Insulin Glargine (Lantus) Dosing Guidelines
For adults with type 2 diabetes who are insulin-naïve, start Lantus at 10 units once daily or 0.1–0.2 units/kg body weight, administered at the same time each day, while continuing metformin unless contraindicated. 1, 2
Initial Dosing Strategy
Standard Starting Dose
- Begin with 10 units once daily for most insulin-naïve adults with type 2 diabetes, or use 0.1–0.2 units/kg/day as an alternative weight-based approach. 1, 2
- Administer at the same time every day—morning, evening, or bedtime—based on patient preference, but consistency is essential. 1, 2
- Continue metformin at the maximum tolerated dose (up to 2,000–2,550 mg daily) when initiating Lantus, as this combination reduces total insulin requirements by 20–30% and yields superior glycemic control. 1
Higher Starting Doses for Severe Hyperglycemia
- For patients with HbA1c ≥9% or fasting glucose ≥300–350 mg/dL, consider starting at 0.3–0.4 units/kg/day to achieve more rapid control. 1
- In these cases, a basal-bolus regimen (combining Lantus with rapid-acting mealtime insulin) may be initiated immediately rather than basal insulin alone. 1
Lower Starting Doses for High-Risk Patients
- Elderly patients (>65 years), those with renal impairment (eGFR <60 mL/min/1.73 m²), or patients with poor oral intake should start at 0.1–0.25 units/kg/day to minimize hypoglycemia risk. 1
- For hospitalized patients on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% upon admission to prevent inpatient hypoglycemia. 1
Systematic Titration Protocol
Standard Titration Algorithm
- If fasting glucose is 140–179 mg/dL: increase Lantus by 2 units every 3 days. 1, 3
- If fasting glucose is ≥180 mg/dL: increase Lantus by 4 units every 3 days. 1, 3
- Target fasting glucose: 80–130 mg/dL (4.4–7.2 mmol/L). 1, 3
- If unexplained hypoglycemia occurs (glucose <70 mg/dL): immediately reduce the current dose by 10–20% before the next administration. 1, 3
Patient Self-Titration
- Equip patients with a self-titration algorithm based on daily fasting glucose measurements, empowering them to adjust doses every 3 days according to the standard rules above. 1
- Patients should measure fasting glucose each morning and record values to guide dose changes. 3
- Instruct patients to contact their healthcare provider if fasting glucose remains >180 mg/dL after 2–3 weeks of titration, or if the dose exceeds 0.5 units/kg/day without achieving target. 3
Critical Threshold: Recognizing Over-Basalization
When to Stop Escalating Basal Insulin
- Cease further Lantus increases once the dose reaches 0.5–1.0 units/kg/day without achieving glycemic targets; at this point, add prandial (mealtime) insulin or a GLP-1 receptor agonist instead. 1, 3
- Continuing to escalate basal insulin beyond this threshold leads to "over-basalization," which increases hypoglycemia risk without improving overall control. 1, 3
Clinical Signals of Over-Basalization
- Basal dose >0.5 units/kg/day with unmet HbA1c goals. 1, 3
- Bedtime-to-morning glucose differential ≥50 mg/dL, indicating excessive overnight basal insulin. 1, 3
- Recurrent hypoglycemia despite overall hyperglycemia. 1, 3
- Marked day-to-day glucose variability. 1, 3
Adding Prandial Insulin
- Start with 4 units of rapid-acting insulin (lispro, aspart, or glulisine) before the largest meal, or use 10% of the current basal dose as the initial prandial amount. 1
- Administer prandial insulin 0–15 minutes before meals for optimal postprandial control. 1
- Titrate each meal dose by 1–2 units (≈10–15%) every 3 days based on 2-hour postprandial glucose readings, targeting <180 mg/dL. 1
Monitoring Requirements
During Active Titration
- Daily fasting glucose checks are essential to guide basal insulin adjustments. 1, 3
- Reassess the dose every 3 days while titrating. 1, 3
- HbA1c measurement every 3 months during intensive titration phases. 1
After Stabilization
- Reassess every 3–6 months once the regimen is stable to review overall glycemic control and HbA1c. 3
- If HbA1c remains above target after 3–6 months despite achieving fasting glucose goals, consider adding prandial insulin. 1, 3
Administration Guidelines
Injection Technique
- Administer Lantus subcutaneously into the abdominal area, thigh, or deltoid. 2
