily or 0.1-0.2 units/kg/day for patients with mild-to-moderate hyperglycemia (HbA1c <9%). 1
• Administer at the same time every day (bedtime, morning, or any consistent time). 1, 2
• Continue metformin unless contraindicated, and possibly one additional non-insulin agent. 1
• The FDA label confirms administration should be subcutaneous once daily at any time but at the same time every day. 2

Type 2 Diabetes: Severe Hyperglycemia

• For patients with HbA1c ≥9%, blood glucose ≥300-350 mg/dL, or HbA1c 10-12% with 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
• These patients require both basal and prandial coverage immediately, not basal insulin alone. 1

Type 1 Diabetes: Basal-Bolus Regimen Required

• Total daily insulin requirement: 0.4-1.0 units/kg/day, with 0.5 units/kg/day typical for metabolically stable patients. 1
• Divide as 40-60% basal insulin (glargine) and 50-60% prandial insulin (rapid-acting analog) split among meals. 1, 3
• The FDA label explicitly states that in type 1 diabetes, insulin glargine must be used concomitantly with short-acting insulin. 2
• Higher doses are required immediately following ketoacidosis presentation. 1

Dose Titration Algorithm

• Increase by 2 units every 3 days if fasting glucose is 140-179 mg/dL. 1
• Increase by 4 units every 3 days if fasting glucose is ≥180 mg/dL. 1
• Target fasting plasma glucose: 80-130 mg/dL. 1
• If hypoglycemia occurs without clear cause, reduce dose by 10-20% immediately. 1
• Equip patients with self-titration algorithms based on daily fasting glucose monitoring. 1

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 a GLP-1 receptor agonist rather than continuing to escalate basal insulin alone. 1, 3 Clinical signals of "overbasalization" include:

• 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 (When Needed)

• 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 if after 3-6 months of basal optimization, fasting glucose reaches target but HbA1c remains above goal. 1

Administration Guidelines

• Administer subcutaneously 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 FDA label explicitly prohibits dilution or mixing with any other insulin or solution. 2
• Visually inspect for particulate matter; use only if clear and colorless. 2

Special Populations Requiring Dose Adjustment

• Hospitalized patients on high-dose home insulin (≥0.6 units/kg/day): Reduce total daily dose by 20% upon admission. 1
• High-risk patients (elderly >65 years, renal failure, poor oral intake): Use lower doses of 0.1-0.25 units/kg/day. 1
• Patients on enteral/parenteral feeding: Start with 10 units of insulin glargine every 24 hours. 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 is explicitly condemned by all major diabetes guidelines and shown to be ineffective. 1

Monitoring Requirements

• Daily fasting blood glucose monitoring is essential during the titration phase. 1
• Assess adequacy of insulin dose at every clinical visit. 1
• Recheck HbA1c every 3 months during active titration, then every 6 months once stable. 1
• During any insulin regimen changes, increase frequency of blood glucose monitoring. 2