- Rotate injection sites within the same region from one injection to the next to reduce the risk of lipodystrophy and localized cutaneous amyloidosis. 2
- Do not inject into areas of lipodystrophy or localized cutaneous amyloidosis, as this can result in hyperglycemia; a sudden change to an unaffected area may cause hypoglycemia. 2
Important Restrictions
- Do not administer intravenously or via an insulin pump. 2
- Do not dilute or mix Lantus with any other insulin or solution, as its low pH (4.0) makes it incompatible with other insulins. 2, 4, 5
- Visually inspect vials and pens for particulate matter and discoloration prior to administration; only use if the solution is clear and colorless with no visible particles. 2
Combination Therapy Considerations
Metformin Continuation
- Maintain metformin at the maximum tolerated dose (up to 2,000–2,550 mg daily) while titrating Lantus, unless contraindicated. 1, 3
- The combination of metformin and basal insulin typically reduces insulin requirements by 20–30% and provides superior control compared to insulin alone. 1
GLP-1 Receptor Agonist Option
- When basal insulin exceeds 0.5 units/kg/day and HbA1c remains above target, consider adding a GLP-1 receptor agonist (e.g., semaglutide) instead of prandial insulin. 1
- This approach offers comparable postprandial control with less hypoglycemia and weight loss rather than weight gain. 1
Hypoglycemia Management
Immediate Treatment
- Treat any glucose <70 mg/dL immediately with 15 g of fast-acting carbohydrate (e.g., 4 glucose tablets or 4 oz juice). 1
- Recheck glucose in 15 minutes and repeat treatment if needed. 1
Dose Adjustment
- If hypoglycemia occurs without an obvious cause, reduce the implicated insulin dose by 10–20% before the next administration. 1, 3
- Do not delay dose reduction after a hypoglycemic event; studies show 75% of hospitalized patients with hypoglycemia receive no basal insulin adjustment before the next dose. 1
Common Pitfalls to Avoid
Therapeutic Inertia
- Do not delay insulin initiation in patients who fail to meet glycemic goals with oral agents alone, as prolonged hyperglycemia increases complication risk. 1, 3
- Do not continue escalating Lantus beyond 0.5–1.0 units/kg/day without addressing postprandial hyperglycemia, as this leads to over-basalization and higher hypoglycemia risk. 1, 3
Medication Management
- Do not discontinue metformin when initiating or increasing Lantus unless contraindicated; the combination yields superior glycemic control and mitigates weight gain. 1, 3
- Avoid using sliding-scale insulin as monotherapy while titrating basal insulin; major diabetes guidelines condemn this practice because it causes erratic glucose fluctuations. 1, 3
Administration Errors
- Never fully discontinue basal insulin in type 1 diabetes or insulin-dependent type 2 diabetes, even when patients are NPO, to prevent diabetic ketoacidosis. 1
- Do not give rapid-acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk. 1
Expected Clinical Outcomes
Glycemic Control
- With appropriate basal insulin titration, approximately 68% of patients achieve mean glucose <140 mg/dL, compared with 38% when dosing is inadequate. 1
- Basal insulin optimization alone can produce an HbA1c reduction of 1.5–2.0%. 1
- Adding prandial insulin can yield an additional 2–3% HbA1c reduction. 1
Safety Profile
- Properly implemented regimens do not increase hypoglycemia risk relative to under-dosed insulin. 1
- The principal advantage of Lantus over NPH insulin is a lower frequency of hypoglycemic reactions, especially nocturnal hypoglycemia, affording improved safety. 4, 5
Special Populations
Type 1 Diabetes
- In type 1 diabetes, the recommended starting dose is approximately one-third of the total daily insulin requirements (≈0.5 units/kg/day for metabolically stable patients). 1, 2
- Lantus must be used concomitantly with short-acting, premeal insulin to satisfy the remainder of daily insulin requirements. 2
- Total daily insulin requirements typically range from 0.4–1.0 units/kg/day, with approximately 40–50% as basal insulin and 50–60% as prandial insulin. 1
Renal Impairment
- For patients with CKD stage 5, reduce total daily insulin by 50% for type 2 diabetes and by 35–40% for type 1 diabetes. 1
- Titrate conservatively in patients with eGFR <45 mL/min/1.73 m² to avoid hypoglycemia. 